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Zuo Z, Niu C, Zhao X, Lai CY, Zheng M, Guo J, Hu S, Liu T. Biological bromate reduction coupled with in situ gas fermentation in H 2/CO 2-based membrane biofilm reactor. WATER RESEARCH 2024; 254:121402. [PMID: 38461600 DOI: 10.1016/j.watres.2024.121402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 01/12/2024] [Accepted: 02/28/2024] [Indexed: 03/12/2024]
Abstract
Bromate, a carcinogenic contaminant generated in water disinfection, presents a pressing environmental concern. While biological bromate reduction is an effective remediation approach, its implementation often necessitates the addition of organics, incurring high operational costs. This study demonstrated the efficient biological bromate reduction using H2/CO2 mixture as the feedstock. A membrane biofilm reactor (MBfR) was used for the efficient delivery of gases. Long-term reactor operation showed a high-level bromate removal efficiency of above 95 %, yielding harmless bromide as the final product. Corresponding to the short hydraulic retention time of 0.25 d, a high bromate removal rate of 4 mg Br/L/d was achieved. During the long-term operation, in situ production of volatile fatty acids (VFAs) by gas fermentation was observed, which can be regulated by controlling the gas flow. Three sets of in situ batch tests and two groups of ex situ batch tests jointly unravelled the mechanisms underpinning the efficient bromate removal, showing that the microbial bromate reduction was primarily driven by the VFAs produced from in situ gas fermentation. Microbial community analysis showed an increased abundance of Bacteroidota group from 4.0 % to 18.5 %, which is capable of performing syngas fermentation, and the presence of heterotrophic denitrifiers (e.g., Thauera and Brachymonas), which are known to perform bromate reduction. Together these results for the first time demonstrated the feasibility of using H2/CO2 mixture for bromate removal coupled with in situ VFAs production. The findings can facilitate the development of cost-effective strategies for groundwater and drinking water remediation.
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Affiliation(s)
- Zhiqiang Zuo
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia; National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Chenkai Niu
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Xinyu Zhao
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Chun-Yu Lai
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia; College of Environmental and Resource Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Min Zheng
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Jianhua Guo
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Shihu Hu
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Tao Liu
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St. Lucia, Queensland 4072, Australia; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China.
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Fernández-Blanco C, Veiga MC, Kennes C. Carbon dioxide as key player in chain elongation and growth of Clostridium kluyveri: Insights from batch and bioreactor studies. BIORESOURCE TECHNOLOGY 2024; 394:130192. [PMID: 38081469 DOI: 10.1016/j.biortech.2023.130192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/07/2023] [Accepted: 12/08/2023] [Indexed: 02/04/2024]
Abstract
Chain elongation technology allows medium-chain fatty acids (MCFAs) production as an alternative to fossil resources. Clostridium kluyveri generates n-caproate primarily from ethanol and acetate, presumably requiring CO2 for growth. Here, the impact of CO2 on C. kluyveri was explored. Bottle studies revealed the bacterium's adaptability to low CO2 levels, even in conditions with minimal dissolved NaHCO3 (0.0003 M) and unfavorable pH (below 6) under 1 bar CO2. Bioreactor investigations demonstrated a direct correlation between CO2 availability and bacterial growth. The highest n-caproate production (11.0 g/L) with 90.1 % selectivity was achieved in a bioreactor with continuous CO2 supply at 3 mL/min. Additional bottle experiments pressurized with 1 bar CO2 and varying ethanol:acetate ratios (1:1, 2:1, 4:1) also confirmed CO2 consumption by C. kluyveri. However, increasing the ethanol:acetate ratio did not enhance n-caproate selectivity, likely due to overly acidic pH conditions. These findings provide insights into chain-elongators responses under diverse conditions.
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Affiliation(s)
- Carla Fernández-Blanco
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology, Centro Interdisciplinar de Química e Bioloxía (CICA), BIOENGIN Group, University of A Coruña, E-15008-A Coruña, Spain
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology, Centro Interdisciplinar de Química e Bioloxía (CICA), BIOENGIN Group, University of A Coruña, E-15008-A Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology, Centro Interdisciplinar de Química e Bioloxía (CICA), BIOENGIN Group, University of A Coruña, E-15008-A Coruña, Spain.
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Fernández-Blanco C, Veiga MC, Kennes C. Effect of pH and medium composition on chain elongation with Megasphaera hexanoica producing C 4-C 8 fatty acids. Front Microbiol 2023; 14:1281103. [PMID: 38029098 PMCID: PMC10653306 DOI: 10.3389/fmicb.2023.1281103] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Chain elongation technology, which involves fermentation with anaerobic bacteria, has gained attention for converting short and medium chain substrates into valuable and longer-chain products like medium chain fatty acids (MCFAs). In the recent past, the focus of studies with pure chain elongating cultures was on species of other genera, mainly Clostridium kluyveri. Recently, other chain elongators have been isolated that deserve further research, such as Megasphaera hexanoica. Methods In this study, batch studies were performed in bottles with two different media to establish the optimal conditions for growth of M. hexanoica: (a) a medium rich in different sources of nitrogen and (b) a medium whose only source of nitrogen is yeast extract. Also, batch bioreactor studies at pH values of 5.8, 6.5 and 7.2 were set up to study the fermentation of lactate (i.e., electron donor) and acetate (i.e., electron acceptor) by M. hexanoica. Results and discussion Batch bottle studies revealed the yeast extract (YE) containing medium as the most promising in terms of production/cost ratio, producing n-caproate rapidly up to 2.62 ± 0.24 g/L. Subsequent bioreactor experiments at pH 5.8, 6.5, and 7.2 confirmed consistent production profiles, yielding C4-C8 fatty acids. A fourth bioreactor experiment at pH 6.5 and doubling both lactate and acetate concentrations enhanced MCFA production, resulting in 3.7 g/L n-caproate and 1.5 g/L n-caprylate. H2 and CO2 production was observed in all fermentations, being especially high under the increased substrate conditions. Overall, this study provides insights into M. hexanoica's behavior in lactate-based chain elongation and highlights optimization potential for improved productivity.
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Affiliation(s)
| | | | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology – Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN Group, University of A Coruña, Coruña, Spain
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Seid N, Ochsenreither K, Neumann A. Caproate production from Enset fiber in one-pot two-step fermentation using anaerobic fungi (Neocallimastix cameroonii strain G341) and Clostridium kluyveri DSM 555. Microb Cell Fact 2023; 22:216. [PMID: 37864174 PMCID: PMC10588050 DOI: 10.1186/s12934-023-02224-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 10/06/2023] [Indexed: 10/22/2023] Open
Abstract
BACKGROUND Lignocellulosic biomass plays a crucial role in creating a circular bioeconomy and minimizing environmental impact. Enset biomass is a byproduct of traditional Ethiopian Enset food processing that is thrown away in huge quantities. This study aimed to produce caproate from Enset fiber using Neocallimastix cameroonii strain G341 and Clostridium kluyveri DSM 555 in one-pot two-step fermentation. RESULTS The process started by growing N. cameroonii on Enset fiber as a carbon source for 7 days. Subsequently, the fungal culture was inoculated with active C. kluyveri preculture and further incubated. The results showed that N. cameroonii grew on 0.25 g untreated Enset fiber as the sole carbon source and produced 1.16 mmol acetate, 0.51 mmol hydrogen, and 1.34 mmol formate. In addition, lactate, succinate, and ethanol were detected in small amounts, 0.17 mmol, 0.08 mmol, and 0.7 mmol, respectively. After inoculating with C. kluyveri, 0.3 mmol of caproate and 0.48 mmol of butyrate were produced, and hydrogen production also increased to 0.95 mmol compared to sole N. cameroonii fermentation. Moreover, after the culture was supplemented with 2.18 mmol of ethanol during C. kluyveri inoculation, caproate, and hydrogen production was further increased to 1.2 and 1.36 mmol, respectively, and the consumption of acetate also increased. CONCLUSION A novel microbial cell factory was developed to convert untreated lignocellulosic Enset fiber into the medium chain carboxylic acid caproate and H2 by a co-culture of the anaerobic fungi N. cameroonii and C. kluyveri. This opens a new value chain for Enset farmers, as the process requires only locally available raw materials and low-price fermenters. As the caproate production was mainly limited by the available ethanol, the addition of locally produced ethanol-containing fermentation broth ("beer") would further increase the titer.
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Affiliation(s)
- Nebyat Seid
- Electrobiotechnology, Institute of Process Engineering in Life Science 2, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany.
- School of Chemical and Bio Engineering, Addis Ababa Institute of Technology, Addis Ababa University, P.O.B: 1176, Addis Ababa, Ethiopia.
| | - Katrin Ochsenreither
- Department of Chemical and Process Engineering, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Anke Neumann
- Electrobiotechnology, Institute of Process Engineering in Life Science 2, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany.
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Parera Olm I, Sousa DZ. Upgrading dilute ethanol to odd-chain carboxylic acids by a synthetic co-culture of Anaerotignum neopropionicum and Clostridium kluyveri. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:83. [PMID: 37194097 DOI: 10.1186/s13068-023-02336-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/03/2023] [Indexed: 05/18/2023]
Abstract
BACKGROUND Dilute ethanol streams generated during fermentation of biomass or syngas can be used as feedstocks for the production of higher value products. In this study, we describe a novel synthetic microbial co-culture that can effectively upgrade dilute ethanol streams to odd-chain carboxylic acids (OCCAs), specifically valerate and heptanoate. The co-culture consists of two strict anaerobic microorganisms: Anaerotignum neopropionicum, a propionigenic bacterium that ferments ethanol, and Clostridium kluyveri, well-known for its chain-elongating metabolism. In this co-culture, A. neopropionicum grows on ethanol and CO2 producing propionate and acetate, which are then utilised by C. kluyveri for chain elongation with ethanol as the electron donor. RESULTS A co-culture of A. neopropionicum and C. kluyveri was established in serum bottles with 50 mM ethanol, leading to the production of valerate (5.4 ± 0.1 mM) as main product of ethanol-driven chain elongation. In a continuous bioreactor supplied with 3.1 g ethanol L-1 d-1, the co-culture exhibited high ethanol conversion (96.6%) and produced 25% (mol/mol) valerate, with a steady-state concentration of 8.5 mM and a rate of 5.7 mmol L-1 d-1. In addition, up to 6.5 mM heptanoate was produced at a rate of 2.9 mmol L-1 d-1. Batch experiments were also conducted to study the individual growth of the two strains on ethanol. A. neopropionicum showed the highest growth rate when cultured with 50 mM ethanol (μmax = 0.103 ± 0.003 h-1) and tolerated ethanol concentrations of up to 300 mM. Cultivation experiments with C. kluyveri showed that propionate and acetate were used simultaneously for chain elongation. However, growth on propionate alone (50 mM and 100 mM) led to a 1.8-fold reduction in growth rate compared to growth on acetate. Our results also revealed sub-optimal substrate use by C. kluyveri during odd-chain elongation, where excessive ethanol was oxidised to acetate. CONCLUSIONS This study highlights the potential of synthetic co-cultivation in chain elongation processes to target the production of OCCAs. Furthermore, our findings shed light on to the metabolism of odd-chain elongation by C. kluyveri.
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Affiliation(s)
- Ivette Parera Olm
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands.
- Centre for Living Technologies, Eindhoven-Wageningen-Utrecht Alliance, Utrecht, The Netherlands.
| | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
- Centre for Living Technologies, Eindhoven-Wageningen-Utrecht Alliance, Utrecht, The Netherlands
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Bäumler M, Burgmaier V, Herrmann F, Mentges J, Schneider M, Ehrenreich A, Liebl W, Weuster-Botz D. Continuous Production of Ethanol, 1-Butanol and 1-Hexanol from CO with a Synthetic Co-Culture of Clostridia Applying a Cascade of Stirred-Tank Bioreactors. Microorganisms 2023; 11:microorganisms11041003. [PMID: 37110426 PMCID: PMC10144111 DOI: 10.3390/microorganisms11041003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/06/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
Syngas fermentation with clostridial co-cultures is promising for the conversion of CO to alcohols. A CO sensitivity study with Clostridium kluyveri monocultures in batch operated stirred-tank bioreactors revealed total growth inhibition of C. kluyveri already at 100 mbar CO, but stable biomass concentrations and ongoing chain elongation at 800 mbar CO. On/off-gassing with CO indicated a reversible inhibition of C. kluyveri. A continuous supply of sulfide led to increased autotrophic growth and ethanol formation by Clostridium carboxidivorans even at unfavorable low CO concentrations. Based on these results, a continuously operated cascade of two stirred-tank reactors was established with a synthetic co-culture of both Clostridia. An amount of 100 mbar CO and additional sulfide supply enabled growth and chain elongation in the first bioreactor, whereas 800 mbar CO resulted in an efficient reduction of organic acids and de-novo synthesis of C2-C6 alcohols in the second reactor. High alcohol/acid ratios of 4.5-9.1 (w/w) were achieved in the steady state of the cascade process, and the space-time yields of the alcohols produced were improved by factors of 1.9-5.3 compared to a batch process. Further improvement of continuous production of medium chain alcohols from CO may be possible by applying less CO-sensitive chain-elongating bacteria in co-cultures.
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Affiliation(s)
- Miriam Bäumler
- Chair of Biochemical Engineering, Department of Energy and Process Engineering, TUM School of Engineering and Design, Technical University of Munich, 85748 Garching, Germany
| | - Veronika Burgmaier
- Chair of Biochemical Engineering, Department of Energy and Process Engineering, TUM School of Engineering and Design, Technical University of Munich, 85748 Garching, Germany
| | - Fabian Herrmann
- Chair of Biochemical Engineering, Department of Energy and Process Engineering, TUM School of Engineering and Design, Technical University of Munich, 85748 Garching, Germany
| | - Julian Mentges
- Chair of Biochemical Engineering, Department of Energy and Process Engineering, TUM School of Engineering and Design, Technical University of Munich, 85748 Garching, Germany
| | - Martina Schneider
- Chair of Microbiology, TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany
| | - Armin Ehrenreich
- Chair of Microbiology, TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany
| | - Wolfgang Liebl
- Chair of Microbiology, TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany
| | - Dirk Weuster-Botz
- Chair of Biochemical Engineering, Department of Energy and Process Engineering, TUM School of Engineering and Design, Technical University of Munich, 85748 Garching, Germany
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Konstantinidi S, Skiadas IV, Gavala HN. Microbial Enrichment Techniques on Syngas and CO2 Targeting Production of Higher Acids and Alcohols. Molecules 2023; 28:molecules28062562. [PMID: 36985533 PMCID: PMC10056454 DOI: 10.3390/molecules28062562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 03/15/2023] Open
Abstract
(1) Background: Microbial conversion of gaseous molecules, such as CO2, CO and H2, to valuable compounds, has come to the forefront since the beginning of the 21st century due to increasing environmental concerns and the necessity to develop alternative technologies that contribute to a fast transition to a more sustainable era. Research efforts so far have focused on C1–C2 molecules, i.e., ethanol and methane, while interest in molecules with higher carbon atoms has also started to emerge. Research efforts have already started to pay off, and industrial installments on ethanol production from steel-mill off-gases as well as methane production from the CO2 generated in biogas plants are a reality. (2) Methodology: The present study addresses C4–C6 acids and butanol as target molecules and responds to how the inherent metabolic potential of mixed microbial consortia could be revealed and exploited based on the application of different enrichment methods (3) Results and Conclusions: In most of the enrichment series, the yield of C4–C6 acids was enhanced with supplementation of acetic acid and ethanol together with the gas substrates, resulting in a maximum of 43 and 68% (e-mol basis) for butyric and caproic acid, respectively. Butanol formation was also enhanced, to a lesser degree though and up to 9% (e-mol basis). Furthermore, the microbial community exhibited significant shifts depending on the enrichment conditions applied, implying that a more profound microbial analysis on the species level taxonomy combined with the development of minimal co-cultures could set the basis for discovering new microbial co-cultures and/or co-culturing schemes.
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Jin X, Yin X, Ling L, Mao H, Dong X, Chang X, Chen M, Fang S. Adding glucose delays the conversion of ethanol and acetic acid to caproic acid in Lacrimispora celerecrescens JSJ-1. Appl Microbiol Biotechnol 2023; 107:1453-1463. [PMID: 36703009 DOI: 10.1007/s00253-023-12378-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 01/07/2023] [Accepted: 01/10/2023] [Indexed: 01/28/2023]
Abstract
Caproic acid is an important fatty acid with diverse applications. In this study, the biomass growth and metabolites of Lacrimispora celerecrescens JSJ-1 were investigated under different carbon sources (ethanol, starch, sucrose, and glucose), with a focus on the effect of the coexistence of glucose and ethanol on the synthesis of caproic acid. The results showed that starch, glucose, and sucrose all contributed to the biomass of L. celerecrescens JSJ-1. Under the three carbon sources, L. celerecrescens JSJ-1 produced acetic acid, butyric acid, lactic acid, ethanol, and butanol, but caproic acid was not produced. Ethanol was the optimal substrate for the production of caproic acid. When glucose and ethanol coexisted, the generation time of caproic acid was delayed compared with that in ethanol sodium acetate medium (ES medium). This was because glucose was preferentially consumed over ethanol. Lactic acid was generated as a result of glucose consumption, which led to a significant decrease in pH from 6.45 to 4.68. The low pH (< 5) inhibited the synthesis of caproic acid. Then, the strain's usage of lactic acid and the reaction between CaCO3 and lactic acid caused the pH to increase. L. celerecrescens JSJ-1 did not start producing caproic acid using ethanol and acetic acid until the pH increased to 5.8. This research enriches the knowledge regarding the metabolism of L. celerecrescens JSJ-1 and provides guidelines for the industrial production of caproic acid by using L. celerecrescences JSJ-1. KEY POINTS: • Ethanol is the optimal substrate for the synthesis of caproic acid by Lacrimispora celerecrescens JSJ-1. • Lacrimispora celerecrescens JSJ-1 produced lactic acid rapidly when it used glucose, causing a sharp drop in pH. • pH is a crucial factor affecting the synthesis of caproic acid from ethanol by Lacrimispora celerecrescens JSJ-1.
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Affiliation(s)
- Xiangyi Jin
- Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Food and Biological Engineering, Hubei University of Technology, Wuhan, 430068, China
| | - Xiangxiang Yin
- Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Food and Biological Engineering, Hubei University of Technology, Wuhan, 430068, China
| | - Li Ling
- Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Food and Biological Engineering, Hubei University of Technology, Wuhan, 430068, China
| | - Hao Mao
- Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Food and Biological Engineering, Hubei University of Technology, Wuhan, 430068, China
| | | | - Xu Chang
- Angel Yeast Co. Ltd, Yichang, 443200, China
| | - Maobin Chen
- Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Food and Biological Engineering, Hubei University of Technology, Wuhan, 430068, China
| | - Shangling Fang
- Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, School of Food and Biological Engineering, Hubei University of Technology, Wuhan, 430068, China.
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Long F, Fan J, Liu H. Prediction and optimization of medium-chain carboxylic acids production from food waste using machine learning models. BIORESOURCE TECHNOLOGY 2023; 370:128533. [PMID: 36574890 DOI: 10.1016/j.biortech.2022.128533] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/19/2022] [Accepted: 12/22/2022] [Indexed: 06/17/2023]
Abstract
Machine learning models were developed in this study to predict and optimize the medium-chain carbolic acids (MCCAs) production from food waste. All three selected prediction algorithms achieved decent performance (accuracy > 0.85, R2 > 0.707). Three optimization algorithms were applied for MCCA production optimization based on the prediction algorithms. The maximum MCCA production rate (0.68 g chemical oxygen demand per liter per day) was achieved by simulated annealing coupled with random forest under the optimal conditions of pH 8.3, temperature 50 °C, retention time 4 days, loading rate 15.8 g volatile solid per liter per day, and inoculum to food waste ratio 70:30 with semi-continuous mode. Further experiments validated (18 % error) that the MCCA production rate was 113 % higher than the highest production rate of current lab experiments and 60 % higher than the statistical optimization using response surface methodology. This study demonstrates the potential of using machine learning for MCCA production prediction and optimization.
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Affiliation(s)
- Fei Long
- Department of Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97331, USA
| | - Joshua Fan
- Crescent Valley High School, Corvallis, OR 97330, USA
| | - Hong Liu
- Department of Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97331, USA.
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Luo H, Li T, Zheng J, Zhang K, Qiao Z, Luo H, Zou W. Isolation, Identification, and Fermentation Medium Optimization of a Caproic Acid‑Producing Enterococcus casseliflavus Strain from Pit Mud of Chinese Strong Flavor Baijiu Ecosystem. Pol J Microbiol 2022; 71:563-575. [PMID: 36537057 PMCID: PMC9944964 DOI: 10.33073/pjm-2022-052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/11/2022] [Indexed: 12/24/2022] Open
Abstract
Caproic acid is the precursor material of ethyl hexanoate, a representative flavor substance in strong flavor baijiu (SFB). Increasing the content of caproic acid in SFB helps to improve its quality. In the present study, caproic acid-producing bacteria from the pit mud of an SFB ecosystem were isolated, purified, and characterized. Strain BF-1 with the highest caproic acid yield (0.88 g/l) was selected. The morphological and molecular identification analysis showed that strain BF-1 was Enterococcus casseliflavus. The genome of E. casseliflavus BF-1 was sequenced and was found to be 2,968,377 bp in length with 3,270 open reading frames (ORFs). The caproic acid biosynthesis pathway in E. casseliflavus BF-1 was predicted based on the KAAS annotation. The virulence factors in the genome of strain BF-1 were annotated, which showed that E. casseliflavus BF-1 is safe at the genetic level. After adding essential nutrients based on the KAAS annotation, the optimum medium conditions for acid production by strain BF-1 were obtained by performing orthogonal experiments. The caproic acid yield of strain BF-1 reached 3.03 g/l, which was 3.44-fold higher than the initial yield. The optimized fer- mentation of caproic acid production by BF-1 was reported for the first time. The strain could be further used to regulate the ecosystem in baijiu production to improve its quality.
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Affiliation(s)
- Hao Luo
- College of Bioengineering, Sichuan University of Science and Engineering, Yibin, China
| | - Tao Li
- Sichuan Vocational College of Chemical Technology, Luzhou, China
| | - Jia Zheng
- Wuliangye Yibin Co. Ltd., Yibin, China
| | - Kaizheng Zhang
- College of Bioengineering, Sichuan University of Science and Engineering, Yibin, China
| | | | - Huibo Luo
- College of Bioengineering, Sichuan University of Science and Engineering, Yibin, China
| | - Wei Zou
- College of Bioengineering, Sichuan University of Science and Engineering, Yibin, China, Wei Zou, College of Bioengineering, Sichuan University of Science and Engineering, Yibin, China
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Ricci L, Seifert A, Bernacchi S, Fino D, Pirri CF, Re A. Leveraging substrate flexibility and product selectivity of acetogens in two-stage systems for chemical production. Microb Biotechnol 2022; 16:218-237. [PMID: 36464980 PMCID: PMC9871533 DOI: 10.1111/1751-7915.14172] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/31/2022] [Accepted: 11/08/2022] [Indexed: 12/09/2022] Open
Abstract
Carbon dioxide (CO2 ) stands out as sustainable feedstock for developing a circular carbon economy whose energy supply could be obtained by boosting the production of clean hydrogen from renewable electricity. H2 -dependent CO2 gas fermentation using acetogenic microorganisms offers a viable solution of increasingly demonstrated value. While gas fermentation advances to achieve commercial process scalability, which is currently limited to a few products such as acetate and ethanol, it is worth taking the best of the current state-of-the-art technology by its integration within innovative bioconversion schemes. This review presents multiple scenarios where gas fermentation by acetogens integrate into double-stage biotechnological production processes that use CO2 as sole carbon feedstock and H2 as energy carrier for products' synthesis. In the integration schemes here reviewed, the first stage can be biotic or abiotic while the second stage is biotic. When the first stage is biotic, acetogens act as a biological platform to generate chemical intermediates such as acetate, formate and ethanol that become substrates for a second fermentation stage. This approach holds the potential to enhance process titre/rate/yield metrics and products' spectrum. Alternatively, when the first stage is abiotic, the integrated two-stage scheme foresees, in the first stage, the catalytic transformation of CO2 into C1 products that, in the second stage, can be metabolized by acetogens. This latter scheme leverages the metabolic flexibility of acetogens in efficient utilization of the products of CO2 abiotic hydrogenation, namely formate and methanol, to synthesize multicarbon compounds but also to act as flexible catalysts for hydrogen storage or production.
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Affiliation(s)
- Luca Ricci
- Department of Applied Science and TechnologyPolitecnico di TorinoTurinItaly,Centre for Sustainable Future TechnologiesFondazione Istituto Italiano di TecnologiaTurinItaly
| | | | | | - Debora Fino
- Department of Applied Science and TechnologyPolitecnico di TorinoTurinItaly,Centre for Sustainable Future TechnologiesFondazione Istituto Italiano di TecnologiaTurinItaly
| | - Candido Fabrizio Pirri
- Department of Applied Science and TechnologyPolitecnico di TorinoTurinItaly,Centre for Sustainable Future TechnologiesFondazione Istituto Italiano di TecnologiaTurinItaly
| | - Angela Re
- Department of Applied Science and TechnologyPolitecnico di TorinoTurinItaly,Centre for Sustainable Future TechnologiesFondazione Istituto Italiano di TecnologiaTurinItaly
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12
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Otten JK, Zou Y, Papoutsakis ET. The potential of caproate (hexanoate) production using Clostridium kluyveri syntrophic cocultures with Clostridium acetobutylicum or Clostridium saccharolyticum. Front Bioeng Biotechnol 2022; 10:965614. [PMID: 36072287 PMCID: PMC9441933 DOI: 10.3389/fbioe.2022.965614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/15/2022] [Indexed: 11/18/2022] Open
Abstract
Caproate (hexanoate) and other medium-chain fatty acids are valuable platform chemicals produced by processes utilizing petroleum or plant oil. Clostridium kluyveri, growing on short chain alcohols (notably ethanol) and carboxylic acids (such as acetate) is noted for its ability to perform chain elongation to produce 4- to 8-carbon carboxylates. C. kluyveri has been studied in monoculture and coculture conditions, which lead to relatively modest carboxylate titers after long fermentation times. To assess the biosynthetic potential of C. kluyveri for caproate production from sugars through coculture fermentations, in the absence of monoculture data in the literature suitable for our coculture experiments, we first explored C. kluyveri monocultures. Some monocultures achieved caproate titers of 150 to over 200 mM in 40–50 h with a production rate of 7.9 mM/h. Based on that data, we then explored two novel, syntrophic coculture partners for producing caproate from sugars: Clostridium acetobutylicum and Clostridium saccharolyticum. Neither species has been cocultured with C. kluyveri before, and both demonstrate promising results. Our experiments of C. kluyveri monocultures and C. kluyveri—C. saccharolyticum cocultures demonstrate exceptionally high caproate titers (145–200 mM), fast production rates (3.25–8.1 mM/h), and short fermentation times (18–45 h). These results represent the most caproate produced by a C. kluyveri coculture in the shortest known fermentation time. We also explored the possibility of heterologous cell fusion between the coculture pairs similar to the results seen previously in our group with C. acetobutylicum and Clostridium ljungdahlii. Fusion events were observed only in the C. acetobutylicum—C. kluyveri coculture pair, and we offer an explanation for the lack of fusion between C. saccharolyticum and C. kluyveri. This work supports the promise of coculture biotechnology for sustainable production of caproate and other platform chemicals.
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Affiliation(s)
- Jonathan K. Otten
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States
- Delaware Biotechnology Institute, University of Delaware, Newark, DE, United States
| | - Yin Zou
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States
| | - Eleftherios T. Papoutsakis
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States
- Delaware Biotechnology Institute, University of Delaware, Newark, DE, United States
- Department of Biological Sciences, University of Delaware, Newark, DE, United States
- *Correspondence: Eleftherios T. Papoutsakis,
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13
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Biofuels Production and Processing Technology. FERMENTATION 2022. [DOI: 10.3390/fermentation8070319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The negative global warming impact and global environmental pollution due to fossil fuels mean that the main challenge of modern society is finding alternatives to conventional fuels. In this scenario, biofuels derived from renewable biomass represent the most promising renewable energy sources. Depending on the biomass used by the fermentation technologies, it is possible obtain first-generation biofuels produced from food crops, second-generation biofuels produced from non-food feedstock, mainly starting from renewable lignocellulosic biomasses, and third-generation biofuels, represented by algae or food waste biomass. Although biofuels appear to be the closest alternative to fossil fuels, it is necessary for them to be produced in competitive quantities and costs, requiring both improvements to production technologies and diversification of feedstock. This Special Issue is focused on technological innovations, which include but are not limited to the utilization of different feedstock; different biomass pretreatments; fermentation strategies, such as simultaneous saccharification and fermentation (SSF) or separate hydrolysis and fermentation (SHF); different applied microorganisms used as monoculture or co-culture; and different setups for biofuel fermentation processes.
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14
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Xiang S, Wu Q, Ren W, Guo W, Ren N. Mechanism of powdered activated carbon enhancing caproate production. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2022.07.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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15
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The Measurement, Application and Effect of Oxygen in Microbial Fermentations: Focusing on Methane and Carboxylate Production. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8040138] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Oxygen is considered detrimental to anaerobic fermentation processes by many practitioners. However, deliberate oxygen sparging has been used successfully for decades to remove H2S in anaerobic digestion (AD) systems. Moreover, microaeration techniques during AD have shown that small doses of oxygen may enhance process performance and promote the in situ degradation of recalcitrant compounds. However, existing oxygen dosing techniques are imprecise, which has led to inconsistent results between studies. At the same time, real-time oxygen fluxes cannot be reliably quantified due to the complexity of most bioreactor systems. Thus, there is a pressing need for robust monitoring and process control in applications where oxygen serves as an operating parameter or an experimental variable. This review summarizes and evaluates the available methodologies for oxygen measurement and dosing as they pertain to anaerobic microbiomes. The historical use of (micro-)aeration in anaerobic digestion and its potential role in other anaerobic fermentation processes are critiqued in detail. This critique also provides insights into the effects of oxygen on these microbiomes. Our assessment suggests that oxygen dosing, when implemented in a controlled and quantifiable manner, could serve as an effective tool for bioprocess engineers to further manipulate anaerobic microbiomes for either bioenergy or biochemical production.
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16
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Wu Q, Ren W, Guo W, Ren N. Effect of substrate structure on medium chain fatty acids production and reactor microbiome. ENVIRONMENTAL RESEARCH 2022; 204:111947. [PMID: 34454935 DOI: 10.1016/j.envres.2021.111947] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/23/2021] [Accepted: 08/20/2021] [Indexed: 06/13/2023]
Abstract
The medium chain fatty acids (MCFAs) produced from organic wastes can replace part fossil-fuel-based products to promote the sustainable development of economy and environment. However, the selection and collocation of feedstocks for MCFAs production are lack of reference basis. This study thereby aimed to investigate how the commonly used electron donor (ED) and substrate configuration affect MCFAs synthesis and then obtain the optimal substrate composition. It was found that the optimized ratios for ethanol/acetate, lactate/acetate, and ethanol/lactate/acetate were 3/1, 2/1, and 2/1/1, respectively, and the optimal substrate concentration was 400 mM C. Combining ethanol and lactate as co-EDs effectively concentrated substrate-carbon-flow (increased by 20-28% than sole ED) on MCFAs synthesis by promoting the elongation of butyrate and reutilization of by-products. As a result, the higher MCFAs yield of 646.22 mg COD/g COD and selectivity of 67.72% were obtained from co-EDs than those from sole ED. Moreover, the key functional bacteria enriched under different ED were also discrepant, which were Clostridium sensu stricto for ethanol, Corynebacterium for lactate, and Veillonella and Oscillibacter for ethanol-lactate, respectively. This study provided a basic but significant reference for the scale-up MCFAs production.
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Affiliation(s)
- Qinglian Wu
- College of Architecture and Environment, Sichuan University, Chengdu, 610065, China
| | - Weitong Ren
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China
| | - Wanqian Guo
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.
| | - Nanqi Ren
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China
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17
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Characterization of a Novel Acetogen Clostridium sp. JS66 for Production of Acids and Alcohols: Focusing on Hexanoic Acid Production from Syngas. BIOTECHNOL BIOPROC E 2022. [DOI: 10.1007/s12257-021-0122-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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18
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Fernández-Blanco C, Veiga MC, Kennes C. Efficient production of n-caproate from syngas by a co-culture of Clostridium aceticum and Clostridium kluyveri. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 302:113992. [PMID: 34710762 DOI: 10.1016/j.jenvman.2021.113992] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/30/2021] [Accepted: 10/21/2021] [Indexed: 06/13/2023]
Abstract
In recent years, the possibility of merging technologies for waste recovery such as those based on syngas fermentation and chain elongation has been studied for the production of medium chain fatty acids (MCFAs) and bioalcohols, in an attempt to integrate the concept of circular economy in the industry. Nevertheless, one of the main issues of this approach is the pH mismatch between acetogens and chain elongating microorganisms. This work reports, for the first time, the suitability of a co-culture of C. aceticum and C. kluyveri metabolizing syngas at near neutral pH in stirred tank bioreactors. For this purpose, bioreactor studies were carried out with continuous syngas supply. In the first experiment, maximum concentrations of n-butyrate and n-caproate of 7.0 and 8.2 g/L, respectively, were obtained. In the second experiment, considerable amounts of n-butanol were produced as a result of the reduction, by C. aceticum, of the carboxylates already formed in the broth. In both experiments, ethanol was used as an exogenous electron agent at some point. Finally, batch bottle assays were performed with a pure culture of C. aceticum grown on CO in presence of n-butyrate to assess and confirm its ability to produce n-butanol, reaching concentrations up to 951 mg/L, with a n-butyrate conversion efficiency of 96%, which had never been reported before in this species. Therefore, this work contributes to the state of the art, presenting a novel system for the bioproduction of MCFAs by combining syngas fermentation and chain elongation at near neutral pH, as opposed to the acidic pH range used in all previously reported literature.
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Affiliation(s)
- Carla Fernández-Blanco
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), BIOENGIN Group, University of La Coruña, E-15008, La Coruña, Spain
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), BIOENGIN Group, University of La Coruña, E-15008, La Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), BIOENGIN Group, University of La Coruña, E-15008, La Coruña, Spain.
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19
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Kim H, Kang S, Sang BI. Metabolic cascade of complex organic wastes to medium-chain carboxylic acids: A review on the state-of-the-art multi-omics analysis for anaerobic chain elongation pathways. BIORESOURCE TECHNOLOGY 2022; 344:126211. [PMID: 34710599 DOI: 10.1016/j.biortech.2021.126211] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/18/2021] [Accepted: 10/20/2021] [Indexed: 06/13/2023]
Abstract
Medium-chain carboxylic acid (MCCA) production from organic wastes has attracted much attention because of their higher energy contents and diverse applications. Anaerobic reactor microbiomes are stable and resilient and have resulted in efficient performance during many years of operation for thousands of full-scale anaerobic digesters worldwide. The method underlying how the relevant microbial pathways contribute to elongate carbon chains in reactor microbiomes is important. In particular, the reverse β-oxidation pathway genes are critical to upgrading short-chain fermentation products to MCCAs via a chain elongation (CE) process. Diverse genomics and metagenomics studies have been conducted in various fields, ranging from intracellular metabolic pathways to metabolic cascades between different strains. This review covers taxonomic approach to culture processes depending on types of organic wastes and the deeper understanding of genome and metagenome-scale CE pathway construction, and the co-culture and multi-omics technology that should be addressed in future research.
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Affiliation(s)
- Hyunjin Kim
- Department of Chemical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Seongcheol Kang
- Department of Chemical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Byoung-In Sang
- Department of Chemical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
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20
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Wang J, Yin Y. Biological production of medium-chain carboxylates through chain elongation: An overview. Biotechnol Adv 2021; 55:107882. [PMID: 34871718 DOI: 10.1016/j.biotechadv.2021.107882] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/01/2021] [Accepted: 11/28/2021] [Indexed: 12/15/2022]
Abstract
Medium chain carboxylates (MCCs) have wide applications in various industries, but the traditional MCCs production methods are costly and unsustainable. Anaerobic fermentation offers a more scalable, economical and eco-friendly platform for producing MCCs through chain elongation which converts short chain carboxylates and electron donor into more valuable MCCs. However, the underlying microbial pathways are not well understood. In this review, biological production of MCCs through chain elongation is introduced elaborately, including the metabolic pathways, electron donor and substrates, microorganisms and influencing factors. Then, the strategies for enhancing MCCs production are extensively analyzed and summarized, along with the technologies for MCCs separation from the fermentation broth. Finally, challenges and perspectives concerning the large-scale MCCs production are proposed, providing suggestions for the future research. Extensive review demonstrated that anaerobic fermentation has great potential in achieving economical and sustainable MCCs production from complex organic substrates, including organic waste streams, which would significantly broaden the application of MCCs, especially in the renewable energy field. An interdisciplinary approach with knowledge from microbiology and biochemistry to chemical separations and environmental engineering is required to use this promising technology as a valorization method for converting organic biomass or organic wastes into valuable MCCs.
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Affiliation(s)
- Jianlong Wang
- Laboratory of Environmental Technology, INET, Tsinghua University, Beijing 100084, PR China; Beijing Key Laboratory of Radioactive Waste Treatment, Tsinghua University, Beijing 100084, PR China.
| | - Yanan Yin
- Laboratory of Environmental Technology, INET, Tsinghua University, Beijing 100084, PR China
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21
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Dhakal N, Acharya B. Syngas Fermentation for the Production of Bio-Based Polymers: A Review. Polymers (Basel) 2021; 13:polym13223917. [PMID: 34833218 PMCID: PMC8618084 DOI: 10.3390/polym13223917] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 11/04/2021] [Accepted: 11/09/2021] [Indexed: 11/21/2022] Open
Abstract
Increasing environmental awareness among the general public and legislators has driven this modern era to seek alternatives to fossil-derived products such as fuel and plastics. Addressing environmental issues through bio-based products driven from microbial fermentation of synthetic gas (syngas) could be a future endeavor, as this could result in both fuel and plastic in the form of bioethanol and polyhydroxyalkanoates (PHA). Abundant availability in the form of cellulosic, lignocellulosic, and other organic and inorganic wastes presents syngas catalysis as an interesting topic for commercialization. Fascination with syngas fermentation is trending, as it addresses the limitations of conventional technologies like direct biochemical conversion and Fischer–Tropsch’s method for the utilization of lignocellulosic biomass. A plethora of microbial strains is available for syngas fermentation and PHA production, which could be exploited either in an axenic form or in a mixed culture. These microbes constitute diverse biochemical pathways supported by the activity of hydrogenase and carbon monoxide dehydrogenase (CODH), thus resulting in product diversity. There are always possibilities of enzymatic regulation and/or gene tailoring to enhance the process’s effectiveness. PHA productivity drags the techno-economical perspective of syngas fermentation, and this is further influenced by syngas impurities, gas–liquid mass transfer (GLMT), substrate or product inhibition, downstream processing, etc. Product variation and valorization could improve the economical perspective and positively impact commercial sustainability. Moreover, choices of single-stage or multi-stage fermentation processes upon product specification followed by microbial selection could be perceptively optimized.
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22
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Fan YX, Zhang JZ, Zhang Q, Ma XQ, Liu ZY, Lu M, Qiao K, Li FL. Biofuel and chemical production from carbon one industry flux gas by acetogenic bacteria. ADVANCES IN APPLIED MICROBIOLOGY 2021; 117:1-34. [PMID: 34742365 DOI: 10.1016/bs.aambs.2021.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Carbon one industry flux gas generated from fossil fuels, various industrial and domestic waste, as well as lignocellulosic biomass provides an innovative raw material to lead the sustainable development. Through the chemical and biological processing, the gas mixture composed of CO, CO2, and H2, also termed as syngas, is converted to biofuels and high-value chemicals. Here, the syngas fermentation process is elaborated to provide an overview. Sources of syngas are summarized and the influences of impurities on biological fermentation are exhibited. Acetogens and carboxydotrophs are the two main clusters of syngas utilizing microorganisms, their essential characters are presented, especially the energy metabolic scheme with CO, CO2, and H2. Synthetic biology techniques and microcompartment regulation are further discussed and proposed to create a high-efficiency cell factory. Moreover, the influencing factors in fermentation and products in carboxylic acids, alcohols, and others such like polyhydroxyalkanoate and poly-3-hydroxybutyrate are addressed. Biological fermentation from carbon one industry flux gas is a promising alternative, the latest scientific advances are expatiated hoping to inspire more creative transformation.
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Affiliation(s)
- Yi-Xuan Fan
- Shandong Provincial Key Laboratory of Synthetic Biology, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jun-Zhe Zhang
- Shandong Provincial Key Laboratory of Synthetic Biology, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Quan Zhang
- Sinopec Dalian (Fushun) Research Institute of Petroleum and Petrochemicals, Dalian, China
| | - Xiao-Qing Ma
- Shandong Provincial Key Laboratory of Synthetic Biology, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China
| | - Zi-Yong Liu
- Shandong Provincial Key Laboratory of Synthetic Biology, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China
| | - Ming Lu
- Shandong Provincial Key Laboratory of Synthetic Biology, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China
| | - Kai Qiao
- Sinopec Dalian (Fushun) Research Institute of Petroleum and Petrochemicals, Dalian, China.
| | - Fu-Li Li
- Shandong Provincial Key Laboratory of Synthetic Biology, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Dalian National Laboratory for Clean Energy, Dalian, China.
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23
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Ayol A, Peixoto L, Keskin T, Abubackar HN. Reactor Designs and Configurations for Biological and Bioelectrochemical C1 Gas Conversion: A Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph182111683. [PMID: 34770196 PMCID: PMC8583215 DOI: 10.3390/ijerph182111683] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/22/2021] [Accepted: 11/03/2021] [Indexed: 11/16/2022]
Abstract
Microbial C1 gas conversion technologies have developed into a potentially promising technology for converting waste gases (CO2, CO) into chemicals, fuels, and other materials. However, the mass transfer constraint of these poorly soluble substrates to microorganisms is an important challenge to maximize the efficiencies of the processes. These technologies have attracted significant scientific interest in recent years, and many reactor designs have been explored. Syngas fermentation and hydrogenotrophic methanation use molecular hydrogen as an electron donor. Furthermore, the sequestration of CO2 and the generation of valuable chemicals through the application of a biocathode in bioelectrochemical cells have been evaluated for their great potential to contribute to sustainability. Through a process termed microbial chain elongation, the product portfolio from C1 gas conversion may be expanded further by carefully driving microorganisms to perform acetogenesis, solventogenesis, and reverse β-oxidation. The purpose of this review is to provide an overview of the various kinds of bioreactors that are employed in these microbial C1 conversion processes.
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Affiliation(s)
- Azize Ayol
- Department of Environmental Engineering, Dokuz Eylul University, Izmir 35390, Turkey;
| | - Luciana Peixoto
- Centre of Biological Engineering (CEB), University of Minho, 4710-057 Braga, Portugal;
| | - Tugba Keskin
- Department of Environmental Protection Technologies, Izmir Democracy University, Izmir 35140, Turkey;
| | - Haris Nalakath Abubackar
- Chemical Engineering Laboratory, BIOENGIN Group, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of A Coruña, 15008 A Coruña, Spain
- Correspondence:
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24
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Wu Q, Jiang Y, Chen Y, Liu M, Bao X, Guo W. Opportunities and challenges in microbial medium chain fatty acids production from waste biomass. BIORESOURCE TECHNOLOGY 2021; 340:125633. [PMID: 34315125 DOI: 10.1016/j.biortech.2021.125633] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/16/2021] [Accepted: 07/17/2021] [Indexed: 06/13/2023]
Abstract
Medium chain fatty acids (MCFAs) that produced from affordable waste biomass via chain elongation (CE) technology are recognized as the potential alternatives to part fossil-derived chemicals, contributing to the sustainable development of economy and environment. The purpose of this review is to provide comprehensive analyses on the opportunities and challenges of MCFAs production and application. First, both two microbial MCFAs synthesis pathways of reverse β-oxidation and fatty acid biosynthesis were introduced/compared in detail to give readers a thorough understanding of the CE process, with the expectation of further boosting MCFAs production by well distinguishing them. Furthermore, the six key MCFAs production bottlenecks, corresponding research progresses, and possible solutions were analyzed. Five major MCFAs production strategies with their production mechanism, performances, and characteristics were also critically assessed. Additionally, the commercial production status was introduced, and future alternative production mode and research priorities were also recommended.
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Affiliation(s)
- Qinglian Wu
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China
| | - Yong Jiang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Ying Chen
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China
| | - Min Liu
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China
| | - Xian Bao
- School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798, Singapore.
| | - Wanqian Guo
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
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25
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Bäumler M, Schneider M, Ehrenreich A, Liebl W, Weuster-Botz D. Synthetic co-culture of autotrophic Clostridium carboxidivorans and chain elongating Clostridium kluyveri monitored by flow cytometry. Microb Biotechnol 2021; 15:1471-1485. [PMID: 34669248 PMCID: PMC9049614 DOI: 10.1111/1751-7915.13941] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 09/22/2021] [Accepted: 09/23/2021] [Indexed: 01/21/2023] Open
Abstract
Syngas fermentation with acetogens is known to produce mainly acetate and ethanol efficiently. Co-cultures with chain elongating bacteria making use of these products are a promising approach to produce longer-chain alcohols. Synthetic co-cultures with identical initial cell concentrations of Clostridium carboxidivorans and Clostridium kluyveri were studied in batch-operated stirred-tank bioreactors with continuous CO/CO2 -gassing and monitoring of the cell counts of both clostridia by flow cytometry after fluorescence in situ hybridization (FISH-FC). At 800 mbar CO, chain elongation activity was observed at pH 6.0, although growth of C. kluyveri was restricted. Organic acids produced by C. kluyveri were reduced by C. carboxidivorans to the corresponding alcohols butanol and hexanol. This resulted in a threefold increase in final butanol concentration and enabled hexanol production compared with a mono-culture of C. carboxidivorans. At 100 mbar CO, growth of C. kluyveri was improved; however, the capacity of C. carboxidivorans to form alcohols was reduced. Because of the accumulation of organic acids, a constant decay of C. carboxidivorans was observed. The measurement of individual cell concentrations in co-culture established in this study may serve as an effective tool for knowledge-based identification of optimum process conditions for enhanced formation of longer-chain alcohols by clostridial co-cultures.
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Affiliation(s)
- Miriam Bäumler
- Institute of Biochemical Engineering, TUM School of Engineering and Design, Technical University of Munich, Boltzmannstr. 15, Garching, 85748, Germany
| | - Martina Schneider
- Chair of Microbiology, TUM School of Life Sciences, Technical University of Munich, Emil-Ramann-Str. 4, Freising, Germany
| | - Armin Ehrenreich
- Chair of Microbiology, TUM School of Life Sciences, Technical University of Munich, Emil-Ramann-Str. 4, Freising, Germany
| | - Wolfgang Liebl
- Chair of Microbiology, TUM School of Life Sciences, Technical University of Munich, Emil-Ramann-Str. 4, Freising, Germany
| | - Dirk Weuster-Botz
- Institute of Biochemical Engineering, TUM School of Engineering and Design, Technical University of Munich, Boltzmannstr. 15, Garching, 85748, Germany
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Duan H, He P, Shao L, Lü F. Functional genome-centric view of the CO-driven anaerobic microbiome. THE ISME JOURNAL 2021; 15:2906-2919. [PMID: 33911204 PMCID: PMC8443622 DOI: 10.1038/s41396-021-00983-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 03/17/2021] [Accepted: 04/09/2021] [Indexed: 02/02/2023]
Abstract
CO is a promising substrate for producing biochemicals and biofuels through mixed microbial cultures, where carboxydotrophs play a crucial role. The previous investigations of mixed microbial cultures focused primarily on overall community structures, but under-characterized taxa and intricate microbial interactions have not yet been precisely explicated. Here, we undertook DNA-SIP based metagenomics to profile the anaerobic CO-driven microbiomes under 95 and 35% CO atmospheres. The time-series analysis of the isotope-labeled amplicon sequencing revealed the essential roles of Firmicutes and Proteobacteria under high and low CO pressure, respectively, and Methanobacterium was the predominant archaeal genus. The functional enrichment analysis based on the isotope-labeled metagenomes suggested that the microbial cultures under high CO pressure had greater potential in expressing carboxylate metabolism and citrate cycle pathway. The genome-centric metagenomics reconstructed 24 discovered and 24 under-characterized metagenome-assembled genomes (MAGs), covering more than 94% of the metagenomic reads. The metabolic reconstruction of the MAGs described their potential functions in the CO-driven microbiomes. Some under-characterized taxa might be versatile in multiple processes; for example, under-characterized Rhodoplanes sp. and Desulfitobacterium_A sp. could encode the complete enzymes in CO oxidation and carboxylate production, improving functional redundancy. Finally, we proposed the putative microbial interactions in the conversion of CO to carboxylates and methane.
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Affiliation(s)
- Haowen Duan
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, China
| | - Pinjing He
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, China
| | - Liming Shao
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, China
| | - Fan Lü
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, China.
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China.
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Residual Gas for Ethanol Production by Clostridium carboxidivorans in a Dual Impeller Stirred Tank Bioreactor (STBR). FERMENTATION-BASEL 2021. [DOI: 10.3390/fermentation7030199] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recycling residual industrial gases and residual biomass as substrates to biofuel production by fermentation is an important alternative to reduce organic wastes and greenhouse gases emission. Clostridium carboxidivorans can metabolize gaseous substrates as CO and CO2 to produce ethanol and higher alcohols through the Wood-Ljungdahl pathway. However, the syngas fermentation is limited by low mass transfer rates. In this work, a syngas fermentation was carried out in serum glass bottles adding different concentrations of Tween® 80 in ATCC® 2713 culture medium to improve gas-liquid mass transfer. We observed a 200% increase in ethanol production by adding 0.15% (v/v) of the surfactant in the culture medium and a 15% increase in biomass production by adding 0.3% (v/v) of the surfactant in the culture medium. The process was reproduced in stirred tank bioreactor with continuous syngas low flow, and a maximum ethanol productivity of 0.050 g/L.h was achieved.
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Gao M, Lin Y, Wang P, Jin Y, Wang Q, Ma H, Sheng Y, Van Le Q, Xia C, Lam SS. Production of medium-chain fatty acid caproate from Chinese liquor distillers' grain using pit mud as the fermentation microbes. JOURNAL OF HAZARDOUS MATERIALS 2021; 417:126037. [PMID: 33992013 DOI: 10.1016/j.jhazmat.2021.126037] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/09/2021] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
Chinese liquor distillers' grain (CLDG) is an abundant industrial organic waste showing high potential as feedstock for biofuel conversion. In this study, CLDG was used as substrate by microbial community in pit mud to produce medium-chain fatty acids (especially caproate). Simulated and real fermentation were used to evaluate the effect of ethanol and lactic acid being the electronic donors (EDs) during the anaerobic chain elongation (CE). The caproate concentration was achieved at 449 mg COD/g VS, with the corresponding high carbon selectivity at 37.1%. Microbial analysis revealed that the domestication of pit mud increased the abundance of Caproiciproducens (converting lactic acid into caproate) and Lactobacillus (producing lactic acid), leading to enhanced caproate production. The lactic acid conversion facilitated in full utilization of ethanol through CE consumption. The coexistence of EDs benefited the CE system and that this green energy production can be a promising high-performance biofuel donor for sustainable industrial production development.
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Affiliation(s)
- Ming Gao
- Department of Environmental Engineering, University of Science and Technology, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China; Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry, Beijing Technology and Business University, Beijing 100048, China
| | - Yujia Lin
- Department of Environmental Engineering, University of Science and Technology, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Pan Wang
- Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry, Beijing Technology and Business University, Beijing 100048, China
| | - Yong Jin
- Department of Environmental Engineering, University of Science and Technology, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Qunhui Wang
- Department of Environmental Engineering, University of Science and Technology, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China; Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry, Beijing Technology and Business University, Beijing 100048, China
| | - Hongzhi Ma
- Department of Environmental Engineering, University of Science and Technology, Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China; Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry, Beijing Technology and Business University, Beijing 100048, China.
| | - Yequan Sheng
- Co-Innovation Center of Efficient Processing and Utilization of Forestry Resources, College of Materials Science and Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Quyet Van Le
- Institute of Research and Development, Duy Tan University, Da Nang 550000, Viet Nam
| | - Changlei Xia
- Co-Innovation Center of Efficient Processing and Utilization of Forestry Resources, College of Materials Science and Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Su Shiung Lam
- Co-Innovation Center of Efficient Processing and Utilization of Forestry Resources, College of Materials Science and Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China; Higher Institution Centre of Excellence (HICoE), Institute of Tropical Aquaculture and Fisheries (AKUATROP), Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia; Henan Province Engineering Research Center for Biomass Value-added Products, School of Forestry, Henan Agricultural University, Zhengzhou 450002, China.
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Process Engineering Aspects for the Microbial Conversion of C1 Gases. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2021; 180:33-56. [PMID: 34291298 DOI: 10.1007/10_2021_172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Industrially applied bioprocesses for the reduction of C1 gases (CO2 and/or CO) are based in particular on (syn)gas fermentation with acetogenic bacteria and on photobioprocesses with microalgae. In each case, process engineering characteristics of the autotrophic microorganisms are specified and process engineering aspects for improving gas and electron supply are summarized before suitable bioreactor configurations are discussed for the production of organic products under given economic constraints. Additionally, requirements for the purity of C1 gases are summarized briefly. Finally, similarities and differences in microbial CO2 valorization are depicted comparing gas fermentations with acetogenic bacteria and photobioprocesses with microalgae.
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Allaart MT, Stouten GR, Sousa DZ, Kleerebezem R. Product Inhibition and pH Affect Stoichiometry and Kinetics of Chain Elongating Microbial Communities in Sequencing Batch Bioreactors. Front Bioeng Biotechnol 2021; 9:693030. [PMID: 34235138 PMCID: PMC8256265 DOI: 10.3389/fbioe.2021.693030] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 05/25/2021] [Indexed: 11/13/2022] Open
Abstract
Anaerobic microbial communities can produce carboxylic acids of medium chain length (e.g., caproate, caprylate) by elongating short chain fatty acids through reversed β-oxidation. Ethanol is a common electron donor for this process. The influence of environmental conditions on the stoichiometry and kinetics of ethanol-based chain elongation remains elusive. Here, a sequencing batch bioreactor setup with high-resolution off-gas measurements was used to identify the physiological characteristics of chain elongating microbial communities enriched on acetate and ethanol at pH 7.0 ± 0.2 and 5.5 ± 0.2. Operation at both pH-values led to the development of communities that were highly enriched (>50%, based on 16S rRNA gene amplicon sequencing) in Clostridium kluyveri related species. At both pH-values, stably performing cultures were characterized by incomplete substrate conversion and decreasing biomass-specific hydrogen production rates during an operational cycle. The process stoichiometries obtained at both pH-values were different: at pH 7.0, 71 ± 6% of the consumed electrons were converted to caproate, compared to only 30 ± 5% at pH 5.5. Operating at pH 5.5 led to a decrease in the biomass yield, but a significant increase in the biomass-specific substrate uptake rate, suggesting that the organisms employ catabolic overcapacity to deal with energy losses associated to product inhibition. These results highlight that chain elongating conversions rely on a delicate balance between substrate uptake- and product inhibition kinetics.
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Affiliation(s)
| | | | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, Netherlands
| | - Robbert Kleerebezem
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
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31
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Debabov VG. Acetogens: Biochemistry, Bioenergetics, Genetics, and Biotechnological Potential. Microbiology (Reading) 2021. [DOI: 10.1134/s0026261721030024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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Shanthi Sravan J, Tharak A, Annie Modestra J, Seop Chang I, Venkata Mohan S. Emerging trends in microbial fuel cell diversification-Critical analysis. BIORESOURCE TECHNOLOGY 2021; 326:124676. [PMID: 33556705 DOI: 10.1016/j.biortech.2021.124676] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/30/2020] [Accepted: 01/02/2021] [Indexed: 06/12/2023]
Abstract
Global need for transformation from fossil-based to bio-based economy is constantly emerging for the production of low-carbon/renewable energy/products. Microbial fuel cell (MFC) catalysed by bio-electrochemical process gained significant attention initially for its unique potential to generate energy. Diversification of MFC is an emerging trend in the context of prioritising/enhancing product output while exploring the mechanism specificity of individual processes. Bioelectrochemical treatment system (BET), microbial electrosynthesis system (MES), bioelectrochemical system (BES), electro-fermentation (EF), microbial desalination cell (MDC), microbial electrolysis cell (MEC) and electro-methanogenesis (EM) are the diversified MFC systems that are being researched actively. Owing to its broad diversification, MFC domain is increasing its potential credibility as a platform technology. Microbial catalyzed electrochemical reactions are the key which directly/indirectly are proportionally linked to electrometabolic activity of microorganisms towards final anticipated output. This review intends to holistically document the mechanisms, applications and current trends of MFC diversifications towards multi-faced applications.
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Affiliation(s)
- J Shanthi Sravan
- Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Athmakuri Tharak
- Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500 007, India
| | - J Annie Modestra
- Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - In Seop Chang
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwag-iro, Buk-gu, Gwangju 61005, Republic of Korea
| | - S Venkata Mohan
- Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
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33
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Wu Q, Feng X, Chen Y, Liu M, Bao X. Continuous medium chain carboxylic acids production from excess sludge by granular chain-elongation process. JOURNAL OF HAZARDOUS MATERIALS 2021; 402:123471. [PMID: 32693336 DOI: 10.1016/j.jhazmat.2020.123471] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/22/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Short chain carboxylic acids (SCCAs) production is one of the primary ways to recycle excess sludge (ES). However, the high cost for the SCCAs separation/extraction due to its complete miscibility in water hinders the practical application of SCCAs and the popularization of this recycling way. To overcome this barrier, this study performed an emerging chain elongation (CE) technology to upgrade the SCCAs-rich sludge fermentation broth into the highly hydrophobic medium chain carboxylic acids (MCCAs). In a continuous expanded granule sludge bed (EGSB) reactor, a maximal MCCAs yield of 67.39 % and the corresponding concentration of 9.80 g COD/L (224.97 mM C/L) were achieved. By supplying CO2 at a loading rate of 2 [Formula: see text] to lower the hydrogen partial pressure, the ethanol utilization rate and the resulting MCCAs yield were further improved. In addition, three branched-MCCAs including iso-caproate, iso-heptylate, and iso-caprylate were obtained the first time from waste biomass with the average proportions of 6.17 %, 3.65 %, and 0.8 %, respectively. The branched-MCCAs came from the CE of branched-SCCAs. The granule sludges performing CE were mainly consisted of rod-shaped cells, and dominated by Clostridium sensu stricto and Clostridium IV. This study is expected to lay a foundation for recycling ES to MCCAs.
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Affiliation(s)
- Qinglian Wu
- College of Architecture and Environment, Sichuan University, Chengdu, 610065, China
| | - Xiaochi Feng
- School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong, 518055, China
| | - Ying Chen
- College of Architecture and Environment, Sichuan University, Chengdu, 610065, China
| | - Min Liu
- College of Architecture and Environment, Sichuan University, Chengdu, 610065, China
| | - Xian Bao
- School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
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34
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Ghysels S, Buffel S, Rabaey K, Ronsse F, Ganigué R. Biochar and activated carbon enhance ethanol conversion and selectivity to caproic acid by Clostridium kluyveri. BIORESOURCE TECHNOLOGY 2021; 319:124236. [PMID: 33254460 DOI: 10.1016/j.biortech.2020.124236] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/02/2020] [Accepted: 10/03/2020] [Indexed: 06/12/2023]
Abstract
Syngas from biomass or steel mills can be fermented into a dilute stream of ethanol and acetic acid, which requires energy intensive distillation for product recovery. This can be circumvented by selective secondary fermentation of the syngas fermentation effluent to caproic acid as easier recoverable platform chemical with Clostridium kluyveri. Here, we explore the impact of biochar and activated carbon on this process. Changes during the fermentation with biochar or activated carbon were monitored, different doses were tested and the recyclability of biochar and activated carbon was assessed. Biochar decreased the lag phase and increased the caproic acid production rate (up to 0.50 g·L-1·h-1). Upon recycling for subsequent fermentation, biochar retained this property largely. Activated carbon addition, especially at high dose, could potentially increase the conversion and selectivity towards caproic acid to 14.15 g·L-1 (control: 11.01 g·L-1) and 92% (control: 84%), respectively.
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Affiliation(s)
- Stef Ghysels
- Thermochemical Conversion of Biomass Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure links 653, B-9000 Ghent, Belgium; Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure links 653, B-9000 Ghent, Belgium
| | - Sara Buffel
- Thermochemical Conversion of Biomass Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure links 653, B-9000 Ghent, Belgium; Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure links 653, B-9000 Ghent, Belgium
| | - Korneel Rabaey
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure links 653, B-9000 Ghent, Belgium; Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Belgium
| | - Frederik Ronsse
- Thermochemical Conversion of Biomass Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure links 653, B-9000 Ghent, Belgium
| | - Ramon Ganigué
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure links 653, B-9000 Ghent, Belgium; Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Belgium.
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35
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Katsyv A, Müller V. Overcoming Energetic Barriers in Acetogenic C1 Conversion. Front Bioeng Biotechnol 2020; 8:621166. [PMID: 33425882 PMCID: PMC7793690 DOI: 10.3389/fbioe.2020.621166] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 11/19/2020] [Indexed: 11/13/2022] Open
Abstract
Currently one of the biggest challenges for society is to combat global warming. A solution to this global threat is the implementation of a CO2-based bioeconomy and a H2-based bioenergy economy. Anaerobic lithotrophic bacteria such as the acetogenic bacteria are key players in the global carbon and H2 cycle and thus prime candidates as driving forces in a H2- and CO2-bioeconomy. Naturally, they convert two molecules of CO2via the Wood-Ljungdahl pathway (WLP) to one molecule of acetyl-CoA which can be converted to different C2-products (acetate or ethanol) or elongated to C4 (butyrate) or C5-products (caproate). Since there is no net ATP generation from acetate formation, an electron-transport phosphorylation (ETP) module is hooked up to the WLP. ETP provides the cell with additional ATP, but the ATP gain is very low, only a fraction of an ATP per mol of acetate. Since acetogens live at the thermodynamic edge of life, metabolic engineering to obtain high-value products is currently limited by the low energy status of the cells that allows for the production of only a few compounds with rather low specificity. To set the stage for acetogens as production platforms for a wide range of bioproducts from CO2, the energetic barriers have to be overcome. This review summarizes the pathway, the energetics of the pathway and describes ways to overcome energetic barriers in acetogenic C1 conversion.
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Affiliation(s)
- Alexander Katsyv
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
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Cui Y, Yang KL, Zhou K. Using Co-Culture to Functionalize Clostridium Fermentation. Trends Biotechnol 2020; 39:914-926. [PMID: 33342558 DOI: 10.1016/j.tibtech.2020.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 11/22/2020] [Accepted: 11/25/2020] [Indexed: 01/23/2023]
Abstract
Clostridium fermentations have been developed for producing butanol and other value-added chemicals, but their development is constrained by some limitations, such as relatively high substrate cost and the need to maintain an anaerobic condition. Recently, co-culture is emerging as a popular way to address these limitations by introducing a partner strain with Clostridium. Generally speaking, the co-culture strategy enables the use of a cheaper substrate, maintains the growth of Clostridium without any anaerobic treatment, improves product yields, and/or widens the product spectrum. Herein, we review recent developments of co-culture strategies involving Clostridium species according to their partner stains' functions with representative examples. We also discuss research challenges that need to be addressed for the future development of Clostridium co-cultures.
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Affiliation(s)
- Yonghao Cui
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore
| | - Kun-Lin Yang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore.
| | - Kang Zhou
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore.
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37
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Fermentation of Organic Residues to Beneficial Chemicals: A Review of Medium-Chain Fatty Acid Production. Processes (Basel) 2020. [DOI: 10.3390/pr8121571] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Medium-chain fatty acids (MCFAs) have a variety of uses in the production of industrial chemicals, food, and personal care products. These compounds are often produced through palm refining, but recent work has demonstrated that MCFAs can also be produced through the fermentation of complex organic substrates, including organic waste streams. While “chain elongation” offers a renewable platform for producing MCFAs, there are several limitations that need to be addressed before full-scale implementation becomes widespread. Here, we review the history of work on MCFA production by both pure and mixed cultures of fermenting organisms, and the unique metabolic features that lead to MCFA production. We also offer approaches to address the remaining challenges and increase MCFA production from renewable feedstocks.
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38
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Kutscha R, Pflügl S. Microbial Upgrading of Acetate into Value-Added Products-Examining Microbial Diversity, Bioenergetic Constraints and Metabolic Engineering Approaches. Int J Mol Sci 2020; 21:ijms21228777. [PMID: 33233586 PMCID: PMC7699770 DOI: 10.3390/ijms21228777] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 10/29/2020] [Accepted: 11/18/2020] [Indexed: 01/20/2023] Open
Abstract
Ecological concerns have recently led to the increasing trend to upgrade carbon contained in waste streams into valuable chemicals. One of these components is acetate. Its microbial upgrading is possible in various species, with Escherichia coli being the best-studied. Several chemicals derived from acetate have already been successfully produced in E. coli on a laboratory scale, including acetone, itaconic acid, mevalonate, and tyrosine. As acetate is a carbon source with a low energy content compared to glucose or glycerol, energy- and redox-balancing plays an important role in acetate-based growth and production. In addition to the energetic challenges, acetate has an inhibitory effect on microorganisms, reducing growth rates, and limiting product concentrations. Moreover, extensive metabolic engineering is necessary to obtain a broad range of acetate-based products. In this review, we illustrate some of the necessary energetic considerations to establish robust production processes by presenting calculations of maximum theoretical product and carbon yields. Moreover, different strategies to deal with energetic and metabolic challenges are presented. Finally, we summarize ways to alleviate acetate toxicity and give an overview of process engineering measures that enable sustainable acetate-based production of value-added chemicals.
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39
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Köpke M, Simpson SD. Pollution to products: recycling of ‘above ground’ carbon by gas fermentation. Curr Opin Biotechnol 2020; 65:180-189. [DOI: 10.1016/j.copbio.2020.02.017] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/21/2020] [Accepted: 02/26/2020] [Indexed: 02/01/2023]
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Vees CA, Neuendorf CS, Pflügl S. Towards continuous industrial bioprocessing with solventogenic and acetogenic clostridia: challenges, progress and perspectives. J Ind Microbiol Biotechnol 2020; 47:753-787. [PMID: 32894379 PMCID: PMC7658081 DOI: 10.1007/s10295-020-02296-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/20/2020] [Indexed: 12/11/2022]
Abstract
The sustainable production of solvents from above ground carbon is highly desired. Several clostridia naturally produce solvents and use a variety of renewable and waste-derived substrates such as lignocellulosic biomass and gas mixtures containing H2/CO2 or CO. To enable economically viable production of solvents and biofuels such as ethanol and butanol, the high productivity of continuous bioprocesses is needed. While the first industrial-scale gas fermentation facility operates continuously, the acetone-butanol-ethanol (ABE) fermentation is traditionally operated in batch mode. This review highlights the benefits of continuous bioprocessing for solvent production and underlines the progress made towards its establishment. Based on metabolic capabilities of solvent producing clostridia, we discuss recent advances in systems-level understanding and genome engineering. On the process side, we focus on innovative fermentation methods and integrated product recovery to overcome the limitations of the classical one-stage chemostat and give an overview of the current industrial bioproduction of solvents.
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Affiliation(s)
- Charlotte Anne Vees
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria
| | - Christian Simon Neuendorf
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria
| | - Stefan Pflügl
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria
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Abstract
Electro-fermentation (EF) is an upcoming technology that can control the metabolism of exoelectrogenic bacteria (i.e., bacteria that transfer electrons using an extracellular mechanism). The fermenter consists of electrodes that act as sink and source for the production and movement of electrons and protons, thus generating electricity and producing valuable products. The conventional process of fermentation has several drawbacks that restrict their application and economic viability. Additionally, metabolic reactions taking place in traditional fermenters are often redox imbalanced. Almost all metabolic pathways and microbial strains have been studied, and EF can electrochemically control this. The process of EF can be used to optimize metabolic processes taking place in the fermenter by controlling the redox and pH imbalances and by stimulating carbon chain elongation or breakdown to improve the overall biomass yield and support the production of a specific product. This review briefly discusses microbe-electrode interactions, electro-fermenter designs, mixed-culture EF, and pure culture EF in industrial applications, electro methanogenesis, and the various products that could be hence generated using this process.
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Venkateswar Reddy M, Kumar G, Mohanakrishna G, Shobana S, Al-Raoush RI. Review on the production of medium and small chain fatty acids through waste valorization and CO 2 fixation. BIORESOURCE TECHNOLOGY 2020; 309:123400. [PMID: 32371319 DOI: 10.1016/j.biortech.2020.123400] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 06/11/2023]
Abstract
The developing approaches in the recovery of resources from biowastes for the production of renewable value-added products and fuels, using microbial cultures as bio-catalyst have now became promising aspect. In the path of anaerobic digestion, the microorganisms are assisting transformation of a complex organic feedstock/waste to biomass and biogas. This potentiality consequently leads to the production of intermediate precursors of renewable value-added products. Particularly, a set of anaerobic pathways in the fermentation process, yields small-chain fatty acids (SCFA), and medium-chain fatty acids (MCFA) via chain elongation pathways from waste valorization and CO2 fixation. This review focuses on the production of SCFA and MCFA from CO2, synthetic substrates and waste materials. Moreover, the review introduces the metabolic engineering of Escherichia coli and Saccharomyces cerevisiae for SCFAs/MCFAs production. Furtherly, it concludes that future critical research might target progress of this promising approach as a valorization of complex organic wastes.
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Affiliation(s)
- M Venkateswar Reddy
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms Universität, Corrensstr. 3, 48149 Münster, Germany
| | - Gopalakrishnan Kumar
- School of Civil and Environmental Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Gunda Mohanakrishna
- Department of Civil and Architectural Engineering, College of Engineering, Qatar University, P O Box 2713, Doha, Qatar.
| | - Sutha Shobana
- Department of Chemistry & Research Centre, Mohamed Sathak Engineering College, Kilakarai, 623 806 Ramanathapuram, Tamil Nadu, India
| | - Riyadh I Al-Raoush
- Department of Civil and Architectural Engineering, College of Engineering, Qatar University, P O Box 2713, Doha, Qatar
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Zhang W, Yin F, Dong H, Cao Q, Wang S, Xu J, Zhu Z. Bioconversion of swine manure into high-value products of medium chain fatty acids. WASTE MANAGEMENT (NEW YORK, N.Y.) 2020; 113:478-487. [PMID: 32615515 DOI: 10.1016/j.wasman.2020.06.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 06/15/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
This research proposes and demonstrates, for the first time, the utilization of swine manure as a complex feedstock to produce high-value medium chain fatty acids (MCFA). The two-stage anaerobic digestion (AD) carboxylates platform was adopted for the conversion of swine manure to short chain fatty acids (SCFAs) and then SCFAs to MCFA (n-caproate, n-heptanoate, and n-caprylate) with ethanol supplementation. We defined the appropriate initial pH of 10.0 for SCFAs production with a carbon conversion rate of 71.2%, and acetate, propionate were the main products, which accounted for around 72.9% of the total SCFAs in the primary stage (I). Through the addition of ethanol, 61.3% of the converted carbon in the complex SCFAs solution was converted into MCFA (C6-C8) in the chain elongation stage (II), while only 6.7% was attributed to methane formation. The concentrations of n-caproate, n-heptanoate, and n-caprylate reached 8.6 g COD/L (3.9 g/L), 6.4 g COD/L (2.7 g/L), and 2.6 g COD/L (1.07 g/L), respectively. This study achieved a relatively higher concentration of n-heptanoate compared with past studies of MCFA from other feedstock. These findings demonstrated a new route for resource recovery and the operating parameters for producing MCFA from swine manure.
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Affiliation(s)
- Wanqin Zhang
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Key Laboratory of Energy Conservation and Waste Treatment of Agricultural Structures, Ministry of Agriculture, Beijing 100081, China
| | - Fubin Yin
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Key Laboratory of Energy Conservation and Waste Treatment of Agricultural Structures, Ministry of Agriculture, Beijing 100081, China
| | - Hongmin Dong
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Key Laboratory of Energy Conservation and Waste Treatment of Agricultural Structures, Ministry of Agriculture, Beijing 100081, China.
| | - Qitao Cao
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Key Laboratory of Energy Conservation and Waste Treatment of Agricultural Structures, Ministry of Agriculture, Beijing 100081, China
| | - Shunli Wang
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Key Laboratory of Energy Conservation and Waste Treatment of Agricultural Structures, Ministry of Agriculture, Beijing 100081, China
| | - Jiajie Xu
- Biological and Environmental Sciences and Engineering Division, Water Desalination and Reuse Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Zhiping Zhu
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Key Laboratory of Energy Conservation and Waste Treatment of Agricultural Structures, Ministry of Agriculture, Beijing 100081, China
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Pan XR, Huang L, Fu XZ, Yuan YR, Liu HQ, Li WW, Yu L, Zhao QB, Zuo J, Chen L, Lam PKS. Long-term, selective production of caproate in an anaerobic membrane bioreactor. BIORESOURCE TECHNOLOGY 2020; 302:122865. [PMID: 32004814 DOI: 10.1016/j.biortech.2020.122865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/16/2020] [Accepted: 01/21/2020] [Indexed: 06/10/2023]
Abstract
Fermentative caproate production from wastewater is attractive but is currently limited by the low product purity and concentration. In this work, continuous, selective production of caproate from acetate and ethanol, the common products of wastewater anaerobic fermentation, was achieved in an anaerobic membrane bioreactor (AnMBR). The reactor was continuously operated for over 522 days without need for chemical cleaning. With an ethanol-to-acetate ratio of 3.0, the effluent caproate concentration was 2.62 g/L on average and the caproate ratio in liquid products reached 74%. Further raising the influent ethanol content slightly increased the effluent caproate level but lowered the product selectivity and resulted in microbial inhibition. The Clostridia (the major caproate-producing bacteria) and Methanobacterium species (which consume hydrogen to alleviate microbial inhibition) was significantly enriched in the acclimated sludge. Our results imply a great potential of utilizing AnMBR to recover caproate from the effluent of wastewater acidogenic fermentation process.
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Affiliation(s)
- Xin-Rong Pan
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China; Department of Chemistry, City University of Hong Kong, Hong Kong SAR 999077, China; State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Liang Huang
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Xian-Zhong Fu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yan-Ru Yuan
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Hou-Qi Liu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Wen-Wei Li
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
| | - Lei Yu
- Department of Environmental Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Quan-Bao Zhao
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Jiane Zuo
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Lei Chen
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Paul Kwan-Sing Lam
- Department of Chemistry, City University of Hong Kong, Hong Kong SAR 999077, China
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45
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San-Valero P, Abubackar HN, Veiga MC, Kennes C. Effect of pH, yeast extract and inorganic carbon on chain elongation for hexanoic acid production. BIORESOURCE TECHNOLOGY 2020; 300:122659. [PMID: 31893537 DOI: 10.1016/j.biortech.2019.122659] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 12/17/2019] [Accepted: 12/18/2019] [Indexed: 06/10/2023]
Abstract
Several anaerobic bioconversion technologies produce short chain volatile fatty acids and sometimes ethanol, which can together be elongated to hexanoic acid (C6 acid) by Clostridium kluyveri in a secondary fermentation process. Initiatives are needed to further optimize the process. Therefore, five strategies were tested aiming at elucidating their influence on hexanoic acid production from mixtures of acetic acid, butyric acid and ethanol. pH-regulated bioreactors, maintained at pH 7.5, 6.8 or 6.4 led to maximum C6 acid concentrations of, respectively, 19.4, 18.3 and 13.3 g L-1. At pH 6.8, yeast extract omission resulted in a decrease of the hexanoic acid concentration to 12.0 g L-1 while the addition of an inorganic carbon source, such as bicarbonate, for pH control, increased the C6 acid concentration up to 21.4 g L-1. This research provides guidelines for efficient improved production of hexanoic acid by pure cultures of C. kluyveri, contributing to the state of art.
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Affiliation(s)
- Pau San-Valero
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), University of La Coruña, Rúa da Fraga 10, E - 15008 La Coruña, Spain
| | - Haris Nalakath Abubackar
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), University of La Coruña, Rúa da Fraga 10, E - 15008 La Coruña, Spain
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), University of La Coruña, Rúa da Fraga 10, E - 15008 La Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), University of La Coruña, Rúa da Fraga 10, E - 15008 La Coruña, Spain.
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46
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Enrichment and characterisation of ethanol chain elongating communities from natural and engineered environments. Sci Rep 2020; 10:3682. [PMID: 32111851 PMCID: PMC7048776 DOI: 10.1038/s41598-020-60052-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 02/03/2020] [Indexed: 01/13/2023] Open
Abstract
Chain elongation is a microbial process in which an electron donor, such as ethanol, is used to elongate short chain carboxylic acids, such as acetic acid, to medium chain carboxylic acids. This metabolism has been extensively investigated, but the spread and differentiation of chain elongators in the environment remains unexplored. Here, chain elongating communities were enriched from several inocula (3 anaerobic digesters, 2 animal faeces and 1 caproic acid producing environment) using ethanol and acetic acid as substrates at pH 7 and 5.5. This approach showed that (i) the inoculum’s origin determines the pH where native chain elongators can grow; (ii) pH affects caproic acid production, with average caproic acid concentrations of 6.4 ± 1.6 g·L−1 at pH 7, versus 2.3 ± 1.8 g·L−1 at pH 5.5; however (iii) pH does not affect growth rates significantly; (iv) all communities contained a close relative of the known chain elongator Clostridium kluyveri; and (v) low pH selects for communities more enriched in this Clostridium kluyveri-relative (57.6 ± 23.2% at pH 7, 96.9 ± 1.2% at pH 5.5). These observations show that ethanol-consuming chain elongators can be found in several natural and engineered environments, but are not the same everywhere, emphasising the need for careful inoculum selection during process development.
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47
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LaBelle EV, Marshall CW, May HD. Microbiome for the Electrosynthesis of Chemicals from Carbon Dioxide. Acc Chem Res 2020; 53:62-71. [PMID: 31809012 DOI: 10.1021/acs.accounts.9b00522] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The price for renewable electricity is rapidly decreasing, and the availability of such energy is expected to increase in the coming years. This is a welcomed outcome considering that mitigation of climate disruption due to the use of fossil carbon is reaching a critical stage. However, the economy will remain dependent on carbon-based chemicals and the problem of electricity storage persists. Therefore, the development of electrosynthetic processes that convert electricity and CO2 into chemicals and energy dense fuels, perhaps even food, would be desirable. Electrochemistry has been applied to the manufacture of many valuable products and at a large industrial scale, but it is difficult to produce multicarbon chemicals from CO2 by chemistry alone. Being that the biological world possesses expertise at the construction of C-C bonds, it is being examined in conjunction with electrochemistry to discover new ways of synthesizing chemicals from electricity and CO2. One approach is microbial electrosynthesis. This Account describes the development of a microbial electrosynthesis system by the authors. A biocathode consisting of a carbon-based electrode and a microbial community produced short chain fatty acids, primarily acetate. The device works by electrolysis of water, but microbes facilitate electron transfer from the cathode while reducing CO2 by the Wood-Ljungdahl pathway possessed by an Acetobacterium sp. While this acetogenic microorganism dominates the microbiome growing on the cathode surface, 13 total species of microbes overall were ecologically selected on the cathode and genomes for each have been assembled. The combined species may contribute to the stability of the microbiome, a common feature of naturally selected microbial communities. The microbial electrosynthesis system was demonstrated to operate continuously at a cathode for more than 2 years and could also be used with intermittent power, thus demonstrating the stability of the microbiome living at the cathode. In addition to the description of reactor design and startup procedures, the possible mechanisms of electron transfer are described in this Account. While mysteries remain to be solved, much evidence indicates that the microbiome may facilitate electron transfer by supplying catalyst(s) external to the bacterial cells and onto the cathode surface. This may be in the form of a hydrogen-producing catalyst that enhances hydrogen generation by an inert carbon-based electrode. Through the enrichment of the electrosynthetic microbiome along with several modifications in reactor design and operation, the productivity and efficiency were improved. In addition to the intrinsic value of the current products, coupling the process with a secondary stage might be used to produce more valuable products from the acetic acid stream such as lipids, biocrude oil, or higher value food supplements. Alternatively, additional work on the mechanism of electron transfer, reactor design/operation, and modification of the microbes through synthetic biology, particularly to enhance carbon efficiency into higher value chemicals, are the needed next steps to advance microbial electrosynthesis so that it may be used to transform renewable electrons and CO2 directly into products and help solve the problem of climate disruption.
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Affiliation(s)
- Edward V. LaBelle
- Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Christopher W. Marshall
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - Harold D. May
- Department of Microbiology & Immunology, Hollings Marine Laboratory, Medical University of South Carolina, Charleston, South Carolina 29412, United States
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Han W, He P, Shao L, Lü F. Road to full bioconversion of biowaste to biochemicals centering on chain elongation: A mini review. J Environ Sci (China) 2019; 86:50-64. [PMID: 31787190 DOI: 10.1016/j.jes.2019.05.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Revised: 05/16/2019] [Accepted: 05/16/2019] [Indexed: 06/10/2023]
Abstract
Production of biochemicals from waste streams has been attracting increasing worldwide interest to achieve climate protection goals. Chain elongation (CE) for production of medium-chain carboxylic acids (MCCAs, especially caproate, enanthate and caprylate) from diverse biowaste has emerged as a potential economic and environmental technology for a sustainable society. The present mini review summarizes the research utilizing various synthetic or real waste-derived substrates available for MCCA production. Additionally, the microbial characteristics of the CE process are surveyed and discussed. Considering that a large proportion of recalcitrantly biodegradable biowaste and residues cannot be further utilized by CE systems and remain to be treated and disposed, we propose here a loop concept of bioconversion of biowaste to MCCAs making full use of the biowaste with zero emission. This could make possible an alternative technology for synthesis of value-added products from a wide range of biowaste, or even non-biodegradable waste (such as, plastics and rubbers). Meanwhile, the remaining scientific questions, unsolved problems, application potential and possible developments for this technology are discussed.
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Affiliation(s)
- Wenhao Han
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Pinjing He
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China; Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China; Centre for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban-Rural Development of China (MOHURD), China
| | - Liming Shao
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China; Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China; Centre for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban-Rural Development of China (MOHURD), China
| | - Fan Lü
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China; Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China.
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Syngas-aided anaerobic fermentation for medium-chain carboxylate and alcohol production: the case for microbial communities. Appl Microbiol Biotechnol 2019; 103:8689-8709. [PMID: 31612269 DOI: 10.1007/s00253-019-10086-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/06/2019] [Accepted: 08/07/2019] [Indexed: 01/01/2023]
Abstract
Syngas fermentation has been successfully implemented in commercial-scale plants and can enable the biochemical conversion of the driest fractions of biomass through synthesis gas (H2, CO2, and CO). The process relies on optimized acetogenic strains able to reach and maintain high productivity of ethanol and acetate. In parallel, microbial communities have shown to be the best choice for the production of valuable medium-chain carboxylates through anaerobic fermentation of biomass, demanding low technical complexity and being able to realize simultaneous hydrolysis of the substrate. Each of the two technologies benefits from different strong points and has different challenges to overcome. This review discusses the rationales for merging these two seemingly disparate technologies by analyzing previous studies and drawing opinions based on the lessons learned from such studies. For keeping the technical demands of the resulting process low, a case is built for using microbial communities instead of pure strains. For that to occur, a shift from conventional syngas-based to "syngas-aided" anaerobic fermentation is suggested. Strategies for tackling the intricacies of working simultaneously with communities and syngas, such as competing pathways, and thermodynamic aspects are discussed as well as the stoichiometry and economic feasibility of the concept. Overall, syngas-aided anaerobic fermentation seems to be a promising concept for the biorefinery of the future. However, the effects of process parameters on microbial interactions have to be understood in greater detail, in order to achieve and sustain feasible medium-chain carboxylate and alcohol productivity.
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50
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Sun X, Atiyeh HK, Huhnke RL, Tanner RS. Syngas fermentation process development for production of biofuels and chemicals: A review. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.biteb.2019.100279] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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