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Amylolytic bacterial lactic acid fermentation - A review
Abstract
Lactic acid, an enigmatic chemical has wide applications in food, pharmaceutical, leather, textile industries and as chemical feed stock. Novel applications in synthesis of biodegradable plastics have increased the demand for lactic acid. Microbial fermentations are preferred over chemical synthesis of lactic acid due to various factors. Refined sugars, though costly, are the choice substrates for lactic acid production using Lactobacillus sps. Complex natural starchy raw materials used for production of lactic acid involve pretreatment by gelatinization and liquefaction followed by enzymatic saccharification to glucose and subsequent conversion of glucose to lactic acid by Lactobacillus fermentation. Direct conversion of starchy biomass to lactic acid by bacteria possessing both amylolytic and lactic acid producing character will eliminate the two step process to make it economical. Very few amylolytic lactic acid bacteria with high potential to produce lactic acid at high substrate concentrations are reported till date. In this view, a search has been made for various amylolytic LAB involved in production of lactic acid and utilization of cheaply available renewable agricultural starchy biomass. Lactobacillus amylophilus GV6 is an efficient and widely studied amylolytic lactic acid producing bacteria capable of utilizing inexpensive carbon and nitrogen substrates with high lactic acid production efficiency. This is the first review on amylolytic bacterial lactic acid fermentations till date.
... References Food Additive L-lactic acid BPF [1,8,9] Flavor enhancer (acidulant) L-lactic acid BPF [8][9][10] Preserver L-lactic acid BPF [8,11,12] Texturizer L-lactic acid BPF [8,12,13] Bacterial inhibitor L-lactic acid BPF [5,8,14] Cosmetics Texturizer (rejuvenation) L-lactic acid or racemic mixture (DL) 0.4-0.9% [10,12] Skin lightener L-lactic acid or racemic mixture (DL) 0.4-0.9% ...
... References Food Additive L-lactic acid BPF [1,8,9] Flavor enhancer (acidulant) L-lactic acid BPF [8][9][10] Preserver L-lactic acid BPF [8,11,12] Texturizer L-lactic acid BPF [8,12,13] Bacterial inhibitor L-lactic acid BPF [5,8,14] Cosmetics Texturizer (rejuvenation) L-lactic acid or racemic mixture (DL) 0.4-0.9% [10,12] Skin lightener L-lactic acid or racemic mixture (DL) 0.4-0.9% ...
... References Food Additive L-lactic acid BPF [1,8,9] Flavor enhancer (acidulant) L-lactic acid BPF [8][9][10] Preserver L-lactic acid BPF [8,11,12] Texturizer L-lactic acid BPF [8,12,13] Bacterial inhibitor L-lactic acid BPF [5,8,14] Cosmetics Texturizer (rejuvenation) L-lactic acid or racemic mixture (DL) 0.4-0.9% [10,12] Skin lightener L-lactic acid or racemic mixture (DL) 0.4-0.9% [9,15] Humectant L-lactic acid or racemic mixture (DL) 0.4-0.9% ...
Lactic acid is a vital organic acid with a wide range of industrial applications, particularly in the food, pharmaceutical, cosmetic, and biomedical sectors. The conventional production of lactic acid from refined sugars poses high costs and significant environmental impacts, leading to the exploration of alternative raw materials and more sustainable processes. Lignocellulosic biomass, particularly agro-industrial residues such as agave bagasse, represents a promising substrate for lactic acid production. Agave bagasse, a by-product of the tequila and mezcal industries, is rich in fermentable carbohydrates, making it an ideal raw material for biotechnological processes. The use of lactic acid bacteria (LAB), particularly genetically modified microorganisms (GMMs), has been shown to enhance fermentation efficiency and lactic acid yield. This review explores the potential of lignocellulosic biomass as a substrate for microbial fermentation to produce lactic acid and other high-value products. It covers the composition and pretreatment of some agricultural residues, the selection of suitable microorganisms, and the optimization of fermentation conditions. The paper highlights the promising future of agro-industrial residue valorization through biotechnological processes and the sustainable production of lactic acid as an alternative to conventional methods.
... rhamnosus (RBL 45), which have been found to possess high xylanase activity, also possess high α-amylase activity, which may suggest optimal glycosyl hydrolase activity. The amylolytic capacity of Lb. plantarum is invariably reported [59][60][61][62]. Furthermore, [59] suggested strains from Lc. lactis species to be amylolytic as well. ...
... A good mixture of protease, peptidase, and amylase activities, in addition to β-glucosidase and phytase activities, have been recorded in strains of Lb. plantarum, Lb. fermentum, Lb. curvatus, Leuc. mesenteroides, and P. pentosaceus isolated from sourdough [62,80,83,[87][88][89]. ...
Twenty-eight strains of lactic acid bacteria (LAB) were characterized for the ability to express enzymes of interest (including protease, xylanase, α-amylase, laccase, and glucose oxidase) as well as the ability to produce exopolysaccharide (EPS). The screening of enzyme capability for all LAB strains proceeded in a progressive 3-stage manner that helps to profile the efficiency of LAB strains in expressing chosen enzymes (Stage 1), highlights the strains with affinity for flour as the substrate (Stage 2), and discerns strains that can adapt well in a simulated starter environment (Stage 3). The theoretical ability of LAB to express these enzymes was also assessed using Basic Local Alignment Search Tool (BLAST) analysis to identify the underlying genes in the whole genome sequence. By consolidating both experimental data and information obtained from BLAST, three LAB strains were deemed optimal in expressing enzymes, namely, Lb. delbrueckii subsp. bulgaricus (RBL 52), Lb. rhamnosus (RBL 102), and Lb. plantarum (ATCC 10241). Meanwhile, EPS-producing capabilities were observed for 10 out of 28 LAB strains, among which, Lactococcus lactis subsp. diacetylactis (RBL 37) had the highest total EPS yield (274.15 mg polysaccharide/L culture) and produced 46.2% polysaccharide with a molecular mass of more than 100 kDa.
... (Dida et al. 2018). Our result showed a slightly lower pH in the rinse water (pH = 3.71), possibly due to the LAB using the added glucose to produce lactic acid and hydrolysing the sprout seed carbohydrates (Reddy et al. 2008). A pH lower than 4.5 is known to limit the growth of most food-borne pathogens (Rahman 2007). ...
... A pH lower than 4.5 is known to limit the growth of most food-borne pathogens (Rahman 2007). Moreover, increased lactic, acetic acid, and total organic acid during sprouting indicate LAB fermentation of exogenous glucose and amylolytic starch (Reddy et al. 2008;Nkhata et al. 2018). Some studies of LAB or organic acids (lactic acid, acetic acid) as seed treatments during sprouting have had positive effects with implications for sprouting (Lang et al. 2000;Ding et al. 2013;Sikin et al. 2013;Budryn et al. 2019;Rossi and Lathrop 2019). ...
Sprouting has been used widely to enrich the nutritional quality of cereals and legumes. It improves the bioavailability of nutrients, especially those bound to phytic acid. However, sprouting is a good medium for microbial growth; thus, producing safe sprouts from harmful microbial growth is challenging. In food biotechnology, lactic acid bacteria (LAB) can be potentially used to improve nutrition and play a vital role as competitive microbes in food preservation. Therefore, supporting natural LAB growth by adding glucose sources during sprouting can produce a safer sprouting medium. Chickpeas (Cicer arietinum L.) sprouted for up to 50 h with glucose (0.1% and 1%) under aero-anaerobic conditions, with recycled water periodically spraying on the sprouts to support the natural LAB growth. Results show increased LAB counts, lactic acid and acetic acid, and decreased pH. Moreover, the addition of glucose had no significant detrimental effects on sprout quality compared to the control sample relative to nutritional compounds, such as saccharides, which remained similar. This sprouting method can be scaled up to production levels and is considerably cheaper than other treatments.
... The Lactobacillus species, which belong to the category of LAB, have a notable impact on the fermentation process and demonstrate diverse mechanisms that promote health. The microorganisms possess the capacity to transform carbohydrates into lactic acid via the process of fermentation [35]. The process of fermentation not only imparts the distinctive tart taste and consistency to fermented foods and beverages but also leads to the synthesis of antimicrobial compounds such as organic acids [36], exopolysaccharides [37], and bacteriocins [38]. ...
... Lactic acid bacteria (LAB) have the capability of efficient protein and monosaccharide degradation, [16] such as Limosilactobacillus. [17] Its whole genome annotation has confirmed its potential to hydrolyze macromolecular organic matter. [18] This LAB can achieve hydrolysis of polysaccharides, lipids, and proteins by secreting enzymes such as glycosyltransferases, [19] esterases [20] , and proteases. ...
The efficient co‐production of H2 and CH4 via anaerobic digestion (AD) requires separate stages, as it cannot yet be achieved in one step. Lactic acid bacteria (LAB) (Limosilactobacillus) release H2 and acetate by enhancing hydrolysis, potentially increasing CH4 production with simultaneous H2 accumulation. This study investigated the enhanced effect of one‐step co‐production of H2 and CH4 in AD by LAB and elucidated its enhancement mechanisms. The results showed that 236.3 times increase in H2 production and 7.1 times increase in CH4 production are achieved, resulting in profits of 469.39 USD. Model substrates lignocellulosic straw, sodium acetate, and H2 confirmes LAB work on the hydrolysis stage and subsequent sustainable volatile fatty acid production during the first 6 days of AD. In this stage, the enrichment of Limosilactobacillus carrying bglB and xynB, the glycolysis pathway, and the high activity of protease, acetate kinase, and [FeFe] hydrogenase, jointly achieved rapid acetate and H2 accumulation, driving hydrogenotrophic methanogenesis dominated. From day 7 to 24, with enriched Methanosarcina, and increased methenyltetrahydromethanopterin hydrogenase activity, continuously produced acetate led to the mainly acetoclastic methanogenesis shift from hydrogenotrophic methanogenesis. The power generation capacity of LAB‐enhanced AD is 333.33 times that of China's 24,000 m³ biogas plant.
... Lactic acid fermentation: Since its possible uses in a variety of industries, particularly in food and the production of biodegradable plastics, lactic acid fermentation has drawn a lot of attention (Reddy et al., 2008). This type, which is carried out by lactic acid bacteria (LAB), creates foods like kimchi, sauerkraut, and yoghurt (Park and Kim, 2019). ...
... Lactic acid bacteria are gram-positive bacteria in the form of cocci, non-sporing rods and are microaerophilic. These organisms are heterotrophic and generally require complex nutrition during their growth and development [17]. Lactic acid bacteria are commonly used as probiotics because they are non-pathogenic and nontoxigenic. ...
Consuming fermented foods to increase microbial diversity and high-fiber foods will provide more significant synergistic benefits. The purpose of this study was to analyze the chemical quality of corn tape with different fermentation times. This research was an experimental study using a completely randomized design. The treatment in this study was the length of fermentation in making corn tape, including five days, six days, and seven days. The analysis results showed significant differences in the protein content, lactic acid bacteria, pH, antioxidant capacity, and flavonoid content of fermented corn tape at different times. The longer the fermentation, the higher the protein content, lactic acid bacteria content, and flavonoid content, the stronger the antioxidant capacity and the more acidic the pH of corn tape. The conclusion is that the fermentation duration can affect corn tape's chemical quality.
... Hence, the two strains D12 and D7 were able to reduce the pH to below 4 after 8 h of incubation as compared to other strains. Detection of amylase activity in LAB has been demonstrated by several researchers [20,21]. The amylase enzyme in LAB has been reported to play a direct role on starch molecules by converting starch into simpler monomers which aid liquification of starch-based products [22]. ...
This study aimed to explore the fermentative performance of nine lactic acid bacterial strains with probiotic potential during sorghum fermentation. The strain’s attributes including proliferation counts, pH levels, production of organic acid antibacterial activity, and their ability to break down starch were evaluated during the fermentation period in the presence and absence of glucose as a carbon source. In addition, the inhibitory activity of these potential probiotic strains against pathogenic bacteria (Salmonella typhimurium, Escherichia coli, and Staphylococcus aureus) was examined through a co-culturing technique. The results demonstrated that all 4 Lactobacillus strains exhibited robust growth in both glucose and glucose-free fermentation experiments. Glucose supplementation significantly enhanced lactic acid yield which ranged from 0.19 to 0.44% compared to fermentation without glucose which ranged from 0.04 to 0.29%. The selected Lactobacillus strains effectively lowered the media pH below 4.0 after 24 h, producing substantial lactic acid. Notably, in the absence of glucose, only Lb. helveticus D7 and Lb. amylolyticus D12 achieved pH levels below 4 after 8 h, producing the highest lactic acid amounts of 0.27 and 0.29% after 24 h, respectively. Amylase activity was detected on two strains, D7 and D12. Furthermore, most of the tested Lactobacillus strains demonstrated complete inhibition (6 log to 0 Log CFU/mL) of pathogen growth after 24 h of co-culturing, suggesting their potential for enhancing the safety quality of sorghum-based fermented products.
... Hence, the two strains D12 and D7 were able to reduce the pH to below 4 after 8 hours of incubation as compared to other strains. Detection of amylase activity in LAB has been demonstrated by several researchers ( [20,21]. The amylase enzyme in LAB has been reported to play a direct role on starch molecules by converting starch into simpler monomers which aid liquification of starch-based products [22]. ...
This study aimed to explore the fermentation behavior of selected potential probiotic strains during sorghum fermentation, considering their microbial counts, pH levels, and antibacterial activity, their ability to break down starch. The fermentation processes were conducted in the presence and absence of glucose, and the lactic acid bacterial strains underwent controlled fermentation to assess microbial counts, amylase activity, pH, and lactic acid levels in the presence and absence of glucose. In addition, the inhibitory activity of these potential probiotic strains against pathogenic bacteria (Salmonella typhimurium, Escherichia coli, and Staph-ylococcus aureus) was examined through co-culturing. The results demonstrated that all nine Lactobacillus strains exhibited robust growth in both sugar and sugar-free fermentation experiments. Glucose supple-mentation significantly enhanced lactic acid yield which was in a range of 0.19-0.52 % compared to fer-mentation without glucose with a range of 0.03-0.29 %. The selected Lactobacillus strains effectively lowered the pH to less than 4 after 24 hours, producing substantial lactic acid. Notably, in the absence of glucose, only Lb. helveticus D7 and Lb. amylolyticus D12 achieved pH levels below 4 after 8 hours, producing the highest lactic acid amounts of 0.27 and 0.29 % after 24 hours, respectively. Amylase activity was detected on two strains D7 and D12. Furthermore, most of the tested Lactobacillus strains demonstrated complete inhibition of pathogen growth after 24 hours of co-culturing, suggesting their potential for enhancing the safety quality of sorghum-based fermented products.
... The first one involves the bio-fermentation of carbohydrates with microorganisms, which is complex and requires an extended fermentation period (typically 3-5 days). [7][8][9][10] The complex handling of pH sensitive microbes hinders the LA's purity and productivity. Therefore, effective processes for pH control and purification to improve the quality of LA are necessary. ...
Highly robust Zr-based MOF-808, featuring Lewis acid Zr sites and coordinate hydroxide ions upon the removal of monocarboxylate capping reagent, emerges as an efficient catalyst for the hydrothermal conversion of...
... Interestingly, along with the genes responsible for aerobic respiration, the strain's genome also includes genes encoding key enzyme such as lactate dehydrogenase" (LDH), which facilitates the conversion of pyruvate to lactate, enabling the regeneration of NAD + from NADH, an essential component to maintain glycolysis under no or low oxygen concentration. This process provides a direct means of producing energy in the absence of oxygen (Reddy et al., 2008). The presence of LDH gene demonstrates that the strain has the potential to perform lactate fermentation and grow anaerobically. ...
In this study we describe the first cultured representative of Candidatus Synoicihabitans genus, a novel strain designated as LMO-M01T, isolated from deep-sea sediment of South China Sea. This bacterium is a facultative aerobe, Gram-negative, non-motile, and has a globular-shaped morphology, with light greenish, small, and circular colonies. Analysis of the 16S rRNA gene sequences of strain LMO-M01T showed less than 93% similarity to its closest cultured members. Furthermore, employing advanced phylogenomic methods such as comparative genome analysis, average nucleotide identity (ANI), average amino acid's identity (AAI), and digital DNA-DNA hybridization (dDDH), placed this novel species within the candidatus genus Synoicihabitans of the family Opitutaceae, Phylum Verrucomicrobiota. The genomic analysis of strain LMO-M01T revealed 175 genes, encoding putative carbohydrate-active enzymes. This suggests its metabolic potential to degrade and utilize complex polysaccharides, indicating a significant role in carbon cycling and nutrient turnover in deep-sea sediment. In addition, the strain’s physiological capacity to utilize diverse biopolymers such as lignin, Xylan, starch, and agar as sole carbon source opens up possibilities for sustainable energy production and environmental remediation.
Moreover, the genome sequence of this newly isolated strain has been identified across diverse ecosystems, including marine sediment, fresh water, coral, soil, plants, and activated sludge highlighting its ecological significance and adaptability to various environments. The recovery of strain LMO-M01T holds promise for taxonomical, ecological and biotechnological applications. Based on the polyphasic data, we propose that this ecologically important strain LMO-M01T represents a novel genus (previously Candidatus) within the family.
Opitutaceae of phylum Verrucomicrobiota, for which the name Synoicihabitans lomoniglobus gen. nov., sp. nov. was
proposed. The type of strain is LMO-M01T (= CGMCC 1.61593T = KCTC 92913T).
... From the results, it was found that the rate constant (K) of lactic acid production for control is 3.20×10 -5 min -1 , US treatment before inoculation is 2.28×10 -4 min -1 and US treatment after inoculation is 3.15×10 -3 (Table 2). During fermentation, two major changes occur (i) lactic acid synthesis by LAB, and (ii) the formation of volatile compounds, which are important for flavor formation in the finished product (Reddy et al., 2008). L. rhamnosus is a facultatively heterofermentative bacteria, during fermentation which converts hexoses into L (+) lactic acid, according to the Embden-Meyerhof Pathway (EMP), and because of the presence of aldolase and phosphoketolase enzymes, it also ferments pentoses. ...
... * P < 0.05, ** P < 0.01, *** P < 0.001. n = 12 fish per group The effect of inulin (or non-digestible polysaccharides) is mainly mediated by the intestinal microbiome via the production of bacterial metabolites such as SCFA or lactate [49,50]. Moreover, a high CHO/protein ratio can affect the rainbow trout gut microbiota and in particular the Firmicutes/Proteobacteria ratio as well as the lacticacid bacteria [6]. ...
Background
High dietary carbohydrates can spare protein in rainbow trout ( Oncorhynchus mykiss ) but may affect growth and health. Inulin, a prebiotic, could have nutritional and metabolic effects, along with anti-inflammatory properties in teleosts, improving growth and welfare. We tested this hypothesis in rainbow trout by feeding them a 100% plant-based diet, which is a viable alternative to fishmeal and fish oil in aquaculture feeds. In a two-factor design, we examined the impact of inulin (2%) as well as the variation in the carbohydrates (CHO)/plant protein ratio on rainbow trout. We assessed the influence of these factors on zootechnical parameters, plasma metabolites, gut microbiota, production of short-chain fatty acids and lactic acid, as well as the expression of free-fatty acid receptor genes in the mid-intestine, intermediary liver metabolism, and immune markers in a 12-week feeding trial.
Results
The use of 2% inulin did not significantly change the fish intestinal microbiota, but interestingly, the high CHO/protein ratio group showed a change in intestinal microbiota and in particular the beta diversity, with 21 bacterial genera affected, including Ralstonia , Bacillus , and 11 lactic-acid producing bacteria. There were higher levels of butyric, and valeric acid in groups fed with high CHO/protein diet but not with inulin. The high CHO/protein group showed a decrease in the expression of pro-inflammatory cytokines ( il1b, il8 , and tnfa ) in liver and a lower expression of the genes coding for tight-junction proteins in mid-intestine ( tjp1a and tjp3 ). However, the 2% inulin did not modify the expression of plasma immune markers. Finally, inulin induced a negative effect on rainbow trout growth performance irrespective of the dietary carbohydrates.
Conclusions
With a 100% plant-based diet, inclusion of high levels of carbohydrates could be a promising way for fish nutrition in aquaculture through a protein sparing effect whereas the supplementation of 2% inulin does not appear to improve the use of CHO when combined with a 100% plant-based diet.
... The most abundant genus of lactic acid bacteria, Lactobacillus, includes approximately 80 species [51]. The preferred substrate for lactic acid production by bacteria is simple sugars [52]. LAF of grains, vegetables, and seafood is an important technology that has provided suppression of the growth of harmful microorganisms in foods in regions where adequate preservation facilities are not available [53]. ...
Fermentation of both microalgae and macroalgae is one of the most efficient methods of obtaining valuable value-added products due to the minimal environmental pollution and the availability of economic benefits, as algae do not require arable land and drift algae and algal bloom biomass are considered waste and must be recycled and their fermentation waste utilized. The compounds found in algae can be effectively used in the fuel, food, cosmetic, and pharmaceutical industries, depending on the type of fermentation used. Products such as methane and hydrogen can be produced by anaerobic digestion and dark fermentation of algae, and lactic acid and its polymers can be produced by lactic acid fermentation of algae. Article aims to provide an overview of the different types potential of micro- and macroalgae fermentation, the advantages and disadvantages of each type considered, and the economic feasibility of algal fermentation for the production of various value-added products.
... Certain LAB can produce amylolytic enzymes, e.g. amylases, which degrade starch to maltose and glucose (Reddy, Altaf, Naveena, Venkateshwar, & Kumar, 2008). LAB can then, indirectly, use starch as a carbon source for growth. ...
... 8,S3 and S6;Table S3). Besides, the photosynthesis process of Chroococcus sp. could produce carbon source for the growth of soil microbes, which consequently resulted in increased abundances of typical acid-producing bacteria in cyanobacteria-treated groups (Fig. 6a), such as Lactobacillus (Reddy et al. 2008), Tumebacillus (Kim and Kim 2016) and Chitinophaga (Han et al. 2014). The acid released by soil bacteria may facilitate the dissolution of metal phosphate (Padder et al. 2021;Jiang et al. 2022). ...
The possibility of using the non-nitrogen-fixing cyanobacterium (Chroococcus sp.) for the reduction of soil nitrate contamination was tested through Petri dish experiments. The application of 0.03, 0.05 and 0.08 mg/cm²Chroococcus sp. efficiently removed NO3⁻-N from the soil through assimilation of nitrate nutrient and promotion of soil denitrification. At the optimal application dose of 0.05 mg/cm², 44.06%, 36.89% and 36.17% of NO3⁻-N were removed at initial NO3⁻-N concentrations of 60, 90 and 120 mg/kg, respectively. The polysaccharides released by Chroococcus sp. acted as carbon sources for bacterial denitrification and facilitated the reduction of soil salinity, which significantly (p < 0.05) stimulated the growth of denitrifying bacteria (Hyphomicrobium denitrificans and Hyphomicrobium sp.) as well as significantly (p < 0.05) elevated the activities of nitrate reductase and nitrite reductase by 1.07–1.23 and 1.15–1.22 times, respectively. The application of Chroococcus sp. promoted the dominance of Nocardioides maradonensis in soil microbial community, which resulted in elevated phosphatase activity and increased available phosphorus content. The application of Chroococcus sp. positively regulated the growth of soil bacteria belonging to the genera Chitinophaga, Prevotella and Tumebacillus, which may contribute to increased soil fertility through the production of beneficial enzymes such as invertase, urease and catalase. To date, this is the first study verifying the remediation effect of non-nitrogen-fixing cyanobacteria on nitrate-contaminated soil.
... In this work, we present an eco-friendly flexible electret loudspeaker that utilizes polylactic acid (PLA) electret film, paper substrates, and carbon electrodes. PLA is a thermoplastic biopolymer that can be extracted from corn, potato starch, cassava root, or sugar cane 34 . It is biodegradable, biocompatible, and highly moldable, with excellent mechanical strength 35,36 . ...
Flexible loudspeakers that can be easily distributed in the surrounding environment are essential for creating immersive experiences in human-machine interactions, as these devices can transmit acoustic information conveniently. In this paper, we present a flexible electret loudspeaker that offers numerous benefits, such as eco-friendly, easy fabrication, flexible customization, strong durability, and excellent outputs. The output sound pressure level (SPL) and frequency response characteristic are optimized according to the simulation and experiment results. At a distance of 50 meters, a large-size loudspeaker (50 × 40 cm ² ) can produce an average SPL of 60 dB (normal SPL range of human voices is between 40 to 70 dB). The frequency response of our loudspeaker is high and relatively consistent up to 15 kHz, which covers the normal frequency range of human voices (<8 kHz). As demonstrated in this work, our loudspeakers can be used for scalable applications, such as being integrated with curtains or hung up like posters, offering a promising and practical solution for creating better human-machine interaction experiences.
... The Lactobacillus species, which belong to the category of LAB, have a notable impact on the fermentation process and demonstrate diverse mechanisms that promote health. The microorganisms possess the capacity to transform carbohydrates into lactic acid via the process of fermentation [35]. The process of fermentation not only imparts the distinctive tart taste and consistency to fermented foods and beverages but also leads to the synthesis of antimicrobial compounds such as organic acids [36], exopolysaccharides [37], and bacteriocins [38]. ...
Water kefir beverages have gained attention as a potential alternative to soda,
offering a non-alcoholic and naturally fermented option that can be enriched with
various fruits and vegetables to enhance both flavor and health benefits. Water
kefir exhibits variability in its characteristic all over the world which can be
attributed to several factors. In this book chapter, we explore the diverse range of
water kefir products available and highlight innovative approaches to enhance
their probiotic potential. Water kefir provides a multitude of health benefits,
including the presence of probiotics and juice components that supports antioxidant
activities, gut microbiota modulation, immunomodulation, enhanced nutrient
absorption, and improvement of metabolic activities. Exploring the utilization
of different substrates rich in bioactive compounds, including the valorization of
food waste, holds promise for the development of novel attributes and economic
value in water kefir beverages. Certain fruits and vegetables exhibit higher
microbial viability than others, emphasizing the importance of substrate selection
in water kefir fermentation. Consideration of the chemical composition of the
chosen fruits or vegetables is essential, as it not only stimulates the fermentation
process but also contributes to the development of flavors. The microbial composition
of water kefir beverages is primarily influenced by the grains used in the
fermentation process, which, in turn, is affected by their origin. Despite the
growing demand for healthy, refreshing, low-sugar, and ready-to-drink probiotic
beverages, there remains a limited exploration of water kefir fermentation using
diverse substrates and its large-scale production. To fully capitalize on the
potential of water kefir, further research and industrial-scale production are
imperative.
... Loop-Pang has been reported to be cheap and highly efficient in starch hydrolysis. Hence, the existence of amylolytic activity suggests that bacteria, moulds, or yeast can liquefy and transform starch and starch-containing plant materials into maltodextrins, sugar syrups, dextrose, maltose, glucose, and other products (Liu et al., 2011;Reddy et al., 2008). The microbes subsequently convert the hydrolysates into metabolites such as organic acids, ethanol, and aromatic compounds (Hittinger et al., 2018). ...
The hydrolysis of starch is an important process used in various industries, including food, pharmaceuticals, and biofuels. It involves breaking starch molecules into simpler sugars, such as glucose and maltose, using enzymes or acid hydrolysis. Enzymatic hydrolysis is typically preferred due to its specificity and mild reaction conditions, while acid hydrolysis is faster but can result in a lower-quality product due to the formation of unwanted by-products. Various parameters, including pH, temperature, enzyme concentration, and substrate concentration, can affect the conversion of starch into reducing sugars. Also, these parameters can greatly affect the efficiency and yield of the hydrolysis process and must be carefully controlled to achieve optimal results. Hydrolyzed starch is highly soluble, stable, and easily fermentable. These unique properties make it a valuable ingredient in various applications, especially in food and beverages.KeywordsEnzyme hydrolysisAcid hydrolysisFermentationSaccharificationBiofuel
... Lactic acid, as one of the products of the selective oxidation of glycerol, has a wide range of applications across various fields, including food, materials, medicine, and daily life [14,15]. The global demand for lactic acid has exceeded its production, underscoring the significant application prospects for the selective oxidation of glycerol to lactic acid [16][17][18][19][20][21]. ...
Three types of CuO with different micro–structures were applied to catalyze the conversion of glycerol to lactic acid. The structure–activity relationship between CuO and its catalytic performance was investigated by combining experiments and theoretical calculations. We demonstrated that two CuO samples (CuO–BCC and CuO–CA), as prepared by calcining copper salts, show larger lattice spacing than that of commercial CuO (CuO–COM). In the catalytic experiments, CuO–BCC, which had the largest lattice spacing (d = 0.2480 nm), exhibited the highest yield of 78.54% for lactic acid. The lattice strain caused by lattice expansion was considered more favorable for CuO–BCC in adsorbing glycerol molecules, thereby improving the conversion of glycerol to lactic acid. The DFT simulation calculation results further prove that CuO–BCC has a larger adsorption energy for glycerol and a smaller thermodynamic energy barrier for the dehydrogenation of glycerol to form the key intermediate products (glyceraldehyde and 1,3-dihydroxyacetone) than CuO–COM. This study demonstrates the role of lattice strain effects in the development of catalysts and provides ideas for catalytic glycerol-selective oxidation studies.
... The effect of inulin (or non-digestible polysaccharides) is mainly mediated by the intestinal microbiome via the production of bacterial metabolites such as SCFA or lactate [50,51]. Moreover, a high CHO/protein ratio can affect the rainbow trout gut microbiota and in particular the rmicutes/proteobacteria ratio as well as the lactic-acid bacteria [6]. ...
Background
High dietary carbohydrates can spare protein in rainbow trout but may affect growth and health. Inulin, a prebiotic, could have nutritional and metabolic effects, along with anti-inflammatory properties in teleosts, improving growth and welfare. We tested this hypothesis in rainbow trout by feeding them a 100% plant-based diet, which is a viable alternative to fishmeal and fish oil in aquaculture feeds. In a two-factorial design, we examined the impact of inulin (2%) as well as the variation in the CHO/plant protein ratio on rainbow trout. We assessed the influence of these factors on zootechnical parameters, plasmatic metabolites, gut microbiota, production of Short-Chain Fatty Acid and lactic acid, as well as the expression of free-fatty acid receptors genes in the mid-intestine, intermediary liver metabolism, and immune markers.
Results
The use of 2% inulin did not change significantly the fish intestinal microbiota, while interestingly, the high CHO/Protein ratio group shows modification of intestinal microbiota and in particular the beta diversity, with 21 bacterial genera affected, including Ralstonia, Bacillus, and 11 lactic-acid producing bacteria. There were higher levels of butyric, and valeric acid in groups fed with high CHO/protein diet but not with inulin. The high CHO/Protein group shows a decrease in the expression of pro-inflammatory cytokines (il1b, il8, tnfa) in liver and a lower expression of the genes coding for tight-junction proteins in mid-intestine (tjp1a, tjp3). However, the 2% inulin did not modify the expression of plasma immune markers. Finally, inulin induced a negative effect on rainbow trout growth performance irrespective of the dietary carbohydrates.
Conclusions
with a 100% plant-based diet, inclusion of high levels of carbohydrates could be a promising way for fish nutrition in aquaculture through a protein sparing effect whereas the supplementation of inulin in combination with such alternative diets needs further investigations.
The current definition of a postbiotic is a “preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”. Postbiotics can be mainly classified as metabolites, derived from intestinal bacterial fermentation, or structural components, as intrinsic constituents of the microbial cell. Secondary bile acids deoxycholic acid (DCA) and lithocholic acid (LCA) are bacterial metabolites generated by the enzymatic modifications of primary bile acids by microbial enzymes. Secondary bile acids function as receptor ligands modulating the activity of a family of bile-acid-regulated receptors (BARRs), including GPBAR1, Vitamin D (VDR) receptor and RORγT expressed by various cell types within the entire human body. Secondary bile acids integrate the definition of postbiotics, exerting potential beneficial effects on human health given their ability to regulate multiple biological processes such as glucose metabolism, energy expenditure and inflammation/immunity. Although there is evidence that bile acids might be harmful to the intestine, most of this evidence does not account for intestinal dysbiosis. This review examines this novel conceptual framework of secondary bile acids as postbiotics and how these mediators participate in maintaining host health.
Characterizing starch-degrading Lactobacillaceae and associated enzymes remains relevant as various industries seek to harness their activity to produce valuable by-products, develop novel food applications, and to aid the sustainable bioconversion of starch-rich resources. To support this, we developed a targeted methodological and analysis framework utilizing complimentary phenomic and genomic assays informative of the starch degrading potential of Lactobacillaceae. Adapted starch agar plate assays incorporating diversified starch sources and states facilitated the rating of extracellular amylolytic activity by starch-processing-line isolates [Lactobacillus amylovorus (n = 3), Lactobacillus amylolyticus (n = 2), and Limosilactobacillus reuteri (n = 2)] as weak to moderate based on the complete or partial hydrolysis of retrograded soluble (SS), or potato and wheat (WS), starches, respectively, and the partial hydrolysis of raw SS. In contrast, the known raw starch degrader, L. amylovorus NRRL B4540, was rated as strong, with complete hydrolysis of all retrograded starch sources and raw WS. To explore genetic diversity and the putative enzymes associated with phenotypic diversity amongst L. amylovorus and L. amylolyticus, a multi-amplicon sequencing approach using MinION™ was used to simultaneously sequence starch-degradation-associated genes identified from them. Gene and deduced amino acid sequence analysis suggested raw starch hydrolysis by L. amylovorus NRRL B4540 was largely attributed to amyA encoding a rare α-amylase with unique starch binding domain (targeting α-1,4 linkages), but which was predicted to also require the starch debranching activity (targeting α-1,6 linkages) associated with (putative) pul-encoded pullulanase (Pul) for complete hydrolysis. Without amyA, Pul was hypothesized necessary for observed starch degradation by L. amylovorus and L. amylolyticus test isolates; as a previously undescribed amylopullulanase with dual activity, or as a pullulanase requiring complimentary α-1,4 activity from an additional enzyme, potentially Gly2 (a putative maltogenic α-amylase). Whilst further work is required to characterize these enzymes, including those encoded by gene variants, the experimental approach described here provided the necessary evidence to warrant this. Further, this framework is likely adaptable for the direct analysis of Lactobacillaceae-rich microbiomes for amylolytic potential and for the targeted screening of various other functions across different taxa.
Natural rubber is the bio-degradable matrix material obtained from trees. The use of natural rubber has gained insight for use in composites. This has created a huge impact on the replacement of traditional materials such as steel, alloys and polymer matrix composites. Natural fibres are also used as a reinforcement phase in such type of composites. Poly Latic Acid (PLA) is derived from renewable sources such as corn starch. In order to improve the specific properties of PLA composites, natural rubbers are integrated to form PLA/natural rubber composites. Polylactic acid based natural rubber composites are preferred for use in many engineering applications including aerospace, automobiles, household appliances etc. PLA is a nontoxic and eco-friendly material that is mostly preferred for use as an alternative for petroleum-based matrix such as polyester epoxy etc. It can be combined or used along with natural rubber for composites fabrication which results in good toughened composite. Nano particles, combined with natural rubber also have a great influence on the resulting properties. Their use can be expanded towards food packing applications also. In this work the use of natural rubber/synthetic rubber along with PLA for different applications are presented and elaborated. It can be found that the PLA based composites combined with natural/synthetic/nano-based materials has a wide potential application from low end house hold parts till high end aerospace applications.
In this chapter we provide some discussions on different topics such as cellulose-based rubber nanocomposites, cellulose based high performance rubber micro- or nano-composites, chitin based rubber bionanocomposites, chitin in rubber-based blends and micro composites, starch based bionanocomposites, polylactic acid based rubber composites and nanocomposite and bacterial cellulose/BC/rubber nanocomposites, cellulose in rubber-based blends and composites and applications of cellulose/rubber based bionanocomposites.
The article contains comprehensive information on groups of bacteria producing lactic acid, which have high metabolic activity and can be used in industrial production. In addition, an overview of the most common fermentation methods (batch, continuous, multiple), as well as cheap carbon sources: starch and cellulose-containing, industrial and food waste is provided.
Short-term adaptation of the microbiota could promote nutrient degradation and the host health. While numerous studies are currently undertaking feeding trials using sustainable diets for the aquaculture industry, the extent to which the microbiota adapts to these novel diets is poorly described. The incorporation of carbohydrates (CHO) within a 100% plant-based diet could offer a novel, cost-effective energy source that is readily available, potentially replacing the protein component in the diets. In this study, we investigated the short-term (3 weeks) effects of a high CHO, 100% plant-based diet on the mucosal and digesta associated microbiota diversity and composition, as well as several metabolic parameters in rainbow trout. We highlighted that the mucosa is dominated by Mycoplasma (44.86%). While the diets did not have significant effects on the main phyla (Proteobacteria, Firmicutes, Actinobacteria), after 3 weeks, a lower abundance of Bacillus genus, and higher abundances of four lactic-acid bacteria were demonstrated in digesta. In addition, no post-prandial hyperglycemia was observed with high carbohydrate intake. These results provide evidence for the rapid adaptation of the gut microbiota and host metabolism to high CHO in combination with 100% plant ingredients in rainbow trout.
In this study, lactic acid bacteria (LAB) were isolated from fresh milk samples from cow, sheep, and goat using MRS agar as a growth medium. Lactobacillusplantarum, Lactobacillusacidophilus, Lactobacillusfermentum, Enterococcusgallinarum, and Enterococcusfaecium were the species of LAB that were isolated and identified using the Vitek 2 compact system. While Lactobacillus fermentum, Enterococcus faecium, and Lactobacillus plantarum were isolated from goat milk, Lactobacillus acidophilus, Lactobacillus gallinarum, and Lactobacillus plantarum were isolated from cow milk.However, from sheep milk, only Lactobacillus plantarum and Lactobacillus acidophilus were isolated. All the isolates were subjected to amylase production test using modified MRS media and the results showed that Lactobacillus plantarum, Lactobacillusacidophilus and Lactobacillusfermentum produced amylase while Enterococcus gallinarum and Enterococcus faecium did not produce amylase.
Amino acids are the building blocks of proteins and are widely used as important ingredients for other nitrogen‐containing molecules. Here, we report the sustainable production of amino acids from biomass‐derived hydroxy acids with high activity under visible‐light irradiation and mild conditions, using atomic ruthenium‐promoted cadmium sulfide (Ru1/CdS). On a metal basis, the optimized Ru1/CdS exhibits a maximal alanine formation rate of 26.0 molAla·gRu‑1·h‑1, which is 1.7 times and more than two orders of magnitude higher than that of its nanoparticle counterpart and the conventional thermocatalytic process, respectively. Integrated spectroscopic analysis and density functional theory calculations attribute the high performance of Ru1/CdS to the facilitated charge separation and O‐H bond dissociation of the a‐hydroxy group, here of lactic acid. The operando nuclear magnetic resonance further infers a unique “double activation” mechanism of both the CH‐OH and CH3‐CH‐OH structures in lactic acid, which significantly accelerates its photocatalytic amination toward alanine.
Amino acids are the building blocks of proteins and are widely used as important ingredients for other nitrogen‐containing molecules. Here, we report the sustainable production of amino acids from biomass‐derived hydroxy acids with high activity under visible‐light irradiation and mild conditions, using atomic ruthenium‐promoted cadmium sulfide (Ru1/CdS). On a metal basis, the optimized Ru1/CdS exhibits a maximal alanine formation rate of 26.0 molAla ⋅ gRu⁻¹ ⋅ h⁻¹, which is 1.7 times and more than two orders of magnitude higher than that of its nanoparticle counterpart and the conventional thermocatalytic process, respectively. Integrated spectroscopic analysis and density functional theory calculations attribute the high performance of Ru1/CdS to the facilitated charge separation and O−H bond dissociation of the α‐hydroxy group, here of lactic acid. The operando nuclear magnetic resonance further infers a unique “double activation” mechanism of both the CH−OH and CH3−CH−OH structures in lactic acid, which significantly accelerates its photocatalytic amination toward alanine.
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This study investigated the effect of Lactobacillus acidophilus fermentation on plant-based aquafeed’s biochemical and nutritional profiles, as well as its impact on the productive performance and intestinal health of juvenile Nile tilapia (Oreochromis niloticus) reared in a biofloc system. Two fermentation times of 6 h and 18 h were assessed over 60 days and compared with positive and negative control diets containing fishmeal or devoid of animal protein, respectively. L. acidophilus fermentation improved the plant-based feed. Fish fed with the diet that was fermented for six hours exhibited improved survival rates. Fermentation worsened feed efficiency and increased feed intake. Fermented feeds positively influenced intestinal health by increasing beneficial bacteria and reducing pathogenic strains in both the rearing water and the fish’s guts. Fermented feeds also enhanced intestinal mucosa development compared to non-fermented diets. These results emphasize the promising impact of aquafeeds fermented with L. acidophilus on fish feeds and health and its sustainability by replacing the use of fishmeal with the use of plant protein.
Abstract
This study evaluated the effect of fermentation with Lactobacillus acidophilus on the biochemical and nutritional compositions of a plant-based diet and its effects on the productive performance and intestinal health of juvenile Nile tilapia (Oreochromis niloticus) reared in a biofloc technology (BFT) system. The in vitro kinetics of feed fermentation were studied to determine the L. acidophilus growth and acidification curve through counting the colony-forming units (CFUs) mL⁻¹ and measuring the pH. Physicochemical and bromatological analyses of the feed were also performed. Based on the microbial growth kinetics results, vegetable-based Nile tilapia feeds fermented for 6 (FPB6) and 18 (FPB18) h were evaluated for 60 days. Fermented diets were compared with a positive control diet containing fishmeal (CFM) and a negative control diet without animal protein (CPB). Fermentation with L. acidophilus increased lactic acid bacteria (LAB) count and the soluble protein concentration of the plant-based feed, as well as decreasing the pH (p < 0.05). FPB treatments improved fish survival compared with CPB (p < 0.05). Fermentation increased feed intake but worsened feed efficiency (p < 0.05). The use of fermented feeds increased the LAB count and reduced pathogenic bacteria both in the BFT system’s water and in the animals’ intestines (p < 0.05). Fermented plant-based feeds showed greater villi (FPB6; FPB18) and higher goblet cell (FPB6) counts relative to the non-fermented plant-based feed, which may indicate improved intestinal health. The results obtained in this study are promising and show the sustainable potential of using fermented plant-based feeds in fish feeding rather than animal protein and, in particular, fishmeal.
A photoredox‐neutral 1,2,5‐trifunctionalization of α‐hydroxyhexenoates is disclosed. The reaction proceeds through a sequence of radical addition, intramolecular heteroaryl migration, and radical‐polar crossover deuteration, leading to functionalized α‐deuterated lactic acid derivatives. The reaction features mild photochemical conditions and provides an efficient approach for the synthesis of valuable deuterated molecules. image
Banana weevil is a waste that has not been used much, however banana weevil has content lots of nutrition. So that need effort for utilise the banana weevil so that it can beneficial for society. This study used lactic acid bacteria fermentation method which aims to analyze the characteristics of modified banana weevil flour. Then thinly sliced banana weevil soaked for 2 hours inside sodium metabisulfite solution then soaked again use finished solution mixed with bacteria sour lactate with concentration 0;0,02;0,025;0,03 ml/L. After that hump dried and ground for become flour and tested characteristics. The results showed that the swelling power test level was highest at a concentration of 0.03 ml/L, which was 13.39 grams, the % solubility test was highest at a concentration of 0.03 ml/L with a value of 0.12%, the results of the viscosity test after being modified had the same value, namely of 1.4 mPa.s, for the results of reducing sugar content after being modified it decreased and a result of 4% was obtained.
Biopolymers obtained from renewable resources are an interesting alternative to conventional polymers obtained from fossil resources, as they are sustainable and environmentally friendly. Poly(lactic acid) (PLA) is a biodegradable aliphatic polyester produced from 100% renewable plant resources and plays a key role in the biopolymer market, and is experiencing ever-increasing use worldwide. Unfortunately, this biopolymer has some usage limitations when compared with traditional polymers; therefore, blending it with other biopolymers, such as poly(butylene succinate) (PBS), poly(butylene succinate-co-butylene adipate) (PBSA), poly(butylene adipate-co-butylene terephthalate) (PBAT) and different poly(hydroxyalkanoates) (PHA), is considered an interesting method to improve it significantly, customize its properties and extend the range of its applications. The following review highlights, in its first part, the physico-chemical and mechanical properties of PLA in comparison to the other biopolymers listed above, highlighting the various drawbacks of PLA. The second part of the review deals with recent developments, results, and perspectives in the field of PLA-based blends.
This study investigated the impact of initial culture media pH on the antibacterial properties and metabolic profile of cell-free supernatants (CFSs) from Lactobacillus acidophilus BIOTECH 1900 (LAB1900). The CFSs harvested from LAB1900 grown in de Man, Rogosa, Sharpe broth with initial pH of 5.5 (CFS5.5) and 6.6 (CFS6.6) were tested. The two CFSs elicited varying degrees of activity against three gram-negative bacteria. In the agar-well diffusion against Pseudomonas aeruginosa, CFS5.5 and CFS6.6 recorded 14.36 ± 1.34 and 13.06 ± 1.29 mm inhibition, respectively. Interestingly, against Klebsiella pneumoniae, CFS5.5 showed 14.36 ± 1.56 mm inhibition which was significantly higher than the 12.22 ± 1.31 mm inhibition of CFS6.6 (p = 0.0464). While against Acinetobacter baumannii, significantly higher inhibition of 10.66 ± 0.51 mm was observed in CFS6.6 compared to the 7.58 ± 1.93 mm inhibition of CFS5.5 (p = 0.0087). Nonetheless, both CFSs were bactericidal, with a minimum inhibitory and bactericidal concentration range of 3.90625-7.8125 mg/mL. The varied antibacterial activities may be attributed to the metabolite compositions of CFSs. A total of 152 metabolites driving the separation between CFSs were noted, with the majority upregulated in CFS5.5. Furthermore, 15 were putatively identified belonging to acylcarnities, vitamins, gibberellins, glycerophospholipids, and peptides. In summary, initial culture media pH affects the production of microbial metabolites with antibacterial properties.
The awareness of the severe environmental consequences of petroleum-based plastics has expanded globally. Therefore, academic and industrial researchers have been extremely encouraged to investigate replacing traditional petrochemical-based plastic products with biobased and biodegradable alternatives in order to minimize fossil fuel consumption. Among the biopolymers available nowadays, polylactic acid (PLA) is one of the tops produced and seems to be a promising candidate to commercially replace many nondegradable polymers. Although PLA offers comparable mechanical properties, inherent biodegradable character, and renewable biobased nature, PLA-based materials still need lots of studying and development. This chapter will highlight the most critical properties of PLA after providing a brief overview of its origin and production processes. The challenges and drawbacks that limit PLA processing and applications will be discussed in-depth as well. The chapter will mainly shed light on the PLA-based bionanocomposites and discuss their classifications, processing, and how nanotechnology can significantly develop neat PLA performance. At the end of the chapter, some of the most recent applications of the PLA-based bionanocomposites will be represented considering many fields such as food packaging, shape memory polymers, and medical tools for COVID-19 fighting.
In the food, chemical, and pharmaceutical industries, macromolecules like amino acids, vitamins, and metabolites generated by microorganisms using renewable feedstocks are significant due to their low cost and sustainability. In addition to their conventional uses, these are also employed in emerging research fields like the production of bioplastics and aesthetic surgeries. These macromolecules can be manufactured commercially using chemical and biological processes, which is an efficient and environmentally benign technique. Microbial solid cell factories with exceptional resistance to extreme pH conditions, large concentrations of metabolites, and lignocellulosic inhibitors are required for an economically feasible fermentation process. Strain improvement and metabolic engineering are two techniques that can be used to create strains with high productivity. This chapter discusses the biosynthetic pathways, substrates, strain improvement, and upstream techniques for methionine l-glutamate, l-lysine, vitamins B2 and B12, coenzyme Q10 or ubiquinone, lactic acid, itaconic acid, and hyaluronic acid as well as their market perspective and budding challenges.KeywordsAmino acidsVitaminsMetabolitesMicroorganismsFermentationPurification
Acrylamide (AA), as a food-borne toxicant, is created at some stages of thermal processing in the starchy food through Maillard reaction, fatty food via acrolein route, and proteinous food using free amino acids pathway. Maillard reaction obviously takes place in thermal-based products, being responsible for specific sensory attributes; AA formation, thereby, is unavoidable during the thermal processing. Additionally, AA can naturally occur in soil and water supply. In order to reduce the levels of acrylamide in cooked foods, mitigation techniques can be separated into three different types. Firstly, starting materials low in acrylamide precursors can be used to reduce the acrylamide in the final product. Secondly, process conditions may be modified in order to decrease the amount of acrylamide formation. Thirdly, post-process intervention could be used to reduce acrylamide. Conventional or emerging mitigation techniques might negatively influence the pleasant features of heated foods. The current study summarizes the effect of enzymatic reaction induced by asparaginase, glucose oxidase, acrylamidase, phytase, amylase, and protease to possibly inhibit AA formation or progressively hydrolyze formed AA. Not only enzyme-assisted AA reduction could dramatically maintain bio-active compounds, but also no damaging impact has been reported on the sensorial and rheological properties of the final heated products. The enzyme engineering can be applied to ameliorate enzyme functionality through altering the amino acid sequence like site-specific mutagenesis and directed evolution, chemical modifications by covalent conjugation of L-asparaginase onto soluble/insoluble biocompatible polymers and immobilization. Moreover, it would be possible to improve the enzyme's physical, chemical, and thermal stability, recyclability and prevent enzyme overuse by applying engineered ones. In spite of enzymes' cost-effective and eco-friendly, promoting their large-scale usages for AA reduction in food application and AA bioremediation in wastewater and soil resources.
Eight starch hydrolyzing and lactic acid producing strains have been isolated from corn starch processing industrial wastes. The isolates are anaerobic, Gram positive, non-spore forming and rod shaped bacteria having growth at 15 degrees C with extracellular amylolytic activity. Based on these features the isolates have been identified as Lactobacillus amylophilus. Among these, three strains GV6, GV7 and GV8, produce 9.1, 8.8 and 8.1 g/L lactic acid from 9.3, 9.2 and 8.7 g/L soluble starch respectively. The growth is observed at a wide range of temperature and pH, with an optimum temperature of 40 degrees C and pH 6.0. The conversion of starch to lactic acid by the isolates would reduce the cost of hydrolysis of starch to glucose, prior to fermentation.
Lactic acid production by an amylolytic bacterium Lactobacillus amylophilus GV6 is studied using wheat bran in solid state fermentation. Conditions of solid state fermentations are optimized. Moisture content 83 per cent, at 37°C, pH 6.75, inoculum size 3.5 mL and incubation period of 5 d were found to be optimum. Different brans of pigeon pea, green gram, black gram and corn fibre are also tested in addition to wheat bran. Wheat bran is found to be the best as solid support and substrate among all brans tested.
Lactobacillus amylophilus GV6 was studied for L(+) lactic acid production in solid state fermentation. The physical parameters, such as moisture, temperature, pH, inoculum size, incubation period, total N content and buffering agent (CaCO3), were studied using the Taguchi statistical methods to observe the interaction effects and identify the vital factors governing the process of fermentation beneficial in further improvement of lactic acid production. Moisture is identified to be the important physical parameter, showing maximum impact at 83%, along with temperature 37°C, pH 6.5, inoculum size 9 mL, incubation period 9 days, total N content 2% and CaCo3 1.5 g/10 grams of substrate (wheat bran).
Lactobacillus amylophilus GV6 was used for direct fermentation of raw starch in wheat bran to L(+) lactic acid in semi-solid state fermentation. At m/V ratio of wheat bran 9 % (9 g of wheat bran in 100 mL of medium) with m/V ratio of CaCO 3 0.375 %, 2.5 g of L(+) lac-tic acid was produced. To maximize the production of lactic acid, process variables like the volume of inoculum and incubation period were optimized keeping m/V ratio of wheat bran and CaCO 3 at 9 and 0.375 %, respectively, and constant pH=6.5, using response sur-face method (RSM). The organism produced 3.5 g of L(+) lactic acid from 3.96 g of starch present in 9 g of wheat bran. Maximum starch conversion to lactic acid was observed at process conditions of wheat bran m/V ratio 9 % at 37 °C, pH=6.5, inoculum volume 3.5 mL and incubation period of 130 h.
L. amylophilus GV6 was studied for production of L(+) lactic acid in single step fer-mentation using starchy substrates. Seven types of inexpensive organic nitrogen supple-ments (flour of pigeon pea, red lentil gram, black gram, bengal gram, green gram, soya bean and baker's yeast) were evaluated for their potential to replace more expensive com-mercial nitrogen sources, peptone and yeast extract. Red lentil and baker's yeast cells were found to be the best alternative nutrient sources of peptone and yeast extract for lactic acid production. L(+) lactic acid yield was about 92 % m(lactic acid)/m(starch) utilized in this study.
Lactic acid is widely used in the food, cosmetic, pharmaceutical, and chemical indus-tries and has received increased attention for use as a monomer for the production of bio-degradable poly(lactic acid). It can be produced by either biotechnological fermentation or chemical synthesis, but the former route has received considerable interest recently, due to environmental concerns and the limited nature of petrochemical feedstocks. There have been various attempts to produce lactic acid efficiently from inexpensive raw materials. We present a review of lactic acid-producing microorganisms, raw materials for lactic acid production, fermentation approaches for lactic acid production, and various applications of lactic acid, with a particular focus on recent investigations. In addition, the future po-tentials and economic impacts of lactic acid are discussed.
Twelve amylolytic heterofermentative lactic acid bacteria were isolated in Benin from the fermentation processes of maize sour dough, namely ogi and mawè. Discrimination of strains was performed by DNA restriction patterns and compared with carbohydrate fermentation profiles. This allowed two new amylolytic strains, Ogi E1 and Mw2, belonging to the species Lactobacillus fermentum, to be distinguished. Strains Ogi E1 and Mw2 presented different amylolytic activities; amylase from strain Mw2 was more acidophilic and mesophilic than amylase produced by strain Ogi E1.
Production of lactic acid from beet molasses by Lactobacillus delbrueckii NCIMB 8130 in static and shake flask fermentation was investigated. Shake flasks proved to be a better fermentation system for this purpose. Substitution of yeast extract with other low cost protein sources did not improve lactic acid production. The maximum lactic acid concentration was achieved without treatment of molasses. A Central Composite Design was employed to determine the maximum lactic acid concentration at optimum values for the process variables (sucrose, yeast extract, CaCO3). A satisfactory fit of the model was realized. Lactic acid production was significantly affected both by sucrose–yeast extract and sucrose–CaCO3 interactions, as well as by the negative quadratic effects of these variables. Sucrose and yeast extract had a linear effect on lactic acid production while the CaCO3 had no significant linear effect. The maximum lactic acid concentration (88.0 g/l) was obtained at concentrations for sucrose, yeast extract and CaCO3 of 89.93, 45.71 and 59.95 g/l, respectively.
Lactobacillus amylophilus strain GV6, isolated from corn starch processing industrial wastes, was amylolytic and produced 0.96 g L(+) lactic acid per gram of soluble starch. The optimum temperature and pH for growth and L(+) lactic acid production were 37 C and 6.5, respectively. At low substrate concentrations, the lactic acid production on corn starch was almost similar to soluble starch. The strain is fermenting various naturally available starches directly to lactic acid. The total amylase activity of the strain is 0.59 U/ml/min. The strain produced 49 and 76.2 g/l L(+) lactic acid from 60 g/l corn starch and 90 g/l soluble starch, respectively. This is the highest L(+) lactic acid among the wild strains of L. amylophilus reported so far.
Lactobacillus cellobiosus, isolated from city wastes, produced an extracellular alpha-amylase and produced lactic acid by direct fermentation of waste potato mash. Using a 5% (w/v) potato mash with 3% (w/v) CaCO to neutralise the lactic acid produced, 50% conversion of starch to lactic acid occurred in 48 h without any other media supplement.
An alternative process for industrial lactic acid production was deveooped using a starch degrading lactic acid producing organism,Lactobacillus amylovorus B-4542. In this process, saccharification takes place during the fermentation, eliminating the need for complete hydrolysis of the starch to glucose prior to fermentation. The cost savings of this alternative are substantial since it eliminates the energy input, separate reactor tank, time, and enzyme associated with the typical pre-fermentation saccharification step. The only pre-treatment was gelatinization and enzyme-thinning of the starch to overcome viscosity problems associated with high starch concentrations and to make the starch more rapidly degradable. This fermentation process was optimized for temperature, substrate level, nitrogen source and level, mineral level, B-vitamins, volatile fatty acids, pH, and buffer source. The rate of the reaction and the final level of lactic acid obtained in the optimized liquefied starch process was similar to that obtained withL. delbrueckii B-445 using glucose as the substrate.
Lactobacillus amylophilus GV6 fermented a variety of pure and natural starches directly to L(+) lactic acid. Starch to lactic acid conversion efficiency was more than 90% by strain GV6 at low substrate concentrations with all starches. The strain GV6 produced high yields of lactic acid per g of substrate utilized with pure starches such as soluble starch, corn starch, and potato starch, yielding 92–96% at low substrate concentrations in 2 days and 78–89% at high substrate (10%) concentrations in 4–6 days. Strain GV6 also produced high yields of lactic acid per g of substrate utilized with crude starchy substrates such as wheat flour, sorghum flour, cassava flour, rice flour and barley flour yielding 90–93% at low substrate concentrations in 2 days and 80% or more at high substrate concentrations in 6–7 days. Lactic acid yields by L. amylophilus GV6 with pure starches were comparable when low cost crude starchy substrates were used. Lactic acid productivity by strain GV6 is higher than for any other previously reported strains of L. amylophilus.
While lactic acid-producing fermentation has long been used to improve the storability, palatability, and nutritive value of perishable foods, only recently have we begun to understand just why it works. Since the publication of the third edition of Lactic Acid Bacteria: Microbiological and Functional Aspects, substantial progress has been made in a number of areas of research. Completely updated, the Fourth Edition covers all the basic and applied aspects of lactic acid bacteria and bifidobacteria, from the gastrointestinal tract to the supermarket shelf. Topics discussed in the new edition include: • Revised taxonomy due to improved insights in genetics and new molecular biological techniques • New discoveries related to the mechanisms of lactic acid bacterial metabolism and function • An improved mechanistic understanding of probiotic functioning • Applications in food and feed preparation • Health properties of lactic acid bacteria • The regulatory framework related to safety and efficacy Maintaining the accessible style that made previous editions so popular, this book is ideal as an introduction to the field and as a handbook for microbiologists, food scientists, nutritionists, clinicians, and regulatory experts.
A study is performed on the demand of lactic acid in the market. The lactic acid market is experiencing healthy growth across the board, with consumer interest in food safety and mineral fortification boosting sales in food applications and industrial applications. It is reported that growth in industrial applications has been so strong that the segment is challenging the food and beverage segment as the leading consumer of lactic acid in the U.S..
Lactic acid bacteria were isolated from soil by enrichment culture technique using anaerobically digested molasses spent wash (ADMSW), which was obtained from a biomethanation plant. The bacterial isolates could grow in 25% (v/v) ADMSW medium supplemented with 2% carbon, 4% moong bean sprouts (w/v) and 0.15% diammonium phosphate. Due to fermentation, there was reduction of COD by 41% and colour by 57% in the effluent. During the bioremediation process, lactic acid with an average yield of 15.4 gL-1 was obtained as a byproduct.
L. amylophilus GV6 was studied for production of L(+) lactic acid in single step fermentation using starchy substrates. Seven types of inexpensive organic nitrogen supplements (flour of pigeon pea, red lentil gram, black gram, bengal gram, green gram, soya bean and baker's yeast) were evaluated for their potential to replace more expensive commercial nitrogen sources, peptone and yeast extract. Red lentil and baker's yeast cells were found to be the best alternative nutrient sources of peptone and yeast extract for lactic acid production. L(+) lactic acid yield was about 92 % m(lactic acid)/m(starch) utilized in this study.
The commercial production of lactic acid via fermentation began in 1881 and continues today. Today, because of the rising cost of petrochemical feedstocks and the recent establishment of better commercial scale recovery methods for fermentation acid, the outlook for the process looks more favorable. A discussion is given on the production technology of lactic acid: microorganisms and raw materials; fermentation processes; recovery processes; and synthetic manufacture. The discussion ends with a look at the economics of lactic acid: market size, manufacturers, prices, uses, and applications.
Although this chapter is devoted to milk and other dairy products, it begins with a discussion of fermentation because of the importance of this process to dairy products.
Parameters affecting the fermentative lactic acid (LA) production are summarized and discussed: microorganism, carbon- and nitrogen-source, fermentation mode, pH, and temperature. LA production is compared in terms of LA concentration, LA yield and LA productivity. Also by-product formation and LA isomery are discussed.
Fermentation production of lactic acid directly from starch was studied in a membrane recycle bioreactor (MRB) using Lactobacillus amylovorus. With 50 g litre−1 liquefied starch as feed, essentially complete conversion to lactic acid was obtained up to a dilution rate of 0·2h−1; maximum productivity of 25 g litre−1 h−1 was obtained at 0·5 h−1. A higher starch concentration in the feed caused lower conversions, resulting in rapid accumulation of unconverted starch in the fermenter. The MRB was operated continuously for 10 days without significant problems. Media components were responsible for fouling the membrane module.
For the production of lactic acid by Lactobacillus plantarum NCIM 2084, response surface methodology (RSM) using central composite rotatable design (CCRD) was adopted for optimising the media composition with respect to liquefied starch, wheat bran extract, ammonium nitrate and sodium acetate. A set of 28 experiments were carried out and cannonical analysis was employed. Significant (p ≤ 0.25) effects were observed for the first three variables. Quadratic and interaction effects of the variables were more prominent than the linear effects. The respective optimum concentrations obtained were 9.99, 0.05, 2.48 and 0.08% giving a substrate conversion of 92% and a lactic acid concentration of 72.9 g/L in 24 h. It has been possible to replace the expensive yeast extract by. a combination of wheat bran extract and ammonium nitrate.
Lactic acid can be used not only as a key substance in chemical synthesis, but also as a special agent in agriculture. For microbial production, original products of agriculture such as sweet sorghum stalks and rye grains can be used as raw material. In laboratory experiments, sweet sorghum stalks were milled, steam-treated and pressed. The sugar of the aqueous extract, which amounted to 89% of the total sugar of stalks, was completely converted into lactic acid by fermentation. The yield amounted to 94% (94 g of lactic acid/100 g of sugar consumed). Also in laboratory experiments, rye grains were milled, fractionated and hydrolyzed in a two-step process using commercial enzymes. The optimum temperature and pH value were 82·5°C and 5·8 for starch liquefaction and 51·6°C and 4·0 for saccharification of liquefied starch, respectively. Starch liquefaction was also influenced by particle size, the optimum value of which was 3 mm. For optimum starch saccharification, a process duration of 2 h was necessary. Of the solid starch, 99·6% was liquefied in the first hydrolysis step. In the second step, 97·9% of the liquefied starch was converted into glucose. Bioconversion of the glucose formed by starch hydrolysis into lactic acid also gave a maximum yield of 94%. Various possibilities of process improvement in order to make the whole operation less expensive are discussed, and a flow-sheet of an improved process for manufacturing lactic acid from cereals is presented.
Summary Fermentation production of lactic acid directly from starch was studied in a batch fermentor usingLactobacillus amylovorus. At an initial concentration of 120 g/L starch, 96.2 g/L of lactic acid was produced from liquefied starch in 20 hours while 92.5 g/L of lactate was produced from the raw starch in 39 hours. High initial glucose levels (100 g/L) in the medium inhibited the organism, unless it had been adapted by growing it in a low-glucose medium. The direct production of lactic acid from starch could reduce overall production costs significantly.
Summary Rhizopus oryzae NRRL 395 was found capable of fermenting ground corn directly to L(+)-lactic acid in the presence of calcium carbonate. The average yield of L(+)-lactic acid was more than 44% on the basis of the amount of total carbohydrate as glucose consumed.
A brew (1 rye flour: 2 water) was fermented by its indigenous microflora at temperatures (T) of 10, 15, 20, 25, 30, 35 and 40°C. A direct relationship was observed between the fermentation temperature and the absolute values of the ‘b' (the t coefficient) and ‘c' (an indicator of the width of the parabola) parameters of the fitted quadratic equations: pH=a+bt+ct2. Setting the first derivative of the quadratic fitted function to zero, dpH/dt=b+2ct=0, and solving for t gives the duration of the lag-phase period. When the temperature was increased from 10 to 35°C, the lag phase period (no net change in pH) of the fermentation was reduced by >sixfold from 17.8–2.9 h and the fermentation time to attain a pH of 5.0 was reduced by >13 times from 132–9.9 h. The fermentation rate (F) of rye flour within each of the three periods increased as the fermentation temperature increased up to 35°C. To predict the fermentation time to pH 5.0 at temperatures other than these examined in this study but within the range of these temperatures an exponential function, t5.0={exp[a+(b×T0.5)+c×exp(−T)}, was fitted. The Arrhenius plot of the acid production rate ([H+] h−1) vs the reciprocal of the absolute temperature showed a ‘breakpoint' at 15°C; indicating that 15°C may be the minimum metabolically efficient temperature for the lactic acid fermentation of rye flour. The activation energy (Ea) was 1.4 and 16.0 cal mol−1above and below the 15°C breakpoint; an additional indication that at temperatures
Lactic acid bacteria (LAB) constitute a group of gram-positive bacteria united by a constellation of morphological, metabolic, and physiological characteristics. The general description of the bacteria included in the group is gram-positive, nonsporing, nonrespiring cocci or rods, which produce lactic acid as the major end product during the fermentation of carbohydrates. The LAB term is intimately associated with bacteria involved in food and feed fermentation, including related bacteria normally associated with the (healthy) mucosal surfaces of humans and animals. The boundaries of the group have been subject to some controversy, but historically the genera Lactobacillus, Leuconostoc, Pediococcus, and Streptococcus form the core of the group. Taxonomic revisions of these genera and the description of new genera mean that LAB could, in their broad physiological definition, comprise around 20 genera. However, from a practical, food-technology point of view, the following genera are considered the principal LAB: Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Oenococcus, Pediococcus, Streptococcus, Tetragenococcus, Vagococcus, and Weissella. The genus Bifidobacterium, often considered in the same context as the genuine lactic acid bacteria and sharing some of their typical features, is phylogenetically unrelated and has a unique mode of sugar fermentation. The classification of lactic acid bacteria into different genera is largely based on morphology, mode of glucose fermentation, growth at different temperatures, configuration of the lactic acid produced, ability to grow at high salt concentrations, and acid or alkaline tolerance. Chemotaxonomic markers such as fatty acid composition and constituents of the cell wall are also used in classification. In addition, the present taxonomy relies partly on true phylogenetic relationships, which have been revealed by extensive work on determining rRNA sequences. Some of the newly described genera are most easily determined with oligonucleotide probes, polymerase chain reaction (PCR)–based technologies using these sequences, or direct sequencing of the 16S rRNA gene. Most genera in the group form phylogenetically distinct groups, but for some, in particular Lactobacillus and Pediococcus, the phylogenetic clusters do not correlate with the current classification based on phenotypic characters. New tools for classification and identification of LAB are currently replacing and/or complementing the traditional phenotype-based methodologies. The most promising for routine use are 16S rRNA gene sequencing, PCR-based fingerprinting techniques and soluble protein patterns.
Lactic acid, the most widely occurring hydroxycarboxylic acid, is an enigmatic chemical. It was discovered a long time ago and its use in food preservation and processing and as a specialty chemical has grown over the years with current production of about 120 000 t yr−1. Its potential as a major chemical feedstock, derived from renewable carbohydrates by sustainable technologies, to make plastics, fibers, solvents and oxygenated chemicals, had also been recognized. Recently, new technologies have emerged that can overcome major barriers in separations and purification and processing. Advances in electrodialysis (ED) and bipolar membranes and one particular process configuration termed the `double ED' process, a specific combination of desalting ED followed by `water-splitting' ED with bipolar membranes, has given very promising results, showing a strong potential for an efficient and economic process for recovery and purification of lactic acid without generating a salt waste. For the production of polymers, several advances in catalysts and process improvements have occurred in the technology to produce dilactide and its polymerization to produce plastics and fibers by Natureworks LLC, which is the leader in lactic polymer technology and markets. Other advances in esterification technology with pervaporation and development of biosolvent blends also have a high potential for `green' solvents in many applications. Recently, a considerable amount of pioneering effort in technology, product development and commercialization has been expended by several companies. To overcome the barriers to replace long-established petroleum-derived products, further real support from consumer, regulatory and government organizations is also needed. Copyright © 2006 Society of Chemical Industry
Lactic acid was produced from pretreated beet molasses by the homofermentative organism Lactobacillus delbrueckii subsp delbrueckii IFO 3202 entrapped in calcium alginate gel using batch, repeated batch and continuous fermentation systems. In batch fermentation studies successful results were obtained with 2.0–2.4 mm diameter beads prepared from 2% sodium alginate solution. The highest effective yield (82.0%) and conversion yield (90.0%) were obtained from substrate concentrations of 52.1 and 78.2 g dm−3 respectively. The gel beads produced lactic acid for 14 consecutive batch fermentations without marked activity loss and deformation. In the continuous fermentation, the highest lactic acid (4.22%) was obtained at a dilution rate of 0.1 h−1 while the highest productivity (13.92 g dm−3 h−1) was obtained at a dilution rate of 0.4 h−1.© 1999 Society of Chemical Industry
In Brazil and Colombia, ‘sour starch’ is traditionally obtained by a submerged lactic fermentation of crude cassava starch followed by sun drying. It is used by local bakers to prepare breadlike products which display the same expanded crumb texture as in wheat bread.
In this process, suspended starch is settled down and left aside for a few weeks under anaerobic conditions where natural lactic populations develop.
Three collections of clones isolated from local fermentations have been identified using the API procedure and further characterized. Most of them belong to different species of Lactobacillus. Many display a ropy phenotype, typical for exopolysaccharide (EPS) excretion. A possible role of these EPS in the special properties of sour starch is discussed.
Process variables were optimized for the production of lactic acid from pretreated beet molasses by Lactobacillus delbrueckii IFO 3202 for batch and continuous fermentations. In the batch fermentation, maximum yields (95·4% conversion, 77·1% effective) and maximum lactic acid volumetric productivity (4·83 g dm−3 h−1) was achieved at 45°C, pH 6·0, 78·2 g dm−3 sugar concentration with 10 g dm−3 yeast extract. Various cheaper nitrogen sources were replaced with yeast extract on equal nitrogen bases in batch fermentation. Of all the nitrogen sources tested, yeast extract yielded the highest and malt sprouts yielded the second highest level of lactic acid. In the continuous fermentation, maximum lactic acid (4·15%) was obtained at a dilution rate of 0·1 h−1. Maximum volumetric lactic acid productivity (11·20 g dm−3 h−1) occurred at D = 0·5 h−1 dilution rate. © 1997 SCI.
The amylase activity of twenty strains of Lactobacillus species isolated from intestinal contents of pigs was studied in vitro. Hydrolysis of starch was measured by following the disappearance of starch in a broth medium during the growth of all three strains. The amount of enzyme activity varied among strains. Three strains (A-4, L9 and L23) were selected for further study based on their high amylolytic activity in a broth containing soluble starch as the only carbohydrate source. Strains A-4 and L23 were identified as L. acidophilus and strain L9 was identified as L. fermentum. Among the three cultures, L. acidophilus L23 was selected as a potential candidate for use as a probiotic for improving digestion of starch in pigs based on its growth and hydrolysis of raw starch. The enzyme activity of L. acidophilus L23 was associated with the cell envelope and that of L. fermentum L9 was extracellular. The enzyme activity of L. acidophilus A4 was found in both locations. The enzyme activity of L. acidophilus L23 was inducible rather than constitutive.
Sweet sorghum was used as the raw material for the lactate production by a strain of Lactobacillus paracasei. The submerged conversion of sugar juice obtained from sweet sorghum by extraction could be accomplished with the same efficiency as observed in a control experiment with MRS-glucose medium (final lactate concentration of 88–106 g/l, lactate yield of 91–95%, duration of the fermentation of 24–32 h). Finely ground stalks of sorghum served as the substrate in the solid-state fermentation. The lactate accumulation in the solid medium and the lactate yield were optimized up to values comparable with the results from the submerged fermentation (final lactate concentration of 90 g/kg, lactate yield of 91–95%). However, the duration of the fermentation amounted to 120–200 h in the solid-state process. The data from a series of experiments performed at variable values of temperatures between 30°C and 36°C and initial sugar concentrations between 60 g/kg and 115 g/kg, and degrees of moisture between 78% and 82% was the basis of a polynomial multidimensional regression. As a result, simple three-dimensional model functions were obtained for the maximum productivity of lactate formation, the lactate yield and the time required for a 90% conversion.
IntroductionClassificationMorphology and PropagationProcurement and CultivationProduction of Useful MetabolitesPerspectivesReferences
Lactic acid has been an intermediate-volume specialty chemical (world production ∼ 40,000 tons/yr) used in a wide range of food processing and industrial applications. Lactic acid has the potential of becoming a very large volume, commodity-chemical intermediate produced from renewable carbohydrates for use as feedstocks for biodegradable polymers, oxygenated chemicals, plant growth regulators, environmentally friendly ‘green’ solvents, and specialty chemical intermediates. The recent announcements of new development-scale plants for producing lactic acid and polymer intermediates by major U.S. companies, such as Cargill, Ecochem (DuPont/ConAgra), and Archer Daniels Midland, attest to this potential.
In the past, efficient and economical technologies for the recovery and purification of lactic acid from crude fermentation broths and the conversion of lactic acid to the chemical or polymer intermediates had been the key technology impediments and main process cost centers. The development and deployment of novel separations technologies, such as electrodialysis (ED) with bipolar membranes, extractive distillations integrated with fermentation, and chemical conversion, can enable low-cost production with continuous processes in large-scale operations. The use of bipolar ED can virtually eliminate the salt or gypsum waste produced in the current lactic acid processes. Thus, the emerging technologies can use environmentally sound processes to produce environmentally useful products from lactic acid. The process economics of some of these processes and products can also be quite attractive. In this paper, the recent technical advances in lactic and polyactic acid processes are discussed. The economic potential and manufacturing cost estimates of several products and process options are presented. The technical accomplishments at Argonne National Laboratory (ANL) and the future directions of this program at ANL are discussed.
The biosynthesis of ammonium lactate, a product of lactic acid fermentation was studied from corn and glucose at five different pH values of 5.4 to 7.8. In the glucose fermentations, a 100% conversion of substrate was obtained resulting in a maximum lactic acid production yield of 93.2%. The optimum pH for the maximum volumetric rate of lactic acid biosynthesis (1.56 g dm−3 h−1) was between 6.0 and 6.5. The corn fermentations were slower than the glucose fermentations with a resulting lactic acid yield of 67.5%. Hydrolysis of corn by enzymatic or chemical methods as well as the use of ammonium hydroxide for pH control increased both the final concentration and the rates of lactic acid production. An enhanced yield of more than 90% was finally obtained in the corn fermentations. A logistic model adequately described the kinetics of biomass growth, lactic acid production and sugar utilization in the glucose fermentations at different pH values. The dynamics of lactic acid formation in the corn fermentations were also successfully described by the developed model. The dependence of the model parameters on pH was investigated.
An ∝aL-amylase activity has been observed in lactic acid bacteria occurring initially in fermented fish silage. The organisms belong to the genus Leuconostoc. The main fraction of the amylolytic enzyme produced by one of the isolated bacteria is cell-bound and is released into the medium at a late stage of growth. Treating cells with ultrasound or Triton X-100 increases enzyme activity in the culture filtrate. The pH range for enzyme activity is 5.0–7.0, with an optimum at pH 6.0. The enzyme is extremely labile at pH 8.0 and is inactivated at temperatures above 50°C at pH 5.8. Two enzyme fractions were found by isoelectric focusing, the main one at pH 5.00 and another at pH 4.5. Chromatography on DEAE cellulose gave two active peaks.
Separation of amplified V3 region from 16S rDNA by denaturing gradient gel electrophoresis (DGGE) was tested as a tool for
differentiation of lactic acid bacteria commonly isolated from food. Variable V3 regions of 21 reference strains and 34 wild
strains referred to species belonging to the genera Pediococcus, Enterococcus, Lactococcus, Lactobacillus, Leuconostoc, Weissella, and Streptococcus were analyzed. DGGE profiles obtained were species-specific for most of the cultures tested. Moreover, it was possible to
group the remaining LAB reference strains according to the migration of their 16S V3 region in the denaturing gel. The results
are discussed with reference to their potential in the analysis of LAB communities in food, besides shedding light on taxonomic
aspects.
Microorganisms which produce strong raw-starch degrading enzymes were isolated from soil using a medium containing a unique carbon source, -amylase resistant starch (-RS), which is insoluble in water and hardly digested with Bacillus amyloliquefaciens -amylase. Among the isolates, three strains showing high activities were characterized. Two of them, K-27 (fungus) and K-28 (yeast), produced -amylase and glucoamylase, and the final product from starch was only glucose. The third strain, K-2, was a bacterium and produced -amylase, which produced glucose and malto-oligosaccharides from starch. The enzyme preparation of these strains degraded raw corn starch rapidly.
Organisms isolated during the fermentation of cassava tubers, as practised for fufu production, includedBacillus subtilis, Pseudomonas alcaligenes, Lactobacillus plantarum, Corynebacterium manihot, Leuconostoc mesenteroides andPseudomonas aeruginosa. All isolates displayed amylase activity. Optimum growth and amylase activities of isolated organisms was at 42C and between pH values 5 and 6. Isolated organisms also displayed similar patterns of antibiotic resistance. Plasmids purified from isolates could not be transferred or maintained inEscherichia coli RR1 cells.La fermentation des tubercules de manioc a t effectue comme on le pratique traditionnellement pour la production de fufu. On a utilis quatre varits diffrentes de tubercules de manioc. Au cours du processus de fermentation, un grand nombre d'espces microbiennes agissent de concert pour dgrader l'amidon contenu dans les tubercules. Les glycosides cyanognes, linamarine et lotaustraline sont galement degrads. Les microorganismes isols au cours de la fermentation des tubercules de manioc, comme on la pratique pour la production de fufu, comprennentBacillus subtilis, Pseudomonas alcaligenes, Lactobacillus plantarum,Corynebacterium manihot, Leuconostoc mesenteroides andPseudomonas aeruginosa. Tous les microorganismes isols rvlent une activit amylolytique. Les croissances et activits amylolytiques des microorganismes isols montrent un optimum 42C et un pH entre 5 et 6. Les organismes isols exhibent aussi des profils semblables de rsistance aux antibiotiques. Les plasmides purifis des isolats n'ont pas pu tre transfrs ni maintenus dans des cellules d'Escherichia coli RR1.
Lactobacillus casei subsp. casei CFTRI 2022 produced a higher concentration of lactic acid (5.27 g/100 g dry sugar-cane pressmud) in a solid-state fermentation (SSF) system as compared to L. helveticus CFTRI 2026 and Streptococcus thermophilus CFTRI 2034. The lactic acid production by L. casei subsp. casei CFTRI 2022 was found to be significantly influenced by the initial moisture content, initial pH and initial sugar concentration of the medium. Studies on four inert materials to reduce the initial sugar concentration in the medium showed the high potential of microcrystalline cellulose whereas the use of diatomaceous earth, acid-washed river sand and washed pith bagasse posed problems. The data indicate the potential of lactic acid production from sugar-cane pressmud in an SSF system.
Fermentation of L-(+)-lactic acid from soluble starch by Lactobacillus amylophilus was studied. The bacterium produced about 30 g of L-(+)-lactic acid from 50 g of soluble starch when the pH of the culture was ranging from pH 5 to pH 6.8 at 28C. 53.4 g of L-(+)-lactic acid was produced when 100 g of starch was added in the medium. The fermentation procedures will reduce the cost of complete hydrolysis of starch to glucose prior to fermentation.
Lactobacillus amylovorus utilized raw corn, rice and wheat starch medium to produce lactic acid with a productivity of 10.1, 7.9 and 7.8 g lactic acid/L, but had lower productivities of 4.8 g/L and 4.2 g/L on cassava and potato starch in basal medium respectively. When peptone (1%) is added to basal medium with cassava starch as substrate, conversion rate increased from 43% conversion to 70% conversion (7.7 g lactic acid/L). The availability of some components of protein in corn starch is assumed to be the reason for high lactic acid production as compared to that of cassava starch.
A kinetic model of the fermentative production of lactic acid from glucose by Lactococcus lactis ssp. lactis ATCC 19435 in whole-wheat flour has been developed. The model consists of terms for substrate and product inhibition as well
as for the influence of pH and temperature. Experimental data from fermentation experiments under different physical conditions
were used to fit and verify the model. Temperatures above 30 °C and pH levels below 6 enhanced the formation of by-products
and d-lactic acid. By-products were formed in the presence of maltose only, whereas d-lactic acid was formed independently of the presence of maltose although the amount formed was greater when maltose was present.
The lactic acid productivity was highest between 33 °C and 35 °C and at pH 6. In the concentration interval studied (up to
180 g l−1 glucose and 89 g l−1 lactic acid) simulations showed that both substances were inhibiting. Glucose inhibition was small compared with the inhibition
due to lactic acid.
The effect of different carbon sources on lactic acid production by Rhizopus oryzae was studied using glucose, sucrose, beet molasses, carob pod and wheat bran as substrate. The highest lactic acid concentration was obtained when 150 g/l glucose was present in the medium as the sole carbon source. In that case, the lactic acid yield was approximately 60% by weight based on the amount of glucose consumed. Wheat bran was found to be an unsuitable substrate for this particular fermentation. Pasteurisation of molasses increased lactic acid production rate compared to that of untreated molasses. Likewise, 58 g/l lactic acid was obtained by using the supernatant containing sugars extracted from carob pod. This medium could therefore be considered as an alternative carbon source for lactic acid production.
Wheat bran is an underexploited cheap byproduct obtained during the milling process of wheat. The ability of Lactobacillus amylophilus GV6 to hydrolyze raw starch in wheat bran to produce l(+) lactic acid was studied in solid state fermentation (SSF), opening a novel method for the utilization of these agricultural byproducts. l(+) Lactic acid production by L. amylophilus has been reported by various groups from processed and unprocessed starch but there are no reports available from natural starches in SSF. All amylolytic wild strains reported so far have high yield efficiencies at low substrate concentrations whereas at high substrate concentrations lactic acid production was low. L. amylophilus GV6 showed high yield efficiency at high substrate concentration in SSF. To improve and optimize l(+) lactic acid production by L. amylophilus GV6, response surface methodology (RSM) using central composite rotatable design was adopted in SSF. MINITAB-13 was used for planning the experiments, data analysis, contour diagrams and response optimizations. The optimum media composition was obtained as peptone, 0.9%; yeast extract, 0.88%; tri-ammonium citrate, 0.379%; NaH2PO4·2H2O, 0.769% and Tween-80, 0.30 ml. Under these conditions a maximum of 36 g of lactic acid was produced per 100 g of wheat bran having 54 g of starch. The organism showed 90% yield efficiency based on substrate consumed. Successful optimization of the selected ingredients, led to 100% increase in lactic acid production, i.e. from 18 to 36 g. Due to its high potentiality in conversion of starch to l(+) lactic acid, L. amylophilus GV6 can be exploited industrially for developing a novel technology using inexpensive renewable resources.
Lactic acid derived from lactose is a major by-product of energy production in lactic acid bacteria. The uptake of lactose by these organisms is mediated either by the lactose phosphoenolpyruvate-phosphotransferase system (lactose PEP-PTS), or by a lactose-proton symport system. The disaccharide is then converted to lactate with the concomitant production of ATP. In Lactococcus lactis the genes encoding the lactose PEP-PTS, phospho-β-galactosidase and the tagatose 6-phosphate pathway enzymes are plasmid encoded, while other genes required for lactate synthesis, including those of the Embden-Meyerhof pathway, are on the chromosome. We have compiled a current list of genes required for lactate synthesis in the lactic acid bacteria that have been cloned and characterized and discuss the present status of genetic research in this area. The analyses of the L. lactis lac operon have yielded one of the most detailed pictures of genetic regulation in this bacterium. The operon has been fully sequenced, the regulatory protein LacR which represses lac operon transcription has been purified and its properties determined, and the operon promoters and operators have been identified. Investigations of chromosomally encoded L. lactis genes have resulted in the identification and characterization of pfk, pyk, ldh, tpi and gap, which encode phosphofructokinase, pyruvate kinase, l-(+)-lactate dehydrogenase, triosephosphate isomerase and glyceraldehyde-3-phosphate dehydrogenase, respectively. All of these enzymes (except triosephosphate isomerase) are known from previous studies to be important in metabolite level regulation of the pathway, pfk, pyk and ldh are organized into a tricistronic operon (the las operon), while tpi and gap are in monocistronic units. The las operon is so far unique to L. lactis. A number of investigators have studied the effect of gene dosage on glycolytic flux in lactic acid bacteria and their results are reviewed. We have introduced multiple copies of pfk, pyk, Idh and the las operon into L. lactis and report the effect of the increase in gene dosage on enzyme levels and the rate of lactic acid production.