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Fermentation Strategies for PHB Production in a Novel Membrane Bioreactor: Investigating Batch and Fed-Batch Operations
Fungi and their natural products, like secondary metabolites, have gained a huge demand in
the last decade due to their increasing applications in healthcare, environmental cleanup, and
biotechnology-based industries. The fungi produce these secondary metabolites WSMs) during
the different phases of their growth, which are categorized into terpenoids, alkaloids,
polyketides, and non-ribosomal peptides. These SMs exhibit significant biological activity,
which contributes to the formulation of novel pharmaceuticals, biopesticides, and
environmental bioremediation agents. Nowadays, these fungal-derived SMs are widely used in
food and beverages, for fermentation, preservatives, protein sources, and in dairy industries.
In healthcare, it is being used as an antimicrobial, anticancer, anti-inflammatory, and
immunosuppressive drug. The usage of modern tools of biotechnology can achieve an
increase in demand for these SMs and large-scale production. The present review
comprehensively analyses the diversity of fungal SMs along with their emerging applications
in healthcare, agriculture, environmental sustainability, and nutraceuticals. Here, the authors
have reviewed the recent advancements in genetic engineering, metabolic pathway
manipulation, and synthetic biology to improve the production and yield of these SMs.
Advancement in fermentation techniques, bioprocessing, and co-cultivation approaches for
large-scale production of SMs. Investigators further highlighted the importance of omics
technologies in understanding the regulation and biosynthesis of SMs, which offers an
understanding of novel applications in drug discovery and sustainable agriculture. Finally, the
authors have addressed the potential for genetic manipulation and biotechnological
innovations for further exploitation of fungal SMs for commercial and environmental benefits.
Aerobic, hydrogen oxidizing bacteria are capable of efficient, non-phototrophic CO2 assimilation, using H2 as a reducing agent. The presence of explosive gas mixtures requires strict safety measures for bioreactor and process design. Here, we report a simplified, reproducible, and safe cultivation method to produce Cupriavidus necator H16 on a gram scale. Conditions for long-term strain maintenance and mineral media composition were optimized. Cultivations on the gaseous substrates H2, O2, and CO2 were accomplished in an explosion-proof bioreactor situated in a strong, grounded fume hood. Cells grew under O2 control and H2 and CO2 excess. The starting gas mixture was H2:CO2:O2 in a ratio of 85:10:2 (partial pressure of O2 0.02 atm). Dissolved oxygen was measured online and was kept below 1.6 mg/L by a stepwise increase of the O2 supply. Use of gas compositions within the explosion limits of oxyhydrogen facilitated production of 13.1 ± 0.4 g/L total biomass (gram cell dry mass) with a content of 79 ± 2% poly-(R)-3-hydroxybutyrate in a simple cultivation set-up with dissolved oxygen as the single controlled parameter. Approximately 98% of the obtained PHB was formed from CO2.
The utilization of waste cooking oil (WCO) or waste fish oil (WFO) as inexpensive carbon substrate for the production of poly(3-hydroxybutyrate) (PHB) by Cupriavidus necator H16 was investigated. Fed-batch cultivation mode in bioreactor was applied in this study. High cell dry weight (CDW) of 135.1 g/L, PHB content of 76.9 wt%, PHB productivity of 1.73 g/L/h, and PHB yield of 0.8 g/g were obtained from WCO. In the case of WFO, the CDW, PHB content, PHB productivity, and PHB yield were 114.8 g/L, 72.5 wt%, 1.73 g/L/h, and 0.92 g/g, respectively. The PHB productivity and yield obtained in the current study from WCO or WFO are among the highest reported so far for PHA production using oils as sole carbon substrate, suggesting that both WCO and WFO can be used as inexpensive carbon substrates for the production of PHA on an industrial scale.
Over the past decade, formic acid and acetic acid have gained increasing attention as alternative feedstocks for poly-3-hydroxybutyrate (PHB) production as these potentially CO2-derived molecules are naturally assimilated by Cupriavidus necator. Both organic acids were individually evaluated in fed-batch fermentations at bioreactor scale. Acetic acid was revealed as the most promising carbon source yielding 42.3 g L⁻¹ PHB, whereas no significant amount of PHB was produced from formic acid. Hence, acetic acid was further used as the substrate during process intensification. Key performance characteristics, including process stability, PHB titer, and productivity were optimized by introducing NH4-acetate as the nitrogen source, extending the growth phase, and implementing a repeated fed-batch procedure, respectively. These advanced fermentation strategies resulted in the establishment of a stable fermentation process reaching 58.5 g L⁻¹ PHB, while doubling the productivity to 0.93 g L⁻¹ h⁻¹ PHB.
Syngas fermentation to biofuels and chemicals is an emerging technology in the biobased economy. Mass transfer is usually limiting the syngas fermentation rate, due to the low aqueous solubilities of the gaseous substrates. Membrane bioreactors, as efficient gas–liquid contactors, are a promising configuration for overcoming this gas-to-liquid mass transfer limitation, so that sufficient productivity can be achieved. We summarize the published performances of these reactors. Moreover, we highlight numerous parameters settings that need to be used for the enhancement of membrane bioreactor performance. To facilitate this enhancement, we relate mass transfer and other performance indicators to the type of membrane material, module, and flow configuration. Hollow fiber modules with dense or asymmetric membranes on which biofilm might form seem suitable. A model-based approach is advocated to optimize their performance.
Production of medium chain-length poly(3-hydroxyalkanoates) [PHA] polymers with tightly defined compositions is an important area of research to expand the application and improve the properties of these promising biobased and biodegradable materials. PHA polymers with homopolymeric or defined compositions exhibit attractive material properties such as increased flexibility and elasticity relative to poly(3-hydroxybutyrate) [PHB]; however, these polymers are difficult to biosynthesize in native PHA-producing organisms, and there is a paucity of research toward developing high-density cultivation methods while retaining compositional control. In this study, we developed and optimized a fed-batch fermentation process in a stirred tank reactor, beginning with the biosynthesis of poly(3-hydroxydecanoate) [PHD] from decanoic acid by β-oxidation deficient recombinant Escherichia coli LSBJ using glucose as a co-substrate solely for growth. Bacteria were cultured in two stages, a biomass accumulation stage (37°C, pH 7.0) with glucose as the primary carbon source and a PHA biosynthesis stage (30°C, pH 8.0) with co-feeding of glucose and a fatty acid. Through iterative optimizations of semi-defined media composition and glucose feed rate, 6.0 g of decanoic acid was converted to PHD with an 87.5% molar yield (4.54 g L–1). Stepwise increases in the amount of decanoic acid fed during the fermentation correlated with an increase in PHD, resulting in a final decanoic acid feed of 25 g converted to PHD at a yield of 89.4% (20.1 g L–1, 0.42 g L–1 h–1), at which point foaming became uncontrollable. Hexanoic acid, octanoic acid, 10-undecenoic acid, and 10-bromodecanoic acid were all individually supplemented at 20 g each and successfully polymerized with yields ranging from 66.8 to 99.0% (9.24 to 18.2 g L–1). Using this bioreactor strategy, co-fatty acid feeds of octanoic acid/decanoic acid and octanoic acid/10-azidodecanoic acid (8:2 mol ratio each) resulted in the production of their respective copolymers at nearly the same ratio and at high yield, demonstrating that these methods can be used to control PHA copolymer composition.
Poly(3-hydroxybutyrate) (PHB) belongs to the family of polyhydroxyalkanoates, biopolymers used for agricultural, industrial, or even medical applications. However, scaling up the production is still an issue due to the myriad of parameters involved in the fermentation processes. The present work seeks, firstly, to scale up poly(3-hydroxybutyrate) (PHB) production by wild type C. necator ATCC 17697 from shaken flasks to a stirred-tank bioreactor with the optimized media and fructose as carbon source. The second purpose is to improve the production of PHB by applying both the batch and fed-batch fermentation strategies in comparison with previous works of wild type C. necator with fructose. Furthermore, thinking of biomedical applications, physicochemical, and cytotoxicity analyses of the produced biopolymer, are presented.
Fed-batch fermentation with an exponential feeding strategy enabled us to achieve the highest values of PHB concentration and productivity, 25.7 g/l and 0.43 g/(l h), respectively. The PHB productivity was 3.3 and 7.2 times higher than the one in batch strategy and shaken flask cultures, respectively. DSC, FTIR, ¹H, and ¹³C NMR analysis led to determine that the biopolymer produced by C. necator ATCC 17697 has a molecular structure and characteristics in agreement with the commercial PHB. Additionally, the biopolymer does not induce cytotoxic effects on the NIH/3T3 cell culture.
Due to the improved fermentation strategies, PHB concentration resulted in 40 % higher of the already reported one for wild type C. necator using other fed-batch modes and fructose as a carbon source. Thus the produced PHB could be attractive for biomedical applications, which generate a rising interest in polyhydroxyalkanoates during recent years.
Even though extensive research has been directed toward optimization of the strain, media, and the process, yet there is limited knowledge on the performance and viability of large-scale PHB production lines exploiting cyanobacteria. In this study, the scale-up challenges associated with photosynthetic PHB production are listed. The high PHB producing cyanobacterial mutant, MT_a24, a randomly mutated strain of Synechocystis sp. PCC 6714, has been tested in pilot-scale trials for photosynthetic PHB production under non-sterile conditions. The MT_a24 obtained PHB content of 0.356 g L⁻¹ and 1.7 g L⁻¹ of glycogen from CO2 after 10 days of cultivation using a self-limiting media and non-optimized cultivation parameters. The results obtained here suggest that in order to achieve high PHB productivity values of the lab and to overcome the existing scalability issues reassessment of the optimized parameters needs to be performed during the pilot-scale trials.
One of the main energy consumptions in wastewater treatment plants (WWTPs) is due to the oxygenation of aerobic biological processes. In order to approach to an energy self-sufficient scenario in WWTPs, Membrane Aerated Biofilm Reactors (MABRs) provide a good opportunity to reduce the impact of aeration on the global energy balance. However, mass transfer limitations derived from poor flow distribution must be tackled to take advantage of this technology. In this work, in order to improve mass transfer between biofilm and bulk water, a specific configuration was developed and studied at laboratory scale, aimed at compactness, energy efficiency and high nitrification rates. Nitrification rates were higher in the innovative configuration than in the conventional one, achieving a Volumetric Nitrification Rate (VNR) as high as 575.84 g NH4-N m⁻³ d⁻¹, which is comparable with confirmed technologies. Regarding energy consumption due to aeration, a reduction of 83.7% was reached in comparison with aeration through diffusers with the same Oxygen Transfer Efficiency (OTE). These results highlight the importance of hydrodynamic conditions and the membranes configuration on treatment performance.
The biosynthesis of poly(3-hydroxybutyrate) (PHB) directly from carbon dioxide (CO2), is a sustainable alternative for non-renewable, petroleum-based polymer production. The conversion of CO2 implies a reduction of greenhouse gas emissions. Hydrogen oxidizing bacteria such as Cupriavidus necator have the ability to store PHB using CO2 as a carbon source, i.e., through an autotrophic conversion. In this study, a mathematical model based on mass balances was set up to describe autotrophic PHB production. The model takes into account the stoichiometry and kinetics of biomass growth and PHB formation as well as physical transfer from the gas phase to the liquid fermentation broth. The developed model was calibrated and validated based on independent experimental datasets from literature, obtained for C. necator. The obtained simulation results accurately described the dynamics of autotrophic biomass growth and PHB production. The effect of oxygen (O2) and/or nitrogen stress conditions, as well as of the gas mixture composition in terms of O2 and hydrogen (H2) was investigated through scenario analysis. As major outcome, a higher maximum PHB concentration was obtained under oxygen stress conditions compared to nitrogen stress conditions. At high O2 fractions in the gas mixture, which would result in H2 limitation before O2 limitation, PHB production can be increased by applying nitrogen stress. The effect of the reactor type was assessed through comparing a continuous stirred tank reactor (CSTR) with an air-lift fermentor. The developed model forms the basis for future design with minimum experimentation of suitable control strategy aiming at a high PHB production.
Formic acid, acting as both carbon and energy source, is a safe alternative to a carbon dioxide, hydrogen and dioxygen mix for studying the conversion of carbon through the Calvin–Benson–Bassham (CBB) cycle into value-added chemical compounds by non-photosynthetic microorganisms. In this work, organoautotrophic growth of Ralstonia eutropha on formic acid was studied using an approach combining stoichiometric modeling and controlled cultures in bioreactors. A strain deleted of its polyhydroxyalkanoate production pathway was used in order to carry out a physiological characterization. The maximal growth yield was determined at 0.16 Cmole Cmole−1 in a formate-limited continuous culture. The measured yield corresponded to 76% to 85% of the theoretical yield (later confirmed in pH-controlled fed-batch cultures). The stoichiometric study highlighted the imbalance between carbon and energy provided by formic acid and explained the low growth yields measured. Fed-batch cultures were also used to determine the maximum specific growth rate (μmax = 0.18 h−1) and to study the impact of increasing formic acid concentrations on growth yields. High formic acid sensitivity was found in R eutropha since a linear decrease in the biomass yield with increasing residual formic acid concentrations was observed between 0 and 1.5 g l−1.
The effect on intra-membrane oxygen pressure at a constant carbon substrate loading rate on the development of biofilms of Vibrio natrigens in a membrane aerated biofilm reactor (MABR) was investigated experimentally and by mathematical modelling. A recently reported technique (Zhang et al., 1998. Biotechnol. Bioeng. 59: 80-89) for the in situ measurement of the substrate diffusion coefficients in a growing biofilm and the mass transfer coefficients in the boundary layer at the biofilm liquid interface was used. This aided the study of the effect of the heterogeneous biofilm structure and also improved the reliability of the model predictions. The different intra-membrane oxygen pressures used, 12.5, 25 and 50 kPa, with acetate as the carbon substrate, showed a marked effect on the initial biofilm growth rate, on acetate removal rate, particularly in thick biofilms and on biofilm structure. The model predicted the substrate limitation regimes, the location of the active biomass layer within the biofilms and the trends in oxygen uptake rate through the membrane into the biofilms. During the development of the biofilms, the biofilm thickness and the intra-membrane oxygen pressure were found to be the most important parameters influencing the MABR performance while the effect of biofilm structure was less marked.
Free sugars from fruit wastes were evaluated for the production of poly(3-hydroxybutyrate) (PHB) in Paraburkholderia sacchari fed-batch bioreactor fermentations. Different initial sugar concentration, carbon to inorganic phosphorus (C/IP) ratio, IP addition during feeding and volumetric oxygen transfer coefficient (kLa) were evaluated to promote PHB production. The highest intracellular PHB accumulation (66.6%), PHB concentration (108.3 g/L), productivity (3.28 g/L/h) and yield (0.33 g/g) were achieved at 40 g/L initial sugars, C/IP 26.5, 202.6 h-1kLa value and 20% IP supplementation in the feeding solution. The effect of different cell's harvesting time on PHB properties showed no influence in weight average molecular weight and thermal properties. The harvest time influenced the tensile strength that was reduced from 28.7 MPa at 22 h to 13.3 MPa at 36 h. The elongation at break and Young's modulus were in the range 3.6-14.8% and 830-2000 MPa, respectively.
The high costs of bioplastics' production may hinder their commercialization. Development of new processes with high yields and in biorefineries can enhance diffusion of these materials. This work evaluated the production of polyhydroxybutyrate (PHB) from the combination of milled corn starchy fraction hydrolysate and crude glycerol as substrates by the strain Cupriavidus necator LPB 1421. After optimization steps, maximum accumulation of 62% of PHB was obtained, which represents 11.64 g.L-1 and productivity of 0.162 g.Lh-1. In a stirred tank bioreactor system with 8 liters of operational volume, 70% of PHB accumulation was reported, representing 14.17 g.L-1 of the biopolymer with 0.197 g.Lh-1 productivity. PHB recovery was conducted using a chemical digestion method, reaching >99% purity. Therefore, the potential application of milled corn as substrate for PHB production was confirmed. The developed bioplastic process could be coupled to a bioethanol producing unit creating the opportunity of a sustainable and economic biorefinery.
Cupriavidus necator owes its popularity to the ability to produce large amounts of the polyester poly (3-hydroxybutyric acid), or PHB. During the last decades, C. necator has earnt an increasing interest in the field of biopolymers and bioplastic production. This versatile bacterium can grow both autotrophically on a mixture of gases (e.g. hydrogen, oxygen, and carbon dioxide) and heterotrophically, on a wide range of organic substrates, including waste feedstocks. In anoxic conditions, it can also denitrification by using nitrate as the electron acceptor.
The goal of this review is to underline the versatility of C. necator and its ability to produce biopolymers on a wide variety of carbon sources, comparing pure and waste substrates, used in circular economy biobased PHA production. This study analysis highlight the most suitable feeding strategies to reach the highest PHB accumulation, underlying the important role that C. necator could play for next generation biopolymers.
Microbial protein is proposed as an alternative protein source with low environmental impact. Methane oxidizing bacteria are already produced at commercial scale from natural gas. However, their productivity is limited because of the creation of explosive atmospheres in the fermenters during production. This work demonstrates the applicability of bioreactors with a membrane-based gas supply via diffusion. Methanotrophic bacteria were successfully cultivated, with growth yields from 0.26 to 0.43 g-VSS g-CH4⁻¹, slightly below those observed in analogous fermenters relying on bubbling. However, ammonia yields ranged from 5.2 to 6.9 g-VSS g-NH3⁻¹, indicating higher nitrogen assimilation than in conventional fermenters. Indeed, protein content increased during the operational period reaching up to 51% of dry weight. The amino acid profile included the majority of the essential amino acids, demonstrating suitability as feed ingredient. Never during the operational period was an explosive atmosphere established in the reactor. Thus, bubble-free membrane bioreactors are a promising technology for microbial protein production relying on explosive gas mixtures.
In this study, poly(3-hydroxybutyrate) (PHB) production was investigated for the first time using high cell density cultivation of Methylocystis hirsuta from natural gas. Various carbon sources including acetate, ethanol and glucose were used in a loop bioreactor. Then, effects of magnesium and phosphorus contents on PHB production were investigated. Results revealed that the bacterial strain had the capability to grow on various substrates. Furthermore, the cell dry mass (CDM) reached to 4.5 g/L with a PHB content of 85% (w/w) using a ratio of 1:1 of methanol:ethanol. Deficiencies of magnesium and phosphorus were shown to play a key role to achieve high cell densities in bioreactors. In addition, PHB was produced in a bubble column bioreactor at optimum conditions, resulting in the production of 8 g/L of CDM with a PHB content of 73.4% (w/w).
Current gas/liquid membrane contactors are classified into tubular hollow fiber contactors and tube-shell cross flow hollow fiber contactors. They are usually built with a closed and integrated structure, which reduces the maintainability of the contactor and makes the scaling-up of the contactor inconvenient. In this paper, a novel gas/liquid hollow fiber membrane contactor is proposed. It is consisted of many changeable and standard small contactors (elements), in which the fibers are randomly packed. These randomly packed small elements are then serially and orderly arranged to form the scaled up contactor for industrial applications. A two-dimensional predictive model is proposed to study the performance of the contactor, which is validated by air humidification experiments. The effects of inter-elements and intra-element flow maldistributions are investigated. Correlations are proposed to estimate the performance of the contactor from the parameters of the elements. It is found that for the contactors built with elements of high packing densities (0.5), the inter-elements effect is dominant for flow maldistribution, but for contactors built with elements of low packing densities (0.35), the collaborative effect of inter-elements and intra-element is dominant. It could maximally decrease the average air side Sherwood numbers by about 83%, with a pressure drop reduction of about 50%. The scaled up contactor has a comparable performance to the small elements when the elements are optimized, which shows the good scalability of this novel contactor.
Implementation of biofuels as an alternative to fossil fuels has been established as an answer to climate change by limiting GHG emissions. Syngas fermentation has emerged as a promising process for the conversion of waste biomasses to valuable products with bioethanol being on the main focus. However, the bottleneck of the mass transfer of syngas compounds H2 and CO along with low production yields has set barriers to the development of an industrial scale plant. Recent research indicates that many different methodologies spring up in order to face this important challenge. The aim of this review is to assemble all these techniques applied in syngas fermentation, focusing on the different bioreactor configurations operated in continuous mode for the production of liquid and gas biofuels. This article also outlines the so far entrepreneurial initiatives and the progress made towards the commercialization of the process.
The membrane-biofilm reactor (MBfR), sometimes known as the membrane-aerated biofilm reactor (MABR), is an emerging treatment technology based on gas-transferring membranes. The membranes typically supply a gaseous electron donor or acceptor substrate, such as oxygen, hydrogen, and methane. The substrate diffuses through the membrane to a biofilm naturally forming on the membrane outer surface. The complementary substrate (electron donor or acceptor) typically diffuses from the bulk liquid into the biofilm, making MBfR counter diffusional. This paper reviews the unique behavior of counter-diffusional biofilms and highlights recent research on the MBfR. Key advances include insights into the microbial community structure of MBfRs, applying the MBfR to novel contaminants, providing a better understanding of biofilm morphology and its effects on MBfR behavior, and the development of methane-based MBfR applications. These advances are likely to further the development of the MBfR for environmental applications, such as energy-efficient wastewater treatment and advanced water treatment.
Biosynthesis of poly-3-hydroxybutyrate (PHB) by Methylocystis hirsuta from natural gas in two different media was studied for the first time. After selection of the suitable medium, the effect of two key parameters such as methane to air ratio and nitrogen content on the PHB production was determined in a bubble column bioreactor using a full factorial design. It was found that both of these factors had a significant effect on the PHB accumulation (42.5% w/w of cell dry weight). PHB production by M. hirsuta, unlike other methanotrophic bacteria, was found to be a growth associated metabolite. Subsequently, the PHB production was carried out in a forced-liquid vertical tubular loop bioreactor (VTLB) at optimum condition determined in the bubble column bioreactor. The PHB content of biomass was 51.6% w/w of cell dry weight (CDW) in the VTLB. These results indicated that the loop bioreactors specially are suitable candidates for PHB production from natural gas.
Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H(2) to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3mm and 6mm beads, five different modules of HFRs, and the STR. The analysis was performed using O(2) as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062h(-1)), followed by the TBR with 6mm beads (421h(-1)), and then the STR (114h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed.
Synthesis gas is readily obtained by gasifying coal, oil, biomass, or waste organics and represents an abundant, potentially inexpensive, feedstock for bioprocessing. The primary components of synthesis gas, carbon monoxide and hydrogen, can be converted into methane, organic acids, and alcohols via anaerobic fermentations. Bioconversion of synthesis gas is an attractive alternative to catalytic processing because the biological catalysts are highly specific and often more tolerant of sulfur contaminants than inorganic catalysts. However, because the aqueous solubilities of carbon monoxide and hydrogen are low, synthesis-gas fermentations are typically limited by the rate of gas-to-liquid mass transfer. Consequently, a major engineering challenge in commercial development of synthesis-gas fermentations is to provide sufficient gas mass transfer in an energy-efficient manner. This paper reviews recent progress in the development of synthesis-gas fermentations, with emphasis on efforts to increase the efficiency of gas mass transfer. Metabolic properties of several microbes able to ferment synthesis gas are described. Results of synthesis-gas fermentations conducted in various bioreactor configurations are summarized. Recent results showing enhancement of synthesis-gas fermentations using microbubble dispersions are presented, and studies of the mass-transfer and coalescence properties of microbubbles are described.
In this study, the volumetric mass transfer coefficients (Ka) for CO were examined in a composite hollow fiber (CHF) membrane bioreactor. The mass transfer experiments were conducted at various inlet gas pressures (from 5 to 30psig (34.5-206.8kPa(g))) and recirculation flow rates (300, 600, 900, 1200 and 1500mL/min) through CHF module. The highest Ka value of 946.61/h was observed at a recirculation rate of 1500mL/min and at an inlet gas pressure of 30psig(206.8kPa(g)). The findings of this study confirm that the use of CHF membranes is effective and improves the efficiency CO mass transfer into the aqueous phase.
Diffusion of the electron acceptor is the rate controlling step in virtually all biofilm reactors employed for aerobic wastewater treatment. The membrane-aerated biofilm reactor (MABR) is a technology that can deliver oxygen at high rates and transfer efficiencies, thereby enhancing the biofilm activity. This paper provides a comparative performance rate analysis of the MABR in terms of its application for carbonaceous pollutant removal, nitrification/denitrification and xenobiotic biotreatment. We also describe the mechanisms influencing process performance in the MABR and the inter-relationships between these factors. The challenges involved in scaling-up the process are discussed with recommendations for prioritization of research needs.
Production of Lactic Acid by Ralstonia Eutropha H16, a Gram-Negative Chemolithoautotroph, Using Tools of Synthetic Biology, MSc
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A. Holohan, Production of Lactic Acid by Ralstonia Eutropha H16, a Gram-Negative Chemolithoautotroph, Using Tools of Synthetic Biology, MSc,
Biomolecular and Biomedical Science, University College Dublin, 2021.
How to Scale-Out and Scale-Up Cell Therapy Production
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