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Nutritional Yeast Biomass: Characterization and Application

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Abstract

ABSTRACT A number of pre-clinical and clinical studies indicate that nutritional yeasts as well as Saccharomyces boulardii are important products for prophylactic and/or therapeutic purposes. Nutritional yeasts are a rich source of amino acids, single cell proteins, several bioavailable minerals (e.g. chromium, selenium, zinc, iron, magnesium, cooper, manganese), and B vitamins. The properties of these non-infectious yeasts may be of particular importance for human and animal health. Amongst them, Saccharomyces cerevisiae is the best-known species used as a source of B vitamins and nutrients, especially chromium and selenium incorporated as organic compounds. Chromium is necessary for the maintenance of normal blood glucose levels, while selenium promotes a normal function of immune system. Another less-known species is Yarrowia lipolytica, which contributes to the production of a number of important nutritional elements, including bioavailable proteins, essential amino acids, minerals, organic acids, polyalcohols, carotenoids, aroma compounds, single cell oil, and microbial surfactants. Nutritional yeasts are beneficial for vegans, vegetarians, athletes, reconvalescents, as well as young people during the puberty period. Furthermore, some yeast species possess properties required for a microorganism to be considered as probiotic. One of them is S. boulardii, particularly recommended in antibiotic-associated diarrhoea and recurrent Clostridium difficile intestinal infections. Keywords: nutritional yeasts, Saccharomyces cerevisiae, Saccharomyces boulardii, Yarrowia lipolytica, probiotics

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... Y. lipolytica utilizing waste as a raw cassava (bioethanol industry by-product) reduces poisonous cyanide concentration to a safe level [18]. The yeast has relatively low nutritional requirements, showing very high growth potential, and its culture is independent of geographic and weather conditions and fresh water availability [6,[19][20][21]. Additionally, the use of yeast biomass enriched in protein containing plenty of value compounds or its metabolites is easier accepted by society than other microorganisms due to its usefulness, i.e., in the production of fermented products [20]. ...
... In the near future, the problem could be solved by the production of huge quantities of nutritional yeast biomass. At present, mainly S. cerevisiae biomass and extract are used for human nutrition but not commonly and in small numbers [19,46]. However, the first step to use the Y. lipolytica biomass as food has already been taken. ...
... Hence, 100 g of Y. lipolytica powder contains almost 100% of the recommended daily portion. Moreover, protein quantity in Y. lipolytica powder is comparable to that of S. cerevisiae biomass and is similar or even higher than in traditional sources such as meat and soybean and higher than milk protein [19,46,72]. Furthermore, the protein efficiency ratio standardized for casein (PER) of yeast protein is comparable with the PER of meat and soybean [72,108]. ...
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Yarrowia lipolytica, an oleagineous species of yeast, is a carrier of various important nutrients. The biomass of this yeast is an extensive source of protein, exogenous amino acids, bioavailable essenctial trace minerals, and lipid compounds as mainly unsaturated fatty acids. The biomass also contains B vitamins, including vitamin B12, and many other bioactive components. Therefore, Y. lipolytica biomass can be used in food supplements for humans as safe and nutritional additives for maintaining the homeostasis of the organism, including for vegans and vegetarians, athletes, people after recovery, and people at risk of B vitamin deficiencies.
... Therefore, the answer to humankind's challenge to meet the need of protein products seems to be the protein produced by various microorganisms such as bacteria, yeast, algae, and fungi. This microbial protein is also called bioprotein, protein biomass, or single cell protein (SCP), though filamentous algae and fungi may be multicellular [7,11]. SCP is dead and dried biomass of microorganisms which culture on various carbon and energy sources ( Figure 1). ...
... Obtaining microbial protein by conversion of waste substrates to value-added feed and food as high nutritional protein biomass and thus reduction of environmental pollutions is very important valuable feature of SPC production [14]. Particularly, yeast plays a special role in purifying the environment from waste materials, especially oleaginous yeast such as Yarrowia lipolytica and Candida spp. that are capable of growing on many industrial wastes including alkanes, petroleum by-products, natural gas, glycerol, biofuel waste, and plant or animal-waste fats [11,12,[15][16][17][18][19]. The oily waste biodegradation by this yeast has a significant importance for environmental protection [16,18,[20][21][22]. ...
... One of the methods of getting rid of oily waste products after processing petroleum is its use as a culture medium for the production of added value compounds, such as protein, by yeast that can utilize these wastes [18,24,25]. Furthermore, both food grade or industrial wastes as well as forestry and agricultural sources are easily available and low-or even free-cost substrates as carbon and energy sources for SCP production by yeast [7,11,17,18,[26][27][28][29]. On the market of some countries, currently, there are: some food spreads made of yeast extract, especially bakery or brewery Saccharomyces cerevisiae; food supplements containing brewery or bakery yeast or algae; a meat substitute product provided from filamentous fungus Fusarium venenatum and yeast Torula (Candida utilis, renamed as Pichia jadinii); Pichia and Kluyveromyces used as flavoring agent [7,30]. ...
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In recent years, the awareness and willingness of consumers to consume healthy food has grown significantly. In order to meet these needs, scientists are looking for innovative methods of food production, which is a source of easily digestible protein with a balanced amino acid composition. Yeast protein biomass (single cell protein, SPC) is a bioavailable product which is obtained when primarily using as a culture medium inexpensive various waste substrates including agricultural and industrial wastes. With the growing population, yeast protein seems to be an attractive alternative to traditional protein sources such as plants and meat. Moreover, yeast protein biomass also contains trace minerals and vitamins including B-group. Thus, using yeast in the production of protein provides both valuable nutrients and enhances purification of wastes. In conclusion, nutritional yeast protein biomass may be the best option for human and animal nutrition with a low environmental footprint. The rapidly evolving SCP production technology and discoveries from the world of biotechnology can make a huge difference in the future for the key improvement of hunger problems and the possibility of improving world food security. On the market of growing demand for cheap and environmentally clean SPC protein with practically unlimited scale of production, it may soon become one of the ingredients of our food. The review article presents the possibilities of protein production by yeast groups with the use of various substrates as well as the safety of yeast protein used as food.
... It has been shown that Y. lipolytica grown on a medium with different fatty wastes is a natural source of such nutritional components as single cell oils (especially mono-unsaturated fatty acids and saturated cocoa-butter equivalents), protein (i.e. single cell protein, SCP), amino acids, and B-group vitamins, including vitamin B12 (16, 17,18,19,20,21,22,24). In this respect, this yeast occupies an important place in pharmaceutical, feed, and food industry (20). ...
... single cell protein, SCP), amino acids, and B-group vitamins, including vitamin B12 (16, 17,18,19,20,21,22,24). In this respect, this yeast occupies an important place in pharmaceutical, feed, and food industry (20). ...
... Moreover, the use of this yeast biomass as an additional nutritional supplement can support a solution to the problem of food scarcity in the ever-growing human population, especially in developing countries such as India and Burkina Faso (20,28). In 2019, the European Food and Safety Authority (EFSA) authorized the use of dried and heat-killed Y. lipolytica biomass as a novel food in dietary supplements intended for the general population above 3 years of age [29]. ...
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Background Yarrowia lipolytica is an oleaginous yeast with the ability to grow in a variety of hydrophilic and hydrophobic substrates, including industrial wastes, in which it produces and accumulates various nutrients. Methods The aim of the present study was to examine the presence of free L-carnitine in the biomasses of two Yarrowia lipolytica strains (ATCC 9793 and A-101) growing in YPD medium and biofuel waste. The cultivations of Y. lipolytica were performed in aerobic conditions at different temperatures (20–30°C) and pH values (4.0–7.0) of the media with and without the addition of precursors for L-carnitine production, such us iron, trimethyllysine, and L-ascorbic acid in a laboratory scale or chromium chloride (III) in a pilot plant scale. Results Both tested Y. lipolytica strains grown in fatty acid-poor YPD medium at 20°C and pH 6.0 contained endogenous free L-carnitine in their biomass with a maximum of 22.85 mg/100 g of wet biomass. The addition of L-carnitine precursors to the YPD medium exerted a significant effect on L-carnitine concentration in the yeast biomass, increasing it up to 250%. In turn, the biomass of both tested Y. lipolytica strains cultivated in the biofuel waste, irrespective of the culture conditions, contained below 1 mg of L-carnitine/100 g of wet biomass. However, the supplementation of the culture media with the L-carnitine precursors significantly increased the yield of the yeast biomass by 20–30% in the biofuel waste cultures. Moreover, the addition of chromium(III) chloride into the biofuel waste caused an increase in the free L-carnitine concentration in the yeast biomass up to 2.24 mg/100 g of dry weight. Conclusion Biomass of Y. lipolytica grown in the free fat medium contained free L-carnitine, in contrast to the biomass grown in the fat-rich biofuel waste. The very low amounts of L-carnitine in the biomass of Y. lipolytica grown in the crude biofuel waste suggest that the yeast is able to utilize almost the entire pool of free L-carnitine for growth and nutritional biomass production. However, the addition of chromium to the biofuel waste contributed to an increase in L-carnitine concentration in Y. lipolytica biomass.
... Oleaginous yeast Yarrowia lipolytica is well-known for its ability to grow in a wide range of substrates, especially non-conventional hydrophobic ones, such as vegetable or animal-waste fats, different fractions of petroleum, or waste streams from various industries (Dourou et al., 2018;Groenewald et al., 2013;Jach et al., 2017;Jach and Serefko, 2018;Katre et al., 2012;Lopes et al., 2018Lopes et al., , 2019Papanikolaou et al., 2001Papanikolaou et al., , 2003RywiĔska et al., 2013). The fatty waste biodegradation by this yeast is very important for environmental protection in line with the take-make-dispose concept (Katre et al., 2012;Lopes et al., 2019;Saygün et al., 2014;Vasiliadou et al., 2018;Tzirita et al., 2018). ...
... One way to recycle fatty waste is its utilization as fermentation media component for the production of added value compounds by microorganisms like yeast (Lopez et al. 2019). Thus, the ability of Y. lipolytica to produce biomass rich in various nutritional components in available inexpensive oily wastes, as carbon sources, is highly beneficial for protecting the environment (Dobrowolski et al., 2007;Groenewald et al., 2013;Jach et al., 2017;Jach and Serefko, 2018;Katre et al., 2012;Lopes et al., 2018;5 lipids intracellularly up to 40% of its cell dry weight or produce 30-50% protein of dried biomass (Drzymaáa et al. 2020;Bellou et al., 2016;Beopoulos et al., 2011;Dourou et al., 2018;Jach et al., 2017;Juszczyk et al., 2013;Lopes et al., 2018Lopes et al., , 2019Papanikolaou et al., 2001Papanikolaou et al., , 2003RywiĔska et al., 2013). Similar to animal cells, Y. ...
... Hence, the U.S. FDA has granted the "Generally Regarded as Safe (GRAS)" status to several production processes using Y. lipolytica (Groenewald et al., 2013;Zieniuk and Fabiszewska, 2019). In this regard, dried and heat-killed nutritional yeast cells can be added as a cheap supplement to the regular human diet to help in solving the problem of food deficiency in rapidly growing populations, especially in developing countries like India (Jach et al., 2017;Jach and Serefko, 2018;Kennedy, 2015). Additionally, the nutritional yeast biomass is obtained very fast (in comparison with the growth of plants or animals), from a relatively small area and regardless of the weather. ...
Article
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Yarrowia lipolytica as an oleaginous yeast is capable of growing in various non-conventional hydrophobic substrate types, especially industrial wastes. In this study, the content of thiamine (vitamin B1), riboflavin (vitamin B2), pyridoxine (vitamin B6), biotin (vitamin B7) and folic acid (vitamin B9) in the wet biomass of Y. lipolytica strains cultivated in biofuel waste (SK medium), compared to the standard laboratory YPD medium, was assessed. Additionally, the biomass of Y. lipolytica A-101 grown in biofuel waste (SK medium) was dried and examined for B vitamins concentration according to the recommended microbial methods by AOAC Official Methods. The mean values of these vitamins per 100 g of dry weight of Y. lipolytica grown in biofuel waste (SK medium) were as follows: thiamine 1.3 mg/100 g, riboflavin 5.3 mg/100 g, pyridoxine 4.9 mg/100 g, biotin 20.0 µg/100 g, and folic acid 249 µg/100 g. We have demonstrated that the dried biomass is a good source of B vitamins which can be used as nutraceuticals to supplement human diet, especially for people at risk of B vitamin deficiencies in developed countries. Moreover, the biodegradation of biofuel waste by Y. lipolytica is desired for environmental protection.
... Studies reported elsewhere [5][6][7] revealed that yeast biomass, or so-called nutritional yeasts, can be a valuable addition for diet poor in animal products. Yeast like Saccharomyces cerevisiae and non-conventional species e.g. ...
... lysine and methionine, which occur in limited amounts in most plant and animal foods [5,6,[8][9][10][11]. The use of nutritional yeast biomass as a supplement to the regular diet can help solve the problem of food scarcity in ever-growing human population, especially in developing countries like India [6,7]. Now, Y. lipolytica is used as a high-quality protein source for livestock feeding, as a biotechnological production host for several substances like organic acids, PUFAs, carotenoids or enzymes as well as for bioremediation purposes [12]. ...
... A metabolic pathway B12 production is involved in ex novo accumulation of vitamin B12 (from substrates) in biomass produced by yeast. In contrast to de novo B12 synthesis by bacteria, ex novo B12 production is an anabolic process, occurring simultaneously with cell growth [13][14][15][16][17]. Being environmental friendly, Y. lipolytica utilizes inexpensive non-conventional feedstock and waste to produce biomass [6][7][8][9][10][11][12]. In this respect, yeast occupies an important place in pharmaceutical, feed, and food industry [7]. ...
Article
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The aim of the study was to obtain vitamin B12-enriched biomass of non-conventional yeast Yarrowia lipolytica A-101. The cultivations were performed on waste from biofuel production in aerobic conditions at different temperatures (20–30 °C) and pH values (4.0–7.0) of the medium, with and without the addition of cobalt, l-methionine, molybdenum, δ-aminolevulinic acid, and niacin. A temperature of 30 °C and pH between 5 and 6 were the optimal conditions for obtaining B12-enriched yeast biomass on biofuel waste. In such conditions, Y. lipolytica A-101 contained 9 µg of vitamin B12 per 100 g of dried biomass. The addition of the ingredients mentioned above to the medium did not exert a significant effect on the B12 concentration. Y. lipolytica are able to accumulate this vitamin from the medium in a similar manner to animal cells. Additionally, it should be noted that the dried biomass of Y. lipolytica appeared to be safe for consumption. Taken together, these data showed that Y. lipolytica can be used as a nutritional supplement to increase the intake of vitamin B12, especially at risk of vitamin B12 deficiency.
... An example of a cellular product that does not secrete its protein of interest is nutritional yeast that uses the cheesy flavor of inert S. cerevisiae. 58 Currently, some companies use recombinant bacteria strains to express casein proteins, which is simpler as a prokaryote cell. Collagen is currently used in processed foods such as sausages or beef patties, 59 and it can be used as a binder in the production of protein powders rather than carbohydrates since it does not affect the nutrition of the powder. ...
... 59 The form typically added to these food products is hydrolyzed collagen, which is produced from the enzymatic hydrolysis of collagen tissue. 60 It has been studied on its use with rice protein 55,58 and works through agglomerating the protein by promoting an increase in the particle size. This interaction between collagen and plant protein could make collagen a suitable binder for use in the production of PBMA. ...
... It is also possible to apply yeasts in fermentative processes for food generation. It has been applied in agriculture, production of biofuels, medicines, chemical industry, and even environmental protection (Jach and Serefko 2018;Fleet 2011). They are divided into two families: Ascomycota and Basidiomycota. ...
... To produce biomass, it is possible to use heterotrophic bacteria which can convert phosphorus and nitrogen from waste obtained from fish farming. This type of bacteria requires a C:N ratio between 12:15 for optimum biomass production (Jach and Serefko 2018). Few hydrogen oxidizing bacteria can obtain good yields in the production of unicellular protein. ...
Chapter
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Agro-industrial production generates large volumes of effluents with a high content of solids, nutrients, organic matter, and microorganisms. These effluents can negatively modify natural environments that receive them by surface runoff or infiltration through the soil, with possible damage to the population’s health. The objective of the circular economy is to maintain—as long as possible—the materials, products, and resources used in the production system to diminish, in this way, contaminating wastes. The “biologization” of industrial processes using the purification capacity of microalgae to decontaminate wastewaters has emerged in recent years. It offers two benefits, the production of biomass for different uses and the production of cleaner effluents. After microalgal treatments, ecotoxicity tests are used to assess the effectiveness of decontamination processes. In addition, bioassays indicate how long it is necessary to continue the decontamination process, i.e., when the concentration with no toxic effects has been reached, thus reducing unnecessary costs.
... The nutrient content of nutritional yeast includes carbohydrates, protein, fat, vitamins and minerals. Nutritional yeast also contains several nutrients that are not found in other vegetable sources, that is lysine and methionine and several vitamins (Jach & Serefko, 2018). Nutritional yeast has a taste similar to cheese, which is salty and savory. ...
Article
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Vegan are group of people who have high risk of megaloblastic anaemia because of vitamin B12 and folic acid defi ciency. Purple sweet potato (Ipomoea Batatas L.) and nutritional yeast are rich vitamin B12 and folic acid, therefore can be formulated into healthy food, such as snack bar for vegan. The purpose of this study is to determine the eff ect of purple sweet potato substitution and nutritional yeast addition on acceptability and availability of vitamin B12 and folic acid of snack bar. The type of research of formulation was true experimental design (Complete Randomize Design) with 1 formula control and 2 modifi ed formula. This research was carried out for 3 months (December 2018-March 2019) in Nutrition Laboratory Universitas Airlangga. The panelists are 38 people who affi liated with vegan community Yayasan Buddha Maitreya Surabaya. Statistical analysis used Kruskall Wallis test and Mann Whitney test with 5% signifi cance level. The results of organoleptic test showed that the most preferred formula by panelists was F2 with an average value of 3,6. There are diff erences in terms of smell characteristic (p=0.017) and taste characterictic (p=0.021). F2 have the highest content of vitamin B12 and folic acid, which are 1.58 mcg and 1,62 mcg, respectively, for 50 gram snack bar. The study showed that the best optimization (acceptability and nutrient content) in formula is F2 (substitution of 20% of purple sweet potato and addition 9 g of nutritional yeast). Therefore, snack bar with purple sweet potato substitution and nutritional yeast enrichment is feasible as an alternative healthy snack for vegan.
... The use of yeast cell components for microencapsulation is a recent and relevant facet of yeast prospecting. The use of yeasts as an encapsulating agent satisfies the requirements for wrapping, incorporating, storing, protecting and releasing, in addition to being considered a matrix with high nutritional value and low cost, highlighting its use compared to other encapsulating agents (Dadkhodazade et al., 2018;Jach and Serefko, 2018). Besides, ascospores have resistance to extreme conditions such as digestive enzymes, heat, and organic solvents (Rao et al., 2019). ...
Article
In this study, yeasts were isolated from an indigenous starter culture for cachaça production (Brazilian spirit) and brewer’s spent grain and characterized through a series of phenotypic assays: the killer profile, ascospore formation capacity, growth at high temperatures, resistance to natamycin and actidione, and exoenzyme production. One hundred thirty-four (n = 134) yeasts were isolated and identified as belonging to 6 genera and 10 different species. The ascospore formation in potassium acetate agar was observed in 86% of the isolates (73 Saccharomyces cerevisiae, 3 Torulaspora delbrueckii, and 1 Wickerhamomyces anomalus) highlighting their potential for microencapsulation. Only S. cerevisiae LMQA SNR 70 expressed an effective killer factor (ability to destroy sensitive strains), while only 3 S. cerevisiae, 1 Clavispora lusitaniae, and 1 Pichia kudriavzevii isolates were able to grow up at 45 °C. At 50 and 100 mg/L, actidione showed selectivity action for Candida parapsilosis, while natamycin inhibited the growth of all isolates. The non-Saccharomyces isolates stood out in the qualitative and quantitative tests for amylolytic, pectinolytic, cellulolytic, and xylanolytic activities. A predominance of the species W. anomalus and T. delbrueckii was observed. Besides, quantitative tests revealed that 23% of the isolates exhibited exoenzymatic activity in a nutrient-poor environment, and W. anomalus LMQA CSC 5 e LMQA CSC 43 stood out for the multi-enzymatic in agar and liquid medium response. The phenotypic profile showed that 16% of the isolates expressed two or more characteristics studied, with 2/3 represented by the non-Saccharomyces species. These results highlight the importance of studying yeast species for new biotechnological purposes.
... As nutritional yeasts are gluten free, they are suitable source of food for the celiac population (USDA, 2014;Pérez-Torrado et al., 2015). Therefore, the consumption of food products enriched with nutritional yeast, such as ready-to-eat snacks developed from pulses flours, is a healthy alternative for celiac people, vegans, athletes, as well as young people during the puberty period (Jach & Serefko, 2018). ...
Article
The food industry is increasingly innovating and applying new processing technologies and ingredients to develop novel food products that meet the consumers' demand. In this study, the effect of extrusion (at 140 °C and 160 °C) was evaluated in different lentil flours formulations enriched with nutritional yeast, in terms of α-galactosides (raffinose, stachyose, verbascose), inositol phosphates (IPs), trypsin inhibitors and lectins content. The content of α-galactosides and IPs was determined by high performance liquid chromatography. Trypsin inhibitor activity (TIA) was evaluated using a small-scale quantitative assay. The lectin content was analyzed using a haemagglutination assay and a Competitive Indirect Enzyme-linked immunosorbent assay. Extrusion promoted a significant increase, up to 85% in total α-galactosides content. After extrusion, IPs content was significantly decreased and TIA as well as lectins content had a reduction higher than 90%. Extrusion demonstrated to have a beneficial effect by increasing desirable prebiotic compounds and decreasing non-nutritional factors.
Article
Many gluten-free foods are prepared from starch-rich ingredients with low protein and fiber content, resulting in poor nutritional and functional quality. In this study, five different composite legume flours which are prepared from different levels of chickpea, lentil, common bean, soybean and lupin flours were used at 75% level in gluten-free tarhana formulations to improve nutritional quality. Also, effect of baker’s yeast (Saccharomyces cerevisiae) at different levels (2.5% and 5.0%) on physicochemical and sensory attributes of the samples containing composite flours was investigated. The inclusion of composite flours (75%) resulted in lower L* and hue values in tarhana than gluten-free sample without composite flour. The viscosity of tarhana containing “25% chickpea+50% lentil” composite flour (F2) was similar to traditional wheat tarhana (p > 0.05). The utilization of composite flours containing “50% chickpea+25% lentil” (F1), F2, and “25% chickpea+25% lentil+25% common bean” (F3) in tarhana revealed comparable oil absorption capacity to wheat tarhana. Besides, pH and foaming capacity values of samples containing composite flours were greater than wheat tarhana and gluten-free tarhana without composite flour. The addition of composite flours elicited markedly higher ash, protein, fat, and mineral content. While phytic acid concentration of tarhana enhanced with the incorporation of composite flour, the use of 5.0% yeast considerably decreased phytic acid content and enriched ash, protein, total phenolic content, Ca, Cu, K, Mg, and P concentrations of tarhana in comparison with tarhana containing 2.5% yeast. The inclusion of F1, F2, and F3 elicited acceptable sensory scores in tarhana. It was concluded that gluten-free tarhana prepared from legume composite flours (especially F1, F2, and F3) + 5.0% yeast could offer a nutritious and acceptable alternative for gluten-free diet with greater protein and mineral contents. Based on the findings, further studies may evaluate the use of hydrocolloids to improve the technological and sensory properties of functional tarhana formulations developed in this study.
Chapter
Humanity has been used microbial biomass for food production and now; for biofuels, drugs, and other useful compounds. Different microorganisms are employed in the production of biomass ranging from bacteria, yeast, fungi, and algae which are used to produce food, bioactive compounds, enzymes, hydrolysates, among others. Due to the accelerated population growth in the world and the need to meet its nutritional requirements, the search for alternatives that help to solve this social problem is one of the most pressing tasks.
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Abstract Yarrowia lipolytica is an oleaginous yeast species with the ability to grow on a number of substrates types, especially industrial wastes. This paper concerns the statistical optimization of fermentation parameters and media to ensure consistent and improved Y. lipolytica protein production. A strain of Y. lipolytica A-101 was observed to be proficient in producing single cell protein, amino acids, and vitamin B12 while utilizing biofuel waste instead of a complete YPD medium for yeast growth. A fractional fractal design experiment was then applied, and the two fermentation parameters of temperature and pH were recognized to have a significant effect on the protein and amino acid production. Subsequently, the response surface methodology with a three-level complete factorial design was employed to optimize these influential parameters. Therefore, five different measuring systems were utilized to construct a quadratic model and a second-order polynomial equation. Optimal levels of parameters were then obtained by analysis of the model and the numerical optimization method. When the Y. lipolytica A-101 was cultivated at optimized pH (5.0) using biofuel waste as a medium, the protein concentration was increased to 8.28—a 44% enhancement as compared to the original (3.65). This study has thus demonstrated a beneficial way to cultivate Y. lipolytica A-101 on biofuel waste for enhanced production of single cell protein and amino acids for use in human diet and in animal feed.
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Aims Chromium (Cr) is a trace element involved in glucose homeostasis. We aim to evaluate and quantify the effects of Cr supplementation on A1C and FPG in patients with T2DM. Materials and methods A systematic literature search of Pubmed, EMBASE and the Cochrane Library (from database inception to 11/2014) with no language restrictions sought RCTs or cohort studies evaluating Cr supplementation in T2DM vs control and reporting either change in glycated hemoglobin (A1C) or fasting plasma glucose (FPG). Meta-analysis was conducted on each subtype of Cr supplement separately, and was analyzed by random effects model to yield the weighted mean differences (WMD) and 95% confidence intervals (CIs). Heterogeneity was assessed by using the I2 statistic. Results A total of 14 RCTs (n = 875 participants, mean age range: 30 to 83 years old, 8 to 24 weeks of follow-up) were identified (Cr chloride: n = 3 study, Cr picolinate: n = 5 study, brewer’s yeast: n = 4 study and Cr yeast: n = 3 study). Compared with placebo, Cr yeast, brewer’s yeast and Cr picolinate did not show statistically significant effects on A1C. Furthermore, compared to control, Cr chloride, Cr yeast and Cr picolinate showed no effect on FPG, however, brewer’s yeast showed a statistically significant decrease in FPG -19.23 mg/dL (95% CI = -35.30 to -3.16, I2 = 21%, n = 137). Conclusions Cr supplementation with brewer’s yeast may provide marginal benefits in lowering FPG in patients with T2DM compared to placebo however it did not have any effect on A1C.
Article
Brewer's yeasts are rich in vitamins of the B-group and contain other nutritive factors; therefore, they are recommended as valuable food supplements for people with special dietary requirements like pregnant women, children, and adolescents, or for people with high physical activity. Additionally, certain strains of brewer's yeast are known to be capable of adsorbing xenobiotics such as mycotoxins. Because of that, these yeasts are regarded as having positive effects in food, beverage, and feed technology. Their potential to bind mycotoxins such as ochratoxin A (OTA), however, can subsequently lead to a contamination of such brewer's yeasts used as food supplements. In the present study, we analyzed 46 samples of brewer's yeasts for the occurrence of OTA by HPLC with fluorescence detector (HPLC-FLD) and for confirmatory measurements by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Nearly 90 % of the samples were contaminated with OTA, the levels ranging from the limit of detection (LOD, 0.01 μg/kg) to 4.2 μg/kg. The mean and median levels of contamination were 0.49 and 0.27 μg/kg, respectively. Based on these results, the additional weekly OTA exposure by regularly consuming such supplements was assessed. Depending on different subpopulations (adults, children) and levels of contamination used for calculation, the additional OTA intake via brewer's yeast products ranged from 9.3 % (mean case) to 114 % (worst case) of the published mean weekly OTA intake in Germany (adults 279.3 ng, children 195.3 ng). At present, maximum levels for OTA in nutritional supplements like brewer's yeast do not exist. Based on our results, however, it is recommended that producers of these dietary supplements should include mycotoxin analyses in ongoing and future self-monitoring programs and in product quality checks.
Article
The oleaginous yeast Yarrowia lipolytica has become a recognized system for expression/secretion of heterologous proteins. This non-conventional yeast is currently being developed as a workhorse for biotechnology by several research groups throughout the world, especially for single-cell oil production, whole cell bioconversion and upgrading of industrial wastes. This mini-review presents established tools for protein expression in Y. lipolytica and highlights novel developments in the areas of promoter design, surface display, and host strain or metabolic pathway engineering. An overview of the industrial and commercial biotechnological applications of Y. lipolytica is also presented.