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Nawab S, Zhang Y, Ullah MW, Lodhi AF, Shah SB, Rahman MU, Yong YC. Microbial host engineering for sustainable isobutanol production from renewable resources. Appl Microbiol Biotechnol 2024; 108:33. [PMID: 38175234 DOI: 10.1007/s00253-023-12821-9] [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: 09/10/2023] [Revised: 12/10/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024]
Abstract
Due to the limited resources and environmental problems associated with fossil fuels, there is a growing interest in utilizing renewable resources for the production of biofuels through microbial fermentation. Isobutanol is a promising biofuel that could potentially replace gasoline. However, its production efficiency is currently limited by the use of naturally isolated microorganisms. These naturally isolated microorganisms often encounter problems such as a limited range of substrates, low tolerance to solvents or inhibitors, feedback inhibition, and an imbalanced redox state. This makes it difficult to improve their production efficiency through traditional process optimization methods. Fortunately, recent advancements in genetic engineering technologies have made it possible to enhance microbial hosts for the increased production of isobutanol from renewable resources. This review provides a summary of the strategies and synthetic biology approaches that have been employed in the past few years to improve naturally isolated or non-natural microbial hosts for the enhanced production of isobutanol by utilizing different renewable resources. Furthermore, it also discusses the challenges that are faced by engineered microbial hosts and presents future perspectives to enhancing isobutanol production. KEY POINTS: • Promising potential of isobutanol to replace gasoline • Engineering of native and non-native microbial host for isobutanol production • Challenges and opportunities for enhanced isobutanol production.
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Affiliation(s)
- Said Nawab
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - YaFei Zhang
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Muhammad Wajid Ullah
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Adil Farooq Lodhi
- Department of Microbiology, Faculty of Biological and Health Sciences, Hazara University, Mansehra, Pakistan
| | - Syed Bilal Shah
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Mujeeb Ur Rahman
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Yang-Chun Yong
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China.
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Ponsetto P, Sasal EM, Mazzoli R, Valetti F, Gilardi G. The potential of native and engineered Clostridia for biomass biorefining. Front Bioeng Biotechnol 2024; 12:1423935. [PMID: 39219620 PMCID: PMC11365079 DOI: 10.3389/fbioe.2024.1423935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 08/06/2024] [Indexed: 09/04/2024] Open
Abstract
Since their first industrial application in the acetone-butanol-ethanol (ABE) fermentation in the early 1900s, Clostridia have found large application in biomass biorefining. Overall, their fermentation products include organic acids (e.g., acetate, butyrate, lactate), short chain alcohols (e.g., ethanol, n-butanol, isobutanol), diols (e.g., 1,2-propanediol, 1,3-propanediol) and H2 which have several applications such as fuels, building block chemicals, solvents, food and cosmetic additives. Advantageously, several clostridial strains are able to use cheap feedstocks such as lignocellulosic biomass, food waste, glycerol or C1-gases (CO2, CO) which confer them additional potential as key players for the development of processes less dependent from fossil fuels and with reduced greenhouse gas emissions. The present review aims to provide a survey of research progress aimed at developing Clostridium-mediated biomass fermentation processes, especially as regards strain improvement by metabolic engineering.
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Affiliation(s)
| | | | - Roberto Mazzoli
- Structural and Functional Biochemistry, Laboratory of Proteomics and Metabolic Engineering of Prokaryotes, Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
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Tian Y, Rimal B, Bisanz JE, Gui W, Wolfe TM, Koo I, Murray IA, Nettleford SK, Yokoyama S, Dong F, Koshkin S, Prabhu KS, Turnbaugh PJ, Walk ST, Perdew GH, Patterson AD. Effects of Early Life Exposures to the Aryl Hydrocarbon Receptor Ligand TCDF on Gut Microbiota and Host Metabolic Homeostasis in C57BL/6J Mice. ENVIRONMENTAL HEALTH PERSPECTIVES 2024; 132:87005. [PMID: 39140734 PMCID: PMC11323762 DOI: 10.1289/ehp13356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 04/30/2024] [Accepted: 07/08/2024] [Indexed: 08/15/2024]
Abstract
BACKGROUND Exposure to persistent organic pollutants (POPs) and disruptions in the gastrointestinal microbiota have been positively correlated with a predisposition to factors such as obesity, metabolic syndrome, and type 2 diabetes; however, it is unclear how the microbiome contributes to this relationship. OBJECTIVE This study aimed to explore the association between early life exposure to a potent aryl hydrocarbon receptor (AHR) agonist and persistent disruptions in the microbiota, leading to impaired metabolic homeostasis later in life. METHODS This study used metagenomics, nuclear magnetic resonance (NMR)- and mass spectrometry (MS)-based metabolomics, and biochemical assays to analyze the gut microbiome composition and function, as well as the physiological and metabolic effects of early life exposure to 2,3,7,8-tetrachlorodibenzofuran (TCDF) in conventional, germ-free (GF), and Ahr-null mice. The impact of TCDF on Akkermansia muciniphila (A. muciniphila) in vitro was assessed using optical density (OD 600), flow cytometry, transcriptomics, and MS-based metabolomics. RESULTS TCDF-exposed mice exhibited lower abundances of A. muciniphila, lower levels of cecal short-chain fatty acids (SCFAs) and indole-3-lactic acid (ILA), as well as lower levels of the gut hormones glucagon-like peptide 1 (GLP-1) and peptide YY (PYY), findings suggestive of disruption in the gut microbiome community structure and function. Importantly, microbial and metabolic phenotypes associated with early life POP exposure were transferable to GF recipients in the absence of POP carry-over. In addition, AHR-independent interactions between POPs and the microbiota were observed, and they were significantly associated with growth, physiology, gene expression, and metabolic activity outcomes of A. muciniphila, supporting suppressed activity along the ILA pathway. CONCLUSIONS These data obtained in a mouse model point to the complex effects of POPs on the host and microbiota, providing strong evidence that early life, short-term, and self-limiting POP exposure can adversely impact the microbiome, with effects persisting into later life with associated health implications. https://doi.org/10.1289/EHP13356.
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Affiliation(s)
- Yuan Tian
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
- Huck Institutes of the Life Sciences, Penn State, University Park, Pennsylvania, USA
| | - Bipin Rimal
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
| | - Jordan E. Bisanz
- Department of Biochemistry and Molecular Biology, Penn State, University Park, Pennsylvania, USA
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, USA
| | - Wei Gui
- Huck Institutes of the Life Sciences, Penn State, University Park, Pennsylvania, USA
| | - Trenton M. Wolfe
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, Montana, USA
| | - Imhoi Koo
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
| | - Iain A. Murray
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
| | - Shaneice K. Nettleford
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
| | - Shigetoshi Yokoyama
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
| | - Fangcong Dong
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
| | - Sergei Koshkin
- Huck Institutes of the Life Sciences, Penn State, University Park, Pennsylvania, USA
| | - K. Sandeep Prabhu
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
| | - Peter J. Turnbaugh
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, USA
- Chan Zuckerberg Biohub–San Francisco, San Francisco, California, USA
| | - Seth T. Walk
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, Montana, USA
| | - Gary H. Perdew
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
| | - Andrew D. Patterson
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University (Penn State), University Park, Pennsylvania, USA
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Shipmon JC, Rathinasabapathi P, Broich ML, Hemansi, Eiteman MA. Production of Esters in Escherichia coli Using Citrate Synthase Variants. Microorganisms 2024; 12:1338. [PMID: 39065106 PMCID: PMC11278746 DOI: 10.3390/microorganisms12071338] [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: 06/03/2024] [Revised: 06/24/2024] [Accepted: 06/27/2024] [Indexed: 07/28/2024] Open
Abstract
Acetate esters comprise a wide range of products including fragrances and industrial solvents. Biosynthesis of esters offers a promising alternative to chemical synthesis because such routes use renewable carbohydrate resources and minimize the generation of waste. One biochemical method for ester formation relies on the ATF1 gene from Saccharomyces cerevisiae, which encodes alcohol-O-acyltransferase (AAT) which converts acetyl-CoA and an exogenously supplied alcohol into the ester. In this study, the formation of several acetate esters via AAT was examined in Escherichia coli chromosomally expressing citrate synthase variants, which create a metabolic bottleneck at acetyl-CoA. In shake flask cultures, variant strains generated more acetate esters than the strains expressing the wild-type citrate synthase. In a controlled bioreactor, E. coli GltA[A267T] generated 3.9 g propyl acetate in 13 h, corresponding to a yield of 0.155 g propyl acetate/g glucose, which is 18% greater than that obtained by the wild-type GltA control. These results demonstrate the ability of citrate synthase variants to redistribute carbon from central metabolism into acetyl-CoA-derived biochemicals.
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Affiliation(s)
- Jacoby C. Shipmon
- School of Chemical, Materials and Biomedical Engineering, University of Georgia, Athens, GA 30602, USA; (J.C.S.)
| | - Pasupathi Rathinasabapathi
- School of Chemical, Materials and Biomedical Engineering, University of Georgia, Athens, GA 30602, USA; (J.C.S.)
- Department of Genetic Engineering, SRM Institute of Science and Technology, Chengalpattu District, Kattankulathur 603202, Tamil Nadu, India
| | - Michael L. Broich
- School of Chemical, Materials and Biomedical Engineering, University of Georgia, Athens, GA 30602, USA; (J.C.S.)
| | - Hemansi
- School of Chemical, Materials and Biomedical Engineering, University of Georgia, Athens, GA 30602, USA; (J.C.S.)
- Department of Microbiology, Central University of Haryana, Mahendergarh 123029, Haryana, India
| | - Mark A. Eiteman
- School of Chemical, Materials and Biomedical Engineering, University of Georgia, Athens, GA 30602, USA; (J.C.S.)
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Zhao W, Jiang H, Dong W, Liang Q, Yan B, Zhang Y. Elevated caproic acid production from one-stage anaerobic fermentation of organic waste and its selective recovery by electro-membrane process. BIORESOURCE TECHNOLOGY 2024; 399:130647. [PMID: 38561152 DOI: 10.1016/j.biortech.2024.130647] [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: 01/15/2024] [Revised: 03/27/2024] [Accepted: 03/29/2024] [Indexed: 04/04/2024]
Abstract
A constructed microbial consortia-based strategy to enhance caproic acid production from one-stage mixed-fermentation of glucose was developed, which incubated with acidogens (Clostridium sensu stricto 1, 11 dominated) and chain elongators (including Clostridium sensu stricto 12, Sporanaerobacter, and Caproiciproducens) acclimated from anaerobic sludge. Significant product upgrading toward caproic acid (8.31 g‧L-1) and improved substrate degradation was achieved, which can be greatly attributed to the lactic acid platform. Whereas, a small amount of caproic acid was observed in the control incubating with acidogens, with an average concentration of 2.09 g‧L-1. The strategy accelerated the shape and cooperation of the specific microbial community dominated by Clostridium sensu stricto and Caproiciproducens, which thereby contributed to caproic acid production via the fatty acid biosynthesis pathway. Moreover, the tailored electrodialysis with bipolar membrane enabled progressive up-concentration and acidification, allowing selective separation of caproic acid as an immiscible product with a purity of 82.58 % from the mixture.
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Affiliation(s)
- Wenyan Zhao
- College of Environment and Ecology, Hunan Agricultural University, No. 1 Nongda Road, Changsha 410128, China; Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Laoshan District, Qingdao 266101, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Heqing Jiang
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Laoshan District, Qingdao 266101, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Wenjian Dong
- College of Environment and Ecology, Hunan Agricultural University, No. 1 Nongda Road, Changsha 410128, China
| | - Qiaochu Liang
- College of Environment and Safety Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China
| | - Binghua Yan
- College of Environment and Ecology, Hunan Agricultural University, No. 1 Nongda Road, Changsha 410128, China.
| | - Yang Zhang
- College of Environment and Safety Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China
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Meliawati M, Volke DC, Nikel PI, Schmid J. Engineering the carbon and redox metabolism of Paenibacillus polymyxa for efficient isobutanol production. Microb Biotechnol 2024; 17:e14438. [PMID: 38529712 DOI: 10.1111/1751-7915.14438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 02/15/2024] [Accepted: 02/21/2024] [Indexed: 03/27/2024] Open
Abstract
Paenibacillus polymyxa is a non-pathogenic, Gram-positive bacterium endowed with a rich and versatile metabolism. However interesting, this bacterium has been seldom used for bioproduction thus far. In this study, we engineered P. polymyxa for isobutanol production, a relevant bulk chemical and next-generation biofuel. A CRISPR-Cas9-based genome editing tool facilitated the chromosomal integration of a synthetic operon to establish isobutanol production. The 2,3-butanediol biosynthesis pathway, leading to the main fermentation product of P. polymyxa, was eliminated. A mutant strain harbouring the synthetic isobutanol operon (kdcA from Lactococcus lactis, and the native ilvC, ilvD and adh genes) produced 1 g L-1 isobutanol under microaerobic conditions. Improving NADPH regeneration by overexpression of the malic enzyme subsequently increased the product titre by 50%. Network-wide proteomics provided insights into responses of P. polymyxa to isobutanol and revealed a significant metabolic shift caused by alcohol production. Glucose-6-phosphate 1-dehydrogenase, the key enzyme in the pentose phosphate pathway, was identified as a bottleneck that hindered efficient NADPH regeneration through this pathway. Furthermore, we conducted culture optimization towards cultivating P. polymyxa in a synthetic minimal medium. We identified biotin (B7), pantothenate (B5) and folate (B9) to be mutual essential vitamins for P. polymyxa. Our rational metabolic engineering of P. polymyxa for the production of a heterologous chemical sheds light on the metabolism of this bacterium towards further biotechnological exploitation.
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Affiliation(s)
- Meliawati Meliawati
- Institute of Molecular Microbiology and Biotechnology, University of Münster, Münster, Germany
| | - Daniel C Volke
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Jochen Schmid
- Institute of Molecular Microbiology and Biotechnology, University of Münster, Münster, Germany
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Su Y, Mangus AM, Cordell WT, Pfleger BF. Overcoming barriers to medium-chain fatty alcohol production. Curr Opin Biotechnol 2024; 85:103063. [PMID: 38219523 PMCID: PMC10922944 DOI: 10.1016/j.copbio.2023.103063] [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: 11/28/2023] [Revised: 12/19/2023] [Accepted: 12/20/2023] [Indexed: 01/16/2024]
Abstract
Medium-chain fatty alcohols (mcFaOHs) are aliphatic primary alcohols containing six to twelve carbons that are widely used in materials, pharmaceuticals, and cosmetics. Microbial biosynthesis has been touted as a route to less-abundant chain-length molecules and as a sustainable alternative to current petrochemical processes. Several metabolic engineering strategies for producing mcFaOHs have been demonstrated in the literature, yet processes continue to suffer from poor selectivity and mcFaOH toxicity, leading to reduced titers, rates, and yields of the desired compounds. This opinion examines the current state of microbial mcFaOH biosynthesis, summarizing engineering efforts to tailor selectivity and improve product tolerance by implementing engineering strategies that circumvent or overcome mcFaOH toxicity.
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Affiliation(s)
- Yun Su
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Anna M Mangus
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - William T Cordell
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Brian F Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Etit D, Ögmundarson Ó, Zhang J, Krogh Jensen M, Sukumara S. Early-stage economic and environmental impact assessment for optimized bioprocess development: Monoterpenoid indole alkaloids. BIORESOURCE TECHNOLOGY 2024; 391:130005. [PMID: 37952588 DOI: 10.1016/j.biortech.2023.130005] [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: 10/08/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/14/2023]
Abstract
Microbial refactoring offers sustainable production of plant-sourced pharmaceuticals associated with high production costs, ecological harms, and supply chain dependencies. Here, microbial tabersonine production in Saccharomyces cerevisiae is modeled during early-stage development (TRL: 3-5), guiding decisions for process-scale economic and environmental optimization. The base-case 0.7 mg/L titer indicated a minimum selling price (MSP) of $3,910,000/kg and global warming potential (GWP) of 2,540 kgCO2eq/g. The industrial process at 1 g/L resulted in an MSP of 4,262 $/kg and a GWP of 6.36 kgCO2eq/g. Location analysis indicated a sustainability trade-off between France, USA, Poland, and China, with the written order of declining MSP and increasing GWP. Continuous processing promised reducing the MSP by 18-27 %, and the GWP by 17-31 %. In-situ product extraction during fermentation was estimated to lower the MSP by 41-61 %, and the GWP by 30-75 %. In addition to showcasing a combined TEA-LCA on biopharmaceuticals, the early-stage assessment approach guides bioprocess optimization.
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Affiliation(s)
- Deniz Etit
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Ólafur Ögmundarson
- Faculty of Food Science and Nutrition, University of Iceland, Aragata 14, 102 Reykjavík, Iceland
| | - Jie Zhang
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Michael Krogh Jensen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Sumesh Sukumara
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark.
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Lee GH, Kim DW, Jin YH, Kim SM, Lim ES, Cha MJ, Ko JK, Gong G, Lee SM, Um Y, Han SO, Ahn JH. Biotechnological Plastic Degradation and Valorization Using Systems Metabolic Engineering. Int J Mol Sci 2023; 24:15181. [PMID: 37894861 PMCID: PMC10607142 DOI: 10.3390/ijms242015181] [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: 09/22/2023] [Revised: 10/10/2023] [Accepted: 10/13/2023] [Indexed: 10/29/2023] Open
Abstract
Various kinds of plastics have been developed over the past century, vastly improving the quality of life. However, the indiscriminate production and irresponsible management of plastics have led to the accumulation of plastic waste, emerging as a pressing environmental concern. To establish a clean and sustainable plastic economy, plastic recycling becomes imperative to mitigate resource depletion and replace non-eco-friendly processes, such as incineration. Although chemical and mechanical recycling technologies exist, the prevalence of composite plastics in product manufacturing complicates recycling efforts. In recent years, the biodegradation of plastics using enzymes and microorganisms has been reported, opening a new possibility for biotechnological plastic degradation and bio-upcycling. This review provides an overview of microbial strains capable of degrading various plastics, highlighting key enzymes and their role. In addition, recent advances in plastic waste valorization technology based on systems metabolic engineering are explored in detail. Finally, future perspectives on systems metabolic engineering strategies to develop a circular plastic bioeconomy are discussed.
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Affiliation(s)
- Ga Hyun Lee
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Do-Wook Kim
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Yun Hui Jin
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Sang Min Kim
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Eui Seok Lim
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Min Ji Cha
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Ja Kyong Ko
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Division of Energy and Environment Technology, KIST School, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - Gyeongtaek Gong
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Division of Energy and Environment Technology, KIST School, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - Sun-Mi Lee
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Division of Energy and Environment Technology, KIST School, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - Youngsoon Um
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Division of Energy and Environment Technology, KIST School, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - Sung Ok Han
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Jung Ho Ahn
- Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Division of Energy and Environment Technology, KIST School, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
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Pasotti L, De Marchi D, Casanova M, Frusteri Chiacchiera A, Cusella De Angelis MG, Calvio C, Magni P. Design of a stable ethanologenic bacterial strain without heterologous plasmids and antibiotic resistance genes for efficient ethanol production from concentrated dairy waste. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:57. [PMID: 37005680 PMCID: PMC10067303 DOI: 10.1186/s13068-023-02298-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 03/03/2023] [Indexed: 04/04/2023]
Abstract
Engineering sustainable bioprocesses that convert abundant waste into fuels is pivotal for efficient production of renewable energy. We previously engineered an Escherichia coli strain for optimized bioethanol production from lactose-rich wastewater like concentrated whey permeate (CWP), a dairy effluent obtained from whey valorization processes. Although attractive fermentation performances were reached, significant improvements are required to eliminate recombinant plasmids, antibiotic resistances and inducible promoters, and increase ethanol tolerance. Here, we report a new strain with chromosomally integrated ethanologenic pathway under the control of a constitutive promoter, without recombinant plasmids and resistance genes. The strain showed extreme stability in 1-month subculturing, with CWP fermentation performances similar to the ethanologenic plasmid-bearing strain. We then investigated conditions enabling efficient ethanol production and sugar consumption by changing inoculum size and CWP concentration, revealing toxicity- and nutritional-related bottlenecks. The joint increase of ethanol tolerance, via adaptive evolution, and supplementation of small ammonium sulphate amounts (0.05% w/v) enabled a fermentation boost with 6.6% v/v ethanol titer, 1.2 g/L/h rate, 82.5% yield, and cell viability increased by three orders of magnitude. Our strain has attractive features for industrial settings and represents a relevant improvement in the existing ethanol production biotechnologies.
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Affiliation(s)
- Lorenzo Pasotti
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy.
- Centre for Health Technologies, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy.
| | - Davide De Marchi
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
- Centre for Health Technologies, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
| | - Michela Casanova
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
- Centre for Health Technologies, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
| | - Angelica Frusteri Chiacchiera
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
- Centre for Health Technologies, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
| | - Maria Gabriella Cusella De Angelis
- Centre for Health Technologies, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Via Forlanini 8, 27100, Pavia, Italy
| | - Cinzia Calvio
- Centre for Health Technologies, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, 27100, Pavia, Italy
| | - Paolo Magni
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
- Centre for Health Technologies, University of Pavia, Via Ferrata 5, 27100, Pavia, Italy
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Huang T, Ma Y. Advances in biosynthesis of higher alcohols in Escherichia coli. World J Microbiol Biotechnol 2023; 39:125. [PMID: 36941474 DOI: 10.1007/s11274-023-03580-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/13/2023] [Indexed: 03/23/2023]
Abstract
In recent years, the development of green energy to replace fossil fuels has been the focus of research. Higher alcohols are important biofuels and chemicals. The production of higher alcohols in microbes has gained attention due to its environmentally friendly character. Higher alcohols have been synthesized in model microorganism Escherichia coli, and the production has reached the gram level through enhancement of metabolic flow, the balance of reducing power and the optimization of fermentation processes. Sustainable bio-higher alcohols production is expected to replace fossil fuels as a green and renewable energy source. Therefore, this review summarizes the latest developments in producing higher alcohols (C3-C6) by E. coli, elucidate the main bottlenecks limiting the biosynthesis of higher alcohols, and proposes potential engineering strategies of improving the production of biological higher alcohols. This review would provide a theoretical basis for further research on higher alcohols production by E. coli.
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Affiliation(s)
- Tong Huang
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Yuanyuan Ma
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China.
- School of Marin Science and Technology, Tianjin University, Tianjin, 300072, China.
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin, 300072, China.
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12
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Schultes FPJ, Haarmann M, Tischler D, Mügge C. Primary alcohols as substrates or products in whole-cell biocatalysis: Toxicity for Escherichia coli expression strains. MOLECULAR CATALYSIS 2023. [DOI: 10.1016/j.mcat.2023.112979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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13
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Härrer D, Elreedy A, Ali R, Hille-Reichel A, Gescher J. Probing the robustness of Geobacter sulfurreducens against fermentation hydrolysate for uses in bioelectrochemical systems. BIORESOURCE TECHNOLOGY 2023; 369:128363. [PMID: 36423764 DOI: 10.1016/j.biortech.2022.128363] [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: 09/29/2022] [Revised: 11/14/2022] [Accepted: 11/16/2022] [Indexed: 06/16/2023]
Abstract
In this study, impacts of toxic ions/acids found in real fermentation-hydrolysate on the model exoelectrogenic G. sulfurreducens were investigated. Initially, different concentrations of acetate, butyrate, propionate, Na+, and K+ were tested, individually and in combination, for effects on the planktonic growth, followed by validation with diluted-hydrolysate. Meanwhile, it could be shown that (1) excess Na+ (≥100 mM) causes inhibition that can be reduced by K+ replacement, (2) butyrate (≥10 mM) induces higher toxicity than propionate, and (3) hydrolysate induces synergistic inhibition to G. sulfurreducens where organic constituents contributed more than Na+. Afterwards, compared with impacts on planktonic cells, the pre-enriched anodic biofilm of G. sulfurreducens in BESs showed higher robustness against diluted-hydrolysate, achieving current densities of 1.4-1.7 A/m2 (at up to ∼30 mM butyrate and propionate as well as ∼240 mM Na+). As a conclusion, using G. sulfurreducens in BESs dealing with fermentation-hydrolysate can be regulated for efficacious energy recovery.
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Affiliation(s)
- Daniel Härrer
- Institute for Applied Biosciences - Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Ahmed Elreedy
- Institute of Technical Microbiology, Hamburg University of Technology, Hamburg 21073, Germany
| | - Rowayda Ali
- Engler-Bunte-Institut, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Andrea Hille-Reichel
- Engler-Bunte-Institut, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Johannes Gescher
- Institute for Applied Biosciences - Department of Applied Biology, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany; Institute of Technical Microbiology, Hamburg University of Technology, Hamburg 21073, Germany.
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14
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Straathof AJ. Modelling of end-product inhibition in fermentation. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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15
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Thorough Investigation of the Effects of Cultivation Factors on Polyhydroalkanoates (PHAs) Production by Cupriavidus necator from Food Waste-Derived Volatile Fatty Acids. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8110605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Volatile fatty acids (VFAs) have become promising candidates for replacing the conventional expensive carbon sources used to produce polyhydroxyalkanoates (PHAs). Considering the inhibitory effect of VFAs at high concentrations and the influence of VFA mixture composition on bacterial growth and PHA production, a thorough investigation of different cultivation parameters such as VFA concentrations and composition (synthetic and waste-derived VFAs) media, pH, aeration, C/N ratio, and type of nitrogen sources was conducted. Besides common VFAs of acetic, butyric and propionic acids, Cupriavidus necator showed good capability for assimilating longer-chained carboxylate compounds of valeric, isovaleric, isobutyric and caproic acids in feasible concentrations of 2.5–5 g/L. A combination of pH control at 7.0, C/N of 6, and aeration of 1 vvm was found to be the optimal condition for the bacterial growth, yielding a maximum PHA accumulation and PHA yield on biomass of 1.5 g/L and 56%, respectively, regardless of the nitrogen sources. The accumulated PHA was found to be poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with the percentage of hydroxybutyrate in the range 91–96%. Any limitation in the cultivation factors was found to enhance the PHA yield, the promotion of which was a consequence of the reduction in biomass production.
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16
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Liu C, Cui X, Chen W, Ma X, Prather KJ, Zhou K, Wu J. Synthesis of Oxygenated Sesquiterpenoids Enabled by Combining Metabolic Engineering and Visible‐Light Photocatalysis. Chemistry 2022; 28:e202201230. [DOI: 10.1002/chem.202201230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Chenguang Liu
- Department of Chemistry National University of Singapore Singapore 117543 Singapore
| | - Xiaoyi Cui
- Department of Chemical and Biomolecular Engineering National University of Singapore Singapore 119077 Singapore
- Disruptive & Sustainable Technologies for Agricultural Precision Singapore-MIT Alliance for Research and Technology Singapore
| | - Wei Chen
- Department of Chemistry National University of Singapore Singapore 117543 Singapore
| | - Xiaoqiang Ma
- Department of Chemical and Biomolecular Engineering National University of Singapore Singapore 119077 Singapore
| | - Kristala J. Prather
- Disruptive & Sustainable Technologies for Agricultural Precision Singapore-MIT Alliance for Research and Technology Singapore
- Department of Chemical Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA
| | - Kang Zhou
- Department of Chemical and Biomolecular Engineering National University of Singapore Singapore 119077 Singapore
- Disruptive & Sustainable Technologies for Agricultural Precision Singapore-MIT Alliance for Research and Technology Singapore
| | - Jie Wu
- Department of Chemistry National University of Singapore Singapore 117543 Singapore
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17
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Escherichia coli minicells with targeted enzymes as bioreactors for producing toxic compounds. Metab Eng 2022; 73:214-224. [PMID: 35970507 DOI: 10.1016/j.ymben.2022.08.006] [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: 04/27/2022] [Revised: 07/05/2022] [Accepted: 08/06/2022] [Indexed: 11/20/2022]
Abstract
Formed by aberrant cell division, minicells possess functional metabolism despite their inability to grow and divide. Minicells exhibit not only superior stability when compared with bacterial cells but also exceptional tolerance-characteristics that are essential for a de novo bioreactor platform. Accordingly, we engineered minicells to accumulate protein, ensuring sufficient production capability. When tested with chemicals regarded as toxic against cells, the engineered minicells produced titers of C6-C10 alcohols and esters, far surpassing the corresponding production from bacterial cells. Additionally, microbial autoinducer production that is limited in expanding bacterial population was conducted in the minicells. Because bacterial population growth was nonexistent, the minicells produced autoinducers in constant amounts, which allowed precise control of the bacterial population having autoinducer-responsive gene circuits. When bacterial population growth was nonexistent, the minicells produced autoinducers in constant amounts, which allowed precise control of the bacterial population having autoinducer-based gene circuits with the minicells. This study demonstrates the potential of minicells as bioreactors suitable for products with known limitations in microbial production, thus providing new possibilities for bioreactor engineering.
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18
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Impact of brewery wastewater inhibitors in pure and mixed cultures of the yeast Rhodosporidium toruloides NCYC 921 and the microalga Tetradesmus obliquus ACOI 204/07. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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19
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Stark C, Münßinger S, Rosenau F, Eikmanns BJ, Schwentner A. The Potential of Sequential Fermentations in Converting C1 Substrates to Higher-Value Products. Front Microbiol 2022; 13:907577. [PMID: 35722332 PMCID: PMC9204031 DOI: 10.3389/fmicb.2022.907577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Today production of (bulk) chemicals and fuels almost exclusively relies on petroleum-based sources, which are connected to greenhouse gas release, fueling climate change. This increases the urgence to develop alternative bio-based technologies and processes. Gaseous and liquid C1 compounds are available at low cost and often occur as waste streams. Acetogenic bacteria can directly use C1 compounds like CO, CO2, formate or methanol anaerobically, converting them into acetate and ethanol for higher-value biotechnological products. However, these microorganisms possess strict energetic limitations, which in turn pose limitations to their potential for biotechnological applications. Moreover, efficient genetic tools for strain improvement are often missing. However, focusing on the metabolic abilities acetogens provide, they can prodigiously ease these technological disadvantages. Producing acetate and ethanol from C1 compounds can fuel via bio-based intermediates conversion into more energy-demanding, higher-value products, by deploying aerobic organisms that are able to grow with acetate/ethanol as carbon and energy source. Promising new approaches have become available combining these two fermentation steps in sequential approaches, either as separate fermentations or as integrated two-stage fermentation processes. This review aims at introducing, comparing, and evaluating the published approaches of sequential C1 fermentations, delivering a list of promising organisms for the individual fermentation steps and giving an overview of the existing broad spectrum of products based on acetate and ethanol. Understanding of these pioneering approaches allows collecting ideas for new products and may open avenues toward making full use of the technological potential of these concepts for establishment of a sustainable biotechnology.
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Affiliation(s)
- Christina Stark
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Sini Münßinger
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Frank Rosenau
- Institute of Pharmaceutical Biotechnology, University of Ulm, Ulm, Germany
| | - Bernhard J. Eikmanns
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
- *Correspondence: Bernhard J. Eikmanns,
| | - Andreas Schwentner
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
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20
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Cell-free prototyping enables implementation of optimized reverse β-oxidation pathways in heterotrophic and autotrophic bacteria. Nat Commun 2022; 13:3058. [PMID: 35650184 PMCID: PMC9160091 DOI: 10.1038/s41467-022-30571-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 05/09/2022] [Indexed: 11/12/2022] Open
Abstract
Carbon-negative synthesis of biochemical products has the potential to mitigate global CO2 emissions. An attractive route to do this is the reverse β-oxidation (r-BOX) pathway coupled to the Wood-Ljungdahl pathway. Here, we optimize and implement r-BOX for the synthesis of C4-C6 acids and alcohols. With a high-throughput in vitro prototyping workflow, we screen 762 unique pathway combinations using cell-free extracts tailored for r-BOX to identify enzyme sets for enhanced product selectivity. Implementation of these pathways into Escherichia coli generates designer strains for the selective production of butanoic acid (4.9 ± 0.1 gL−1), as well as hexanoic acid (3.06 ± 0.03 gL−1) and 1-hexanol (1.0 ± 0.1 gL−1) at the best performance reported to date in this bacterium. We also generate Clostridium autoethanogenum strains able to produce 1-hexanol from syngas, achieving a titer of 0.26 gL−1 in a 1.5 L continuous fermentation. Our strategy enables optimization of r-BOX derived products for biomanufacturing and industrial biotechnology. An attractive route for carbon-negative synthesis of biochemical products is the reverse β-oxidation pathway coupled to the Wood-Ljungdahl pathway. Here the authors use a high-throughput in vitro prototyping workflow to screen 762 unique pathway combinations using cell-free extracts tailored for r-BOX to identify enzyme sets for enhanced product selectivity.
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21
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Seo H, Giannone RJ, Yang YH, Trinh CT. Proteome reallocation enables the selective de novo biosynthesis of non-linear, branched-chain acetate esters. Metab Eng 2022; 73:38-49. [PMID: 35561848 DOI: 10.1016/j.ymben.2022.05.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/21/2022] [Accepted: 05/06/2022] [Indexed: 10/25/2022]
Abstract
The one-carbon recursive ketoacid elongation pathway is responsible for making various branched-chain amino acids, aldehydes, alcohols, and acetate esters in living cells. Controlling selective microbial biosynthesis of these target molecules at high efficiency is challenging due to enzyme promiscuity, regulation, and metabolic burden. In this study, we present a systematic modular design approach to control proteome reallocation for selective microbial biosynthesis of branched-chain acetate esters. Through pathway modularization, we partitioned the branched-chain ester pathways into four submodules including keto-isovalerate submodule for converting pyruvate to keto-isovalerate, ketoacid elongation submodule for producing longer carbon-chain keto-acids, ketoacid decarboxylase submodule for converting ketoacids to alcohols, and alcohol acyltransferase submodule for producing branched-chain acetate esters by condensing alcohols and acetyl-CoA. By systematic manipulation of pathway gene replication and transcription, enzyme specificity of the first committed steps of these submodules, and downstream competing pathways, we demonstrated selective microbial production of isoamyl acetate over isobutyl acetate. We found that the optimized isoamyl acetate pathway globally redistributed the amino acid fractions in the proteomes and required up to 23-31% proteome reallocation at the expense of other cellular resources, such as those required to generate precursor metabolites and energy for growth and amino acid biosynthesis. From glucose fed-batch fermentation, the engineered strains produced isoamyl acetate up to a titer of 8.8 g/L (>0.25 g/L toxicity limit), a yield of 0.22 g/g (61% of maximal theoretical value), and 86% selectivity, achieving the highest titers, yields and selectivity of isoamyl acetate reported to date.
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Affiliation(s)
- Hyeongmin Seo
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Richard J Giannone
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Yung-Hun Yang
- Department of Biological Engineering, Konkuk University, Seoul, South Korea
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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22
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Dominic D, Baidurah S. Recent Developments in Biological Processing Technology for Palm Oil Mill Effluent Treatment-A Review. BIOLOGY 2022; 11:525. [PMID: 35453724 PMCID: PMC9031994 DOI: 10.3390/biology11040525] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/22/2022] [Accepted: 02/25/2022] [Indexed: 11/16/2022]
Abstract
POME is the most voluminous waste generated from palm oil milling activities. The discharge of POME into the environment without any treatment processing could inflict an undesirable hazard to humans and the environment due to its high amount of toxins, organic, and inorganic materials. The treatment of POME prior to discharge into the environment is utmost required to protect the liability for human health and the environment. Biological treatments are preferable due to eco-friendly attributes that are technically and economically feasible. The goal of this review article is to highlight the current state of development in the biological processing technologies for POME treatment. These biological processing technologies are conducted in the presence of fungi, bacteria, microalgae, and a consortium of microorganisms. Numerous microbes are listed to identify the most efficient strain by monitoring the BOD, COD, working volume of the reactor, and treatment time. The most effective processing technology for POME treatment uses an upflow anaerobic sludge blanket reactor with the COD value of 99%, hydraulic retention time of 7.2 days, and a working volume of 4.7 litres. Biological processing technologies are mooted as an efficient and sustainable management practice of POME waste.
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Affiliation(s)
| | - Siti Baidurah
- School of Industrial Technology, Universiti Sains Malaysia, Minden, Penang 11800, Malaysia;
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23
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Abstract
The facultative chemolithoautotroph Cupriavidus necator H16 is able to grow aerobically either with organic substrates or H2 and CO2 s and it can accumulate large amounts of (up to 90%) poly (3-hydroxybutyrate), a polyhydroxyalkanoate (PHA) biopolymer. The ability of this organism to co-utilize volatile fatty acids (VFAs) and CO2 as sources of carbon under mixotrophic growth conditions was investigated and PHA production was monitored. PHA accumulation was assessed under aerobic conditions, with either individual VFAs or in mixtures, under three different conditions—with CO2 as additional carbon source, without CO2 and with CO2 and H2 as additional sources of carbon and energy. VFAs utilisation rates were slower in the presence of CO2. PHA production was significantly higher when cultures were grown mixotrophically and with H2 as an additional energy source compared to heterotrophic or mixotrophic growth conditions, without H2. Furthermore, a two-step VFA feeding regime was found to be the most effective method for PHA accumulation. It was used for PHA production mixotrophically using CO2, H2 and VFA mixture derived from an anaerobic digestor (AD). The data obtained demonstrated that process parameters need to be carefully monitored to avoid VFA toxicity and low product accumulation.
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24
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Kang D, Liu W, Kakahi FB, Delvigne F. Combined utilization of metabolic inhibitors to prevent synergistic multi-species biofilm formation. AMB Express 2022; 12:32. [PMID: 35244796 PMCID: PMC8897544 DOI: 10.1186/s13568-022-01363-4] [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: 12/02/2021] [Accepted: 02/12/2022] [Indexed: 12/04/2022] Open
Abstract
Biofilm is ubiquitous in industrial water systems, causing biofouling and leading to heat transfer efficiency decreases. In particular, multi-species living in biofilms could boost biomass production and enhance treatment resistance. In this study, a total of 37 bacterial strains were isolated from a cooling tower biofilm where acetic acid and propionic acid were detected as the main carbon sources. These isolates mainly belonged to Proteobacteria and Firmicutes, which occupied more than 80% of the total strains according to the 16S rRNA gene amplicon sequencing. Four species (Acinetobacter sp. CTS3, Corynebacterium sp. CTS5, Providencia sp. CTS12, and Pseudomonas sp. CTS17) were observed co-existing in the synthetic medium. Quantitative comparison of biofilm biomass from mono- and multi-species showed a synergistic effect towards biofilm formation among these four species. Three metabolic inhibitors (sulfathiazole, 3-bromopyruvic acid, and 3-nitropropionic acid) were employed to prevent biofilm formation based on their inhibitory effect on corresponding metabolic pathways. All of them displayed evident inhibition profiles to biofilm formation. Notably, combining these three inhibitors possessed a remarkable ability to block the multi-species biofilm development with lower concentrations, suggesting an enhanced effect appeared in simultaneous use. This study demonstrates that combined utilization of metabolic inhibitors is an alternative strategy to prevent multi-species biofilm formation. 37 bacterial strains were isolated and identified from a cooling tower biofilm. Synergistic effect of biofilm formation was observed among four species. Three metabolic inhibitors showed effective inhibition against biofilm formation. Targeting cellular metabolism is an effective way to inhibit biofilm formation.
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25
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Tarasava K, Lee SH, Chen J, Köpke M, Jewett MC, Gonzalez R. Reverse β-oxidation pathways for efficient chemical production. J Ind Microbiol Biotechnol 2022; 49:6537408. [PMID: 35218187 PMCID: PMC9118988 DOI: 10.1093/jimb/kuac003] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 01/25/2022] [Indexed: 12/04/2022]
Abstract
Microbial production of fuels, chemicals, and materials has the potential to reduce greenhouse gas emissions and contribute to a sustainable bioeconomy. While synthetic biology allows readjusting of native metabolic pathways for the synthesis of desired products, often these native pathways do not support maximum efficiency and are affected by complex regulatory mechanisms. A synthetic or engineered pathway that allows modular synthesis of versatile bioproducts with minimal enzyme requirement and regulation while achieving high carbon and energy efficiency could be an alternative solution to address these issues. The reverse β-oxidation (rBOX) pathways enable iterative non-decarboxylative elongation of carbon molecules of varying chain lengths and functional groups with only four core enzymes and no ATP requirement. Here, we describe recent developments in rBOX pathway engineering to produce alcohols and carboxylic acids with diverse functional groups, along with other commercially important molecules such as polyketides. We discuss the application of rBOX beyond the pathway itself by its interfacing with various carbon-utilization pathways and deployment in different organisms, which allows feedstock diversification from sugars to glycerol, carbon dioxide, methane, and other substrates.
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Affiliation(s)
- Katia Tarasava
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, FL, USA
| | - Seung Hwan Lee
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, FL, USA
| | - Jing Chen
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, FL, USA
| | | | - Michael C Jewett
- Department of Chemical and Biological Engineering and Center for Synthetic Biology, Northwestern University, Evanston, IL, USA
| | - Ramon Gonzalez
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, FL, USA
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26
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Salinas-Almaguer S, Mell M, Almendro-Vedia VG, Calero M, Robledo-Sánchez KCM, Ruiz-Suarez C, Alarcón T, Barrio RA, Hernández-Machado A, Monroy F. Membrane rigidity regulates E. coli proliferation rates. Sci Rep 2022; 12:933. [PMID: 35042922 PMCID: PMC8766614 DOI: 10.1038/s41598-022-04970-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 01/04/2022] [Indexed: 12/23/2022] Open
Abstract
Combining single cell experiments, population dynamics and theoretical methods of membrane mechanics, we put forward that the rate of cell proliferation in E. coli colonies can be regulated by modifiers of the mechanical properties of the bacterial membrane. Bacterial proliferation was modelled as mediated by cell division through a membrane constriction divisome based on FtsZ, a mechanically competent protein at elastic interaction against membrane rigidity. Using membrane fluctuation spectroscopy in the single cells, we revealed either membrane stiffening when considering hydrophobic long chain fatty substances, or membrane softening if short-chained hydrophilic molecules are used. Membrane stiffeners caused hindered growth under normal division in the microbial cultures, as expected for membrane rigidification. Membrane softeners, however, altered regular cell division causing persistent microbes that abnormally grow as long filamentous cells proliferating apparently faster. We invoke the concept of effective growth rate under the assumption of a heterogeneous population structure composed by distinguishable individuals with different FtsZ-content leading the possible forms of cell proliferation, from regular division in two normal daughters to continuous growing filamentation and budding. The results settle altogether into a master plot that captures a universal scaling between membrane rigidity and the divisional instability mediated by FtsZ at the onset of membrane constriction.
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Affiliation(s)
- Samuel Salinas-Almaguer
- Centro de Investigación y de Estudios Avanzados, Unidad Monterrey, Vía del Conocimiento 201, PIIT, 66600, Apodaca, NL, Mexico
- Departamento de Química Física, Universidad Complutense de Madrid, Av. Complutense S/N, 28040, Madrid, Spain
| | - Michael Mell
- Departamento de Química Física, Universidad Complutense de Madrid, Av. Complutense S/N, 28040, Madrid, Spain
| | - Victor G Almendro-Vedia
- Departamento de Química Física, Universidad Complutense de Madrid, Av. Complutense S/N, 28040, Madrid, Spain
| | - Macarena Calero
- Departamento de Química Física, Universidad Complutense de Madrid, Av. Complutense S/N, 28040, Madrid, Spain
- Translational Biophysics, Instituto de Investigación Sanitaria Hospital Doce de Octubre (IMAS12), Av. Andalucía S/N, 28041, Madrid, Spain
| | | | - Carlos Ruiz-Suarez
- Centro de Investigación y de Estudios Avanzados, Unidad Monterrey, Vía del Conocimiento 201, PIIT, 66600, Apodaca, NL, Mexico
| | - Tomás Alarcón
- ICREA, Pg. Lluís Companys 23, 08010, Barcelona, Spain
- Centre de Recerca Matemàtica, Edifici C, Campus de Bellaterra, 08193, Bellaterra, Barcelona, Spain
- Departament de Matemàtiques, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
- Barcelona Graduate School of Mathematics (BGSMath), Barcelona, Spain
| | - Rafael A Barrio
- Instituto de Fisica, U.N.A.M., Apartado Postal 20-364, 01000, Mexico, D.F., Mexico
| | - Aurora Hernández-Machado
- Centre de Recerca Matemàtica, Edifici C, Campus de Bellaterra, 08193, Bellaterra, Barcelona, Spain.
- Departament Fisica de la Materia Condensada, Facultat de Fisica, Universitat de Barcelona, Diagonal 645, 08028, Barcelona, Spain.
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, Spain.
| | - Francisco Monroy
- Departamento de Química Física, Universidad Complutense de Madrid, Av. Complutense S/N, 28040, Madrid, Spain.
- Translational Biophysics, Instituto de Investigación Sanitaria Hospital Doce de Octubre (IMAS12), Av. Andalucía S/N, 28041, Madrid, Spain.
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27
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Controlling selectivity of modular microbial biosynthesis of butyryl-CoA-derived designer esters. Metab Eng 2021; 69:262-274. [PMID: 34883244 DOI: 10.1016/j.ymben.2021.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/21/2021] [Accepted: 12/01/2021] [Indexed: 02/02/2023]
Abstract
Short-chain esters have broad utility as flavors, fragrances, solvents, and biofuels. Controlling selectivity of ester microbial biosynthesis has been an outstanding metabolic engineering problem. In this study, we enabled the de novo fermentative microbial biosynthesis of butyryl-CoA-derived designer esters (e.g., butyl acetate, ethyl butyrate, butyl butyrate) in Escherichia coli with controllable selectivity. Using the modular design principles, we generated the butyryl-CoA-derived ester pathways as exchangeable production modules compatible with an engineered chassis cell for anaerobic production of designer esters. We designed these modules derived from an acyl-CoA submodule (e.g., acetyl-CoA, butyryl-CoA), an alcohol submodule (e.g., ethanol, butanol), a cofactor regeneration submodule (e.g., NADH), and an alcohol acetyltransferase (AAT) submodule (e.g., ATF1, SAAT) for rapid module construction and optimization by manipulating replication (e.g., plasmid copy number), transcription (e.g., promoters), translation (e.g., codon optimization), pathway enzymes, and pathway induction conditions. To further enhance production of designer esters with high selectivity, we systematically screened various strategies of protein solubilization using protein fusion tags and chaperones to improve the soluble expression of multiple pathway enzymes. Finally, our engineered ester-producing strains could achieve 19-fold increase in butyl acetate production (0.64 g/L, 96% selectivity), 6-fold increase in ethyl butyrate production (0.41 g/L, 86% selectivity), and 13-fold increase in butyl butyrate production (0.45 g/L, 54% selectivity) as compared to the initial strains. Overall, this study presented a generalizable framework to engineer modular microbial platforms for anaerobic production of butyryl-CoA-derived designer esters from renewable feedstocks.
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Osborne MG, Geiger CJ, Corzett CH, Kram KE, Finkel SE. Removal of Toxic Volatile Compounds in Batch Culture Prolongs Stationary Phase and Delays Death of Escherichia coli. Appl Environ Microbiol 2021; 87:e0186021. [PMID: 34613759 PMCID: PMC8612265 DOI: 10.1128/aem.01860-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 09/26/2021] [Indexed: 12/28/2022] Open
Abstract
The mechanisms controlling entry into and exit from the death phase in the bacterial life cycle remain unclear. Although bacterial growth studies in batch cultures traditionally focus on the first three phases during incubation, two additional phases, the death phase and the long-term stationary phase, are less understood. Although there are a number of stressors that arise during long-term batch culture, including nutrient depletion and the accumulation of metabolic toxins such as reactive oxidative species, their roles in cell death are not well-defined. By manipulating the environmental conditions of Escherichia coli incubated in long-term batch culture through chemical and mechanical means, we investigated the role of volatile metabolic toxins in modulating the onset of the death phase. Here, we demonstrate that with the introduction of substrates with high binding affinities for volatile compounds, toxic by-products of normal cell metabolism, into the headspace of batch cultures, cells display a prolonged stationary phase and delayed entry into the death phase. The addition of these substrates allows cultures to maintain a high cell density for hours to days longer than cultures incubated under standard growth conditions. A similar effect is observed when the gaseous headspace in culture flasks is continuously replaced with sterile air, mechanically preventing the accumulation of metabolic by-products in batch cultures. We establish that toxic compound(s) are produced during the exponential phase, demonstrate that buildup of toxic by-products influence entry into the death phase, and present a novel tool for improving high-density growth in batch culture that may be used in future research or industrial or biotechnology applications. IMPORTANCE Bacteria, such as Escherichia coli, are routinely used in the production of biomaterials because of their efficient and sustainable capacity for synthesis of bioproducts. Industrial applications of microbial synthesis typically utilize cells in the stationary phase, when cultures have the greatest density of viable cells. By manipulating culture conditions to delay the transition from the stationary phase to the death phase, we can prolong the stationary phase on a scale of hours to days, thereby maintaining the maximum density of cells that would otherwise quickly decline. Characterization of the mechanisms that control entry into the death phase for the model organism E. coli not only deepens our understanding of the bacterial life cycle but also presents an opportunity to enhance current protocols for batch culture growth and explore similar effects in a variety of widely used bacterial strains.
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Affiliation(s)
- Melisa G. Osborne
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Christopher J. Geiger
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Christopher H. Corzett
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Karin E. Kram
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Steven E. Finkel
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
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Sawant N, Singh H, Appukuttan D. Overview of the Cellular Stress Responses Involved in Fatty Acid Overproduction in E. coli. Mol Biotechnol 2021; 64:373-387. [PMID: 34796451 DOI: 10.1007/s12033-021-00426-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 11/10/2021] [Indexed: 12/29/2022]
Abstract
Research on microbial fatty acid metabolism started in the late 1960s, and till date, various developments have aided in elucidating the fatty acid metabolism in great depth. Over the years, synthesis of microbial fatty acid has drawn industrial attention due to its diverse applications. However, fatty acid overproduction imparts various stresses on its metabolic pathways causing a bottleneck to further increase the fatty acid yields. Numerous strategies to increase fatty acid titres in Escherichia coli by pathway modulation have already been published, but the stress generated during fatty acid overproduction is relatively less studied. Stresses like pH, osmolarity and oxidative stress, not only lower fatty acid titres, but also alter the cell membrane composition, protein expression and membrane fluidity. This review discusses an overview of fatty acid synthesis pathway and presents a panoramic view of various stresses caused due to fatty acid overproduction in E. coli. It also addresses how certain stresses like high temperature and nitrogen limitation can boost fatty acid production. This review paper also highlights the interconnections that exist between these stresses.
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Affiliation(s)
- Neha Sawant
- Department of Biological Sciences, Sunandan Divatia School of Science, NMIMS Deemed to be University, Vile Parle (West), Mumbai, 400056, India
| | - Harinder Singh
- Department of Biological Sciences, Sunandan Divatia School of Science, NMIMS Deemed to be University, Vile Parle (West), Mumbai, 400056, India.
| | - Deepti Appukuttan
- Biosystems Engineering Lab, Department of Chemical Engineering, IIT Bombay, Powai, Mumbai, 400076, India.
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Current Progress in Production of Building-Block Organic Acids by Consolidated Bioprocessing of Lignocellulose. FERMENTATION-BASEL 2021. [DOI: 10.3390/fermentation7040248] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Several organic acids have been indicated among the top value chemicals from biomass. Lignocellulose is among the most attractive feedstocks for biorefining processes owing to its high abundance and low cost. However, its highly complex nature and recalcitrance to biodegradation hinder development of cost-competitive fermentation processes. Here, current progress in development of single-pot fermentation (i.e., consolidated bioprocessing, CBP) of lignocellulosic biomass to high value organic acids will be examined, based on the potential of this approach to dramatically reduce process costs. Different strategies for CBP development will be considered such as: (i) design of microbial consortia consisting of (hemi)cellulolytic and valuable-compound producing strains; (ii) engineering of microorganisms that combine biomass-degrading and high-value compound-producing properties in a single strain. The present review will mainly focus on production of organic acids with application as building block chemicals (e.g., adipic, cis,cis-muconic, fumaric, itaconic, lactic, malic, and succinic acid) since polymer synthesis constitutes the largest sector in the chemical industry. Current research advances will be illustrated together with challenges and perspectives for future investigations. In addition, attention will be dedicated to development of acid tolerant microorganisms, an essential feature for improving titer and productivity of fermentative production of acids.
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Bohnenkamp AC, Wijffels RH, Kengen SWM, Weusthuis RA. Co-production of hydrogen and ethyl acetate in Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:192. [PMID: 34598726 PMCID: PMC8487115 DOI: 10.1186/s13068-021-02036-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/07/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Ethyl acetate (C4H8O2) and hydrogen (H2) are industrially relevant compounds that preferably are produced via sustainable, non-petrochemical production processes. Both compounds are volatile and can be produced by Escherichia coli before. However, relatively low yields for hydrogen are obtained and a mix of by-products renders the sole production of hydrogen by micro-organisms unfeasible. High yields for ethyl acetate have been achieved, but accumulation of formate remained an undesired but inevitable obstacle. Coupling ethyl acetate production to the conversion of formate into H2 may offer an interesting solution to both drawbacks. Ethyl acetate production requires equimolar amounts of ethanol and acetyl-CoA, which enables a redox neutral fermentation, without the need for production of by-products, other than hydrogen and CO2. RESULTS We engineered Escherichia coli towards improved conversion of formate into H2 and CO2 by inactivating the formate hydrogen lyase repressor (hycA), both uptake hydrogenases (hyaAB, hybBC) and/or overexpressing the hydrogen formate lyase activator (fhlA), in an acetate kinase (ackA) and lactate dehydrogenase (ldhA)-deficient background strain. Initially 10 strains, with increasing number of modifications were evaluated in anaerobic serum bottles with respect to growth. Four reference strains ΔldhAΔackA, ΔldhAΔackA p3-fhlA, ΔldhAΔackAΔhycAΔhyaABΔhybBC and ΔldhAΔackAΔhycAΔhyaABΔhybBC p3-fhlA were further equipped with a plasmid carrying the heterologous ethanol acyltransferase (Eat1) from Wickerhamomyces anomalus and analyzed with respect to their ethyl acetate and hydrogen co-production capacity. Anaerobic co-production of hydrogen and ethyl acetate via Eat1 was achieved in 1.5-L pH-controlled bioreactors. The cultivation was performed at 30 °C in modified M9 medium with glucose as the sole carbon source. Anaerobic conditions and gas stripping were established by supplying N2 gas. CONCLUSIONS We showed that the engineered strains co-produced ethyl acetate and hydrogen to yields exceeding 70% of the pathway maximum for ethyl acetate and hydrogen, and propose in situ product removal via gas stripping as efficient technique to isolate the products of interest.
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Affiliation(s)
- Anna C Bohnenkamp
- Bioprocess Engineering, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
| | - René H Wijffels
- Bioprocess Engineering, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
- Faculty of Biosciences and Aquaculture, Nord University, 8049, Bodø, Norway
| | - Servé W M Kengen
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Ruud A Weusthuis
- Bioprocess Engineering, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
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Lee JW, Seo H, Young C, Trinh CT. Probing specificities of alcohol acyltransferases for designer ester biosynthesis with a high-throughput microbial screening platform. Biotechnol Bioeng 2021; 118:4655-4667. [PMID: 34436763 DOI: 10.1002/bit.27926] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 08/13/2021] [Accepted: 08/22/2021] [Indexed: 11/07/2022]
Abstract
Alcohol acyltransferases (AATs) enables microbial biosynthesis of a large space of esters by condensing an alcohol and an acyl-CoA. However, substrate promiscuity of AATs prevents microbial biosynthesis of designer esters with high selectivity. Here, we developed a high-throughput microbial screening platform that facilitates rapid identification of AATs for designer ester biosynthesis. First, we established a microplate-based culturing technique with in situ fermentation and extraction of esters. We validated its capability in rapid profiling of the alcohol substrate specificity of 20 chloramphenicol acetyltransferase variants derived from Staphylococcus aureus (CATSa ) for microbial biosynthesis of acetate esters with various exogeneous alcohol supply. By coupling the microplate-based culturing technique with a previously established colorimetric assay, we developed a high-throughput microbial screening platform for AATs. We demonstrated that this platform could not only probe the alcohol substrate specificity of both native and engineered AATs but also identify the beneficial mutations in engineered AATs for enhanced ester synthesis. We anticipate the high-throughput microbial screening platform provides a useful tool to identify novel wildtype and engineered AATs that have important roles in nature and industrial biocatalysis for designer bioester production.
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Affiliation(s)
- Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Hyeongmin Seo
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, USA
| | - Caleb Young
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, USA
| | - Cong T Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, USA
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Hexanol biosynthesis from syngas by Clostridium carboxidivorans P7 - product toxicity, temperature dependence and in situ extraction. Heliyon 2021; 7:e07732. [PMID: 34409191 PMCID: PMC8361263 DOI: 10.1016/j.heliyon.2021.e07732] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 05/17/2021] [Accepted: 08/03/2021] [Indexed: 11/08/2022] Open
Abstract
Clostridium carboxidivorans converts syngas into industrial alcohols like hexanol, but titers may be limited by product toxicity. Investigation of IC50 at 30 °C (17.5 mM) and 37 °C (11.8 mM) revealed increased hexanol tolerance at lower temperatures. To avoid product toxicity, oleyl alcohol was added as an extraction solvent, increasing hexanol production nearly 2.5-fold to 23.9 mM (2.4 g/L) at 30 °C. This titer exceeds the concentration that is acutely toxic in the absence of a solvent, confirming the hypothesis that current hexanol production is limited by product toxicity. The solvent however had no positive effect at 37 °C. Furthermore, C. carboxidivorans cell membranes adapted to the higher temperature by incorporating more saturated fatty acids, but surprisingly not to hexanol. Corn oil and sunflower seed oil were tested as alternative, inexpensive extraction solvents. Hexanol titers were similar with all solvents, but oleyl alcohol achieved the highest extraction efficiency.
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Seo H, Lee JW, Giannone RJ, Dunlap NJ, Trinh CT. Engineering promiscuity of chloramphenicol acetyltransferase for microbial designer ester biosynthesis. Metab Eng 2021; 66:179-190. [PMID: 33872779 DOI: 10.1016/j.ymben.2021.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/06/2021] [Accepted: 04/11/2021] [Indexed: 02/07/2023]
Abstract
Robust and efficient enzymes are essential modules for metabolic engineering and synthetic biology strategies across biological systems to engineer whole-cell biocatalysts. By condensing an acyl-CoA and an alcohol, alcohol acyltransferases (AATs) can serve as interchangeable metabolic modules for microbial biosynthesis of a diverse class of ester molecules with broad applications as flavors, fragrances, solvents, and drop-in biofuels. However, the current lack of robust and efficient AATs significantly limits their compatibility with heterologous precursor pathways and microbial hosts. Through bioprospecting and rational protein engineering, we identified and engineered promiscuity of chloramphenicol acetyltransferases (CATs) from mesophilic prokaryotes to function as robust and efficient AATs compatible with at least 21 alcohol and 8 acyl-CoA substrates for microbial biosynthesis of linear, branched, saturated, unsaturated and/or aromatic esters. By plugging the best engineered CAT (CATec3 Y20F) into the gram-negative mesophilic bacterium Escherichia coli, we demonstrated that the recombinant strain could effectively convert various alcohols into desirable esters, for instance, achieving a titer of 13.9 g/L isoamyl acetate with 95% conversion by fed-batch fermentation. The recombinant E. coli was also capable of simulating the ester profile of roses with high conversion (>97%) and titer (>1 g/L) from fermentable sugars at 37 °C. Likewise, a recombinant gram-positive, cellulolytic, thermophilic bacterium Clostridium thermocellum harboring CATec3 Y20F could produce many of these esters from recalcitrant cellulosic biomass at elevated temperatures (>50 °C) due to the engineered enzyme's remarkable thermostability. Overall, the engineered CATs can serve as a robust and efficient platform for designer ester biosynthesis from renewable and sustainable feedstocks.
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Affiliation(s)
- Hyeongmin Seo
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Richard J Giannone
- Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Noah J Dunlap
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Center of Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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Santoscoy MC, Jarboe LR. A systematic framework for using membrane metrics for strain engineering. Metab Eng 2021; 66:98-113. [PMID: 33813035 DOI: 10.1016/j.ymben.2021.03.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 03/14/2021] [Accepted: 03/15/2021] [Indexed: 11/20/2022]
Abstract
The cell membrane plays a central role in the fitness and performance of microbial cell factories and therefore it is an attractive engineering target. The goal of this work is to develop a systematic framework for identifying membrane features for use as engineering targets. The metrics that describe the composition of the membrane can be visualized as "knobs" that modulate various "outcomes", such as physical properties of the membrane and metabolic activity in the form of growth and productivity, with these relationships varying depending on the condition. We generated a set of strains with altered membrane lipid composition via expression of des, fabA and fabB and performed a rigorous characterization of these knobs and outcomes across several individual inhibitory conditions. Here, the knobs are the relative abundance of unsaturated lipids and lipids containing cyclic rings; the average lipid length, and the ratio of linear and non-linear lipids (L/nL ratio). The outcomes are membrane permeability, hydrophobicity, fluidity, and specific growth rate. This characterization identified significant correlations between knobs and outcomes that were specific to individual inhibitors, but also were significant across all tested conditions. For example, across all conditions, the L/nL ratio is positively correlated with the cell surface hydrophobicity, and the average lipid length is positively correlated with specific growth rate. A subsequent analysis of the data with the individual inhibitors identified pairs of lipid metrics and membrane properties that were predicted to impact cell growth in seven modeled scenarios with two or more inhibitors. The L/nL ratio and the membrane hydrophobicity were predicted to impact cell growth with the highest frequency. We experimentally validated this prediction in the combined condition of 42 °C, 2.5 mM furfural and 2% v/v ethanol in minimal media. Membrane hydrophobicity was confirmed to be a significant predictor of ethanol production. This work demonstrates that membrane physical properties can be used to predict the performance of biocatalysts in single and multiple inhibitory conditions, and possibly as an engineering target. In this manner, membrane properties can possibly be used as screening or selection metrics for library- or evolution-based strain engineering.
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Affiliation(s)
- Miguel C Santoscoy
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA, 50011, USA
| | - Laura R Jarboe
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA, 50011, USA.
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Millard P, Enjalbert B, Uttenweiler-Joseph S, Portais JC, Létisse F. Control and regulation of acetate overflow in Escherichia coli. eLife 2021; 10:63661. [PMID: 33720011 PMCID: PMC8021400 DOI: 10.7554/elife.63661] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 03/12/2021] [Indexed: 12/21/2022] Open
Abstract
Overflow metabolism refers to the production of seemingly wasteful by-products by cells during growth on glucose even when oxygen is abundant. Two theories have been proposed to explain acetate overflow in Escherichia coli – global control of the central metabolism and local control of the acetate pathway – but neither accounts for all observations. Here, we develop a kinetic model of E. coli metabolism that quantitatively accounts for observed behaviours and successfully predicts the response of E. coli to new perturbations. We reconcile these theories and clarify the origin, control, and regulation of the acetate flux. We also find that, in turns, acetate regulates glucose metabolism by coordinating the expression of glycolytic and TCA genes. Acetate should not be considered a wasteful end-product since it is also a co-substrate and a global regulator of glucose metabolism in E. coli. This has broad implications for our understanding of overflow metabolism.
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Affiliation(s)
- Pierre Millard
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.,MetaToul-MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France
| | - Brice Enjalbert
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | | | - Jean-Charles Portais
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.,MetaToul-MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France.,RESTORE, Université de Toulouse, INSERM U1031, CNRS 5070, Université Toulouse III - Paul Sabatier, EFS, Toulouse, France
| | - Fabien Létisse
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.,Université Toulouse III - Paul Sabatier, Toulouse, France
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Abd El-Baky RM, Mandour SA, Ahmed EF, Hashem ZS, Sandle T, Mohamed DS. Virulence profiles of some Pseudomonas aeruginosa clinical isolates and their association with the suppression of Candida growth in polymicrobial infections. PLoS One 2020; 15:e0243418. [PMID: 33290412 PMCID: PMC7723275 DOI: 10.1371/journal.pone.0243418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 11/22/2020] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that can cause a variety of diseases especially in the hospital environment. However, this pathogen also exhibits antimicrobial activity against Gram-positive bacteria and fungi. This study aimed to characterize different virulence factors, secreted metabolites and to study their role in the suppression of Candida growth. Fifteen P. aeruginosa isolates were tested for their anticandidal activity against 3 different Candida spp. by the cross-streak method. The effect on hyphae production was tested microscopically using light and scanning electron microscopy (SEM). Polymerase chain reaction was used in the detection of some virulence genes. Lipopolysaccharide profile was performed using SDS-polyacrylamide gel stained with silver. Fatty acids were analyzed by GC-MS as methyl ester derivatives. It was found that 5 P. aeruginosa isolates inhibited all tested Candida spp. (50-100% inhibition), one isolate inhibited C. glabrata only and 3 isolates showed no activity against the tested Candida spp. The P. aeruginosa isolates inhibiting all Candida spp. were positive for all virulence genes. GC-Ms analysis revealed that isolates with high anticandidal activity showed spectra for several compounds, each known for their antifungal activity in comparison to those with low or no anticandidal activity. Hence, clinical isolates of P. aeruginosa showed Candida species-specific interactions by different means, giving rise to the importance of studying microbial interaction in polymicrobial infections and their contribution to causing disease.
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Affiliation(s)
- Rehab Mahmoud Abd El-Baky
- Department of Microbiology and Immunology, Faculty of Pharmacy, Minia University, Minia, Egypt
- Department of Microbiology and Immunology, Faculty of Pharmacy, Deraya University, Minia, Egypt
| | - Sahar A. Mandour
- Department of Microbiology and Immunology, Faculty of Pharmacy, Deraya University, Minia, Egypt
| | - Eman Farouk Ahmed
- Department of Microbiology and Immunology, Faculty of Pharmacy, Deraya University, Minia, Egypt
| | - Zeinab Shawky Hashem
- Department of Microbiology and Immunology, Faculty of Pharmacy, Minia University, Minia, Egypt
| | - Tim Sandle
- School of Health Sciences, Division of Pharmacy & Optometry, University of Manchester, Manchester, United Kingdom
| | - Doaa Safwat Mohamed
- Department of Microbiology and Immunology, Faculty of Pharmacy, Deraya University, Minia, Egypt
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Zhang Z, Taylor L, Shommu N, Ghosh S, Reimer R, Panaccione R, Kaur S, Hyun JE, Cai C, Deehan EC, Hotte N, Madsen KL, Raman M. A Diversified Dietary Pattern Is Associated With a Balanced Gut Microbial Composition of Faecalibacterium and Escherichia/Shigella in Patients With Crohn's Disease in Remission. J Crohns Colitis 2020; 14:1547-1557. [PMID: 32343765 DOI: 10.1093/ecco-jcc/jjaa084] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS Crohn's disease [CD] is associated with alterations in gut microbial composition and function. The present controlled-intervention study investigated the relationship between patterns of dietary intake and baseline gut microbiota in CD patients in remission and examined the effects of a dietary intervention in patients consuming a non-diversified diet [NDD]. METHODS Forty outpatients with quiescent CD were recruited in Calgary, Alberta, Canada. Based on 3-day food records, patients consuming a lower plant-based and higher red and processed meat-based diet were assigned to the NDD group [n = 15] and received a 12-week structured dietary intervention; all other patients were assigned to the diversified diet [DD] control group [n = 25] and received conventional management. Faecal microbiota composition, short chain fatty acids [SCFAs] and calprotectin were measured. RESULTS At baseline the NDD and DD groups had a different faecal microbial beta-diversity [p = 0.003, permutational multivariate analysis of variance]. The NDD group had lower Faecalibacterium and higher Escherichia/Shigella relative abundances compared to the DD group [3.3 ± 5.4% vs. 8.5 ± 10.6%; 6.9 ± 12.2% vs. 1.6 ± 4.4%; p ≤ 0.03, analysis of covariance]. These two genera showed a strong negative correlation [rs = -0.60, q = 0.0002]. Faecal butyrate showed a positive correlation with Faecalibacterium [rs = 0.52, q = 0.002], and an inhibitory relationship with Escherichia/Shigella abundance [four-parameter sigmoidal model, R = -0.83; rs = -0.44, q = 0.01], respectively. After the 12 weeks of dietary intervention, no difference in microbial beta-diversity between the two groups was observed [p = 0.43]. The NDD group demonstrated an increase in Faecalibacterium [p < 0.05, generalized estimated equation model], and resembled the DD group at the end of the intervention [p = 0.84, t-test with permutation]. We did not find an association of diet with faecal SCFAs or calprotectin. CONCLUSIONS Dietary patterns are associated with specific gut microbial compositions in CD patients in remission. A diet intervention in patients consuming a NDD modifies gut microbial composition to resemble that seen in patients consuming a DD. These results show that diet is important in shaping the microbial dysbiosis signature in CD towards a balanced community.
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Affiliation(s)
- Zhengxiao Zhang
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Lorian Taylor
- Department of Medicine, University of Calgary, Calgary, AB, Canada
| | - Nusrat Shommu
- Department of Medicine, University of Calgary, Calgary, AB, Canada
| | - Subrata Ghosh
- Institute of Translational Medicine, NIHR Biomedical Research Centre, University of Birmingham and Birmingham University Hospitals, Birmingham, UK
| | - Raylene Reimer
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | - Remo Panaccione
- Department of Medicine, University of Calgary, Calgary, AB, Canada
| | - Sandeep Kaur
- Department of Medicine, University of Calgary, Calgary, AB, Canada
| | - Jae Eun Hyun
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Chenxi Cai
- Program for Pregnancy and Postpartum Health, Women and Children's Health Research Institute, University of Alberta, Edmonton, Canada
| | - Edward C Deehan
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada
| | - Naomi Hotte
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Karen L Madsen
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Maitreyi Raman
- Department of Medicine, University of Calgary, Calgary, AB, Canada
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Abstract
How microbial metabolism is translated into cellular reproduction under energy-limited settings below the seafloor over long timescales is poorly understood. Here, we show that microbial abundance increases an order of magnitude over a 5 million-year-long sequence in anoxic subseafloor clay of the abyssal North Atlantic Ocean. This increase in biomass correlated with an increased number of transcribed protein-encoding genes that included those involved in cytokinesis, demonstrating that active microbial reproduction outpaces cell death in these ancient sediments. Metagenomes, metatranscriptomes, and 16S rRNA gene sequencing all show that the actively reproducing community was dominated by the candidate phylum "Candidatus Atribacteria," which exhibited patterns of gene expression consistent with fermentative, and potentially acetogenic, metabolism. "Ca. Atribacteria" dominated throughout the 8 million-year-old cored sequence, despite the detection limit for gene expression being reached in 5 million-year-old sediments. The subseafloor reproducing "Ca. Atribacteria" also expressed genes encoding a bacterial microcompartment that has potential to assist in secondary fermentation by recycling aldehydes and, thereby, harness additional power to reduce ferredoxin and NAD+ Expression of genes encoding the Rnf complex for generation of chemiosmotic ATP synthesis were also detected from the subseafloor "Ca Atribacteria," as well as the Wood-Ljungdahl pathway that could potentially have an anabolic or catabolic function. The correlation of this metabolism with cytokinesis gene expression and a net increase in biomass over the million-year-old sampled interval indicates that the "Ca Atribacteria" can perform the necessary catabolic and anabolic functions necessary for cellular reproduction, even under energy limitation in millions-of-years-old anoxic sediments.IMPORTANCE The deep subseafloor sedimentary biosphere is one of the largest ecosystems on Earth, where microbes subsist under energy-limited conditions over long timescales. It remains poorly understood how mechanisms of microbial metabolism promote increased fitness in these settings. We discovered that the candidate bacterial phylum "Candidatus Atribacteria" dominated a deep-sea subseafloor ecosystem, where it exhibited increased transcription of genes associated with acetogenic fermentation and reproduction in million-year-old sediment. We attribute its improved fitness after burial in the seabed to its capabilities to derive energy from increasingly oxidized metabolites via a bacterial microcompartment and utilize a potentially reversible Wood-Ljungdahl pathway to help meet anabolic and catabolic requirements for growth. Our findings show that "Ca Atribacteria" can perform all the necessary catabolic and anabolic functions necessary for cellular reproduction, even under energy limitation in anoxic sediments that are millions of years old.
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Microbial production of poly(3-hydroxybutyrate) from volatile fatty acids using the marine bacterium Neptunomonas concharum. ACTA ACUST UNITED AC 2020. [DOI: 10.1016/j.biteb.2020.100439] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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41
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Bohnenkamp AC, Kruis AJ, Mars AE, Wijffels RH, van der Oost J, Kengen SWM, Weusthuis RA. Multilevel optimisation of anaerobic ethyl acetate production in engineered Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:65. [PMID: 32280373 PMCID: PMC7137189 DOI: 10.1186/s13068-020-01703-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 03/25/2020] [Indexed: 05/05/2023]
Abstract
BACKGROUND Ethyl acetate is a widely used industrial solvent that is currently produced by chemical conversions from fossil resources. Several yeast species are able to convert sugars to ethyl acetate under aerobic conditions. However, performing ethyl acetate synthesis anaerobically may result in enhanced production efficiency, making the process economically more viable. RESULTS We engineered an E. coli strain that is able to convert glucose to ethyl acetate as the main fermentation product under anaerobic conditions. The key enzyme of the pathway is an alcohol acetyltransferase (AAT) that catalyses the formation of ethyl acetate from acetyl-CoA and ethanol. To select a suitable AAT, the ethyl acetate-forming capacities of Atf1 from Saccharomyces cerevisiae, Eat1 from Kluyveromyces marxianus and Eat1 from Wickerhamomyces anomalus were compared. Heterologous expression of the AAT-encoding genes under control of the inducible LacI/T7 and XylS/Pm promoters allowed optimisation of their expression levels. CONCLUSION Engineering efforts on protein and fermentation level resulted in an E. coli strain that anaerobically produced 42.8 mM (3.8 g/L) ethyl acetate from glucose with an unprecedented efficiency, i.e. 0.48 C-mol/C-mol or 72% of the maximum pathway yield.
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Affiliation(s)
- Anna C. Bohnenkamp
- Bioprocess Engineering, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Aleksander J. Kruis
- Bioprocess Engineering, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Astrid E. Mars
- Biobased Products, Wageningen University and Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Rene H. Wijffels
- Bioprocess Engineering, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
- Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway
| | - John van der Oost
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Servé W. M. Kengen
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Ruud A. Weusthuis
- Bioprocess Engineering, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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Open microbiome dominated by Clostridium and Eubacterium converts methanol into i-butyrate and n-butyrate. Appl Microbiol Biotechnol 2020; 104:5119-5131. [PMID: 32248436 DOI: 10.1007/s00253-020-10551-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 02/29/2020] [Accepted: 03/15/2020] [Indexed: 12/14/2022]
Abstract
Isobutyrate (i-butyrate) is a versatile platform chemical, whose acid form is used as a precursor of plastic and emulsifier. It can be produced microbially either using genetically engineered organisms or via microbiomes, in the latter case starting from methanol and short-chain carboxylates. This opens the opportunity to produce i-butyrate from non-sterile feedstocks. Little is known on the ecology and process conditions leading to i-butyrate production. In this study, we steered i-butyrate production in a bioreactor fed with methanol and acetate under various conditions, achieving maximum i-butyrate productivity of 5.0 mM day-1, with a concurrent production of n-butyrate of 7.9 mM day-1. The production of i-butyrate was reversibly inhibited by methanogenic inhibitor 2-bromoethanesulfonate. The microbial community data revealed the co-dominance of two major OTUs during co-production of i-butyrate and n-butyrate in two distinctive phases throughout a period of 54 days and 28 days, respectively. The cross-comparison of product profile with microbial community composition suggests that the relative abundance of Clostridium sp. over Eubacterium sp. is correlated with i-butyrate productivity over n-butyrate productivity.
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Accumulation of high-value bioproducts in planta can improve the economics of advanced biofuels. Proc Natl Acad Sci U S A 2020; 117:8639-8648. [PMID: 32220956 PMCID: PMC7165473 DOI: 10.1073/pnas.2000053117] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cellulosic biofuels have not yet reached cost parity with conventional petroleum fuels. One strategy to address this challenge is to generate valuable coproducts alongside biofuels. Engineering bioenergy crops to generate value-added bioproducts in planta can reduce input requirements relative to microbial chassis and skip costly deconstruction and conversion steps. Although rapid progress has been made in plant metabolic engineering, there has been no systematic analysis devoted to quantifying the impact of such engineered bioenergy crops on biorefinery economics. Here, we provide new insights into how bioproduct accumulation in planta affects biofuel selling prices. We present the range of bioproduct selling prices and accumulation rates needed to compensate for additional extraction steps and reach a target $2.50/gal minimum biofuel selling price. Coproduction of high-value bioproducts at biorefineries is a key factor in making biofuels more cost-competitive. One strategy for generating coproducts is to directly engineer bioenergy crops to accumulate bioproducts in planta that can be fractionated and recovered at biorefineries. Here, we develop quantitative insights into the relationship between bioproduct market value and target accumulation rates by investigating a set of industrially relevant compounds already extracted from plant sources with a wide range of market prices and applications, including <$10/kg (limonene, latex, and polyhydroxybutyrate [PHB]), $10 to $100/kg (cannabidiol), and >$100/kg (artemisinin). These compounds are used to identify a range of mass fraction thresholds required to achieve net economic benefits for biorefineries and the additional amounts needed to reach a target $2.50/gal biofuel selling price, using cellulosic ethanol production as a test case. Bioproduct market prices and recovery costs determine the accumulation threshold; we find that moderate- to high-value compounds (i.e., cannabidiol and artemisinin) offer net economic benefits at accumulation rates of just 0.01% dry weight (dwt) to 0.02 dwt%. Lower-value compounds, including limonene, latex, and PHB, require at least an order-of-magnitude greater accumulation to overcome additional extraction and recovery costs (0.3 to 1.2 dwt%). We also find that a diversified approach is critical. For example, global artemisinin demand could be met with fewer than 10 biorefineries, while global demand for latex is equivalent to nearly 180 facilities. Our results provide a roadmap for future plant metabolic engineering efforts aimed at increasing the value derived from bioenergy crops.
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Lee JW, Trinh CT. Towards renewable flavors, fragrances, and beyond. Curr Opin Biotechnol 2020; 61:168-180. [PMID: 31986468 DOI: 10.1016/j.copbio.2019.12.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 12/01/2019] [Accepted: 12/17/2019] [Indexed: 02/08/2023]
Abstract
Esters constitute a large space of unique molecules with broad range of applications as flavors, fragrances, pharmaceuticals, cosmetics, green solvents, and advanced biofuels. Global demand of natural esters in food, household cleaner, personal care, and perfume industries is increasing while the ester supply from natural sources has been limited. Development of novel microbial cell factories for ester production from renewable feedstocks can potentially provide an alternative and sustainable source of natural esters and hence help fulfill growing demand. Here, we highlight recent advances in microbial production of esters and provide perspectives for improving its economic feasibility. As the field matures, microbial ester production platforms will enable renewable and sustainable production of flavors and fragrances, and open new market opportunities beyond what nature can offer.
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Affiliation(s)
- Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Cong T Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, USA; Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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Bioderivatization as a concept for renewable production of chemicals that are toxic or poorly soluble in the liquid phase. Proc Natl Acad Sci U S A 2020; 117:1404-1413. [PMID: 31915296 PMCID: PMC6983404 DOI: 10.1073/pnas.1914069117] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Microorganisms can be rationally engineered to convert CO2 and H2O into chemicals, replacing those made from fossil fuels today. Sometimes such chemicals are poorly soluble in water or negatively affect the growth of the microorganism, resulting in cost-inefficient manufacturing. In nature, this problem is often solved by converting incompatible chemicals into those more compatible with the host and/or environment. Inspired by this, we propose a similar strategy for engineered biotechnology, whereby biochemical conversion inside the microorganism is followed by chemical reversal once outside. The principle was demonstrated with 1-octanol by implementing two different conversion methods in two different species, showing enhanced bioproduction in most cases. The approach may stimulate commercialization of sustainable and renewable production of chemicals. Bio-based production technologies may complement or replace petroleum-based production of chemicals, but they face a number of technical challenges, including product toxicity and/or water insolubility. Plants and microorganisms naturally biosynthesize chemicals that often are converted into derivatives with reduced toxicity or enhanced solubility. Inspired by this principle, we propose a bioderivatization strategy for biotechnological chemicals production, defined as purposeful biochemical derivatization of intended target molecules. As proof of principle, the effects of hydrophobic (e.g., esterification) and hydrophilic (e.g., glycosylation) bioderivatization strategies on the biosynthesis of a relatively toxic and poorly soluble chemical, 1-octanol, were evaluated in Escherichia coli and Synechocystis sp. PCC 6803. The 1-octanol pathway was first optimized to reach product titers at which the host displayed symptoms of toxicity. Solvent overlay used to capture volatile products partially masked product toxicity. Regardless of whether solvent overlay was used, most strains with bioderivatization had a higher molar product titer and product yield, as well as improved cellular growth and glucose consumption, compared with strains without bioderivatization. The positive effect on bioproduction was observed with both the hydrophobic and hydrophilic strategies. Interestingly, in several combinations of genotype/induction strength, bioderivatization had a positive effect on productivity without any apparent effect on growth. We attribute this to enhanced product solubility in the aqueous or solvent fraction of the bioreactor liquid phase (depending on the derivative and medium used), with consequent enhanced product removal. Overall, under most conditions, a benefit of bioproduction was observed, and the bioderivatization strategy could be considered for other similar chemicals as well.
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Kruis AJ, Bohnenkamp AC, Patinios C, van Nuland YM, Levisson M, Mars AE, van den Berg C, Kengen SW, Weusthuis RA. Microbial production of short and medium chain esters: Enzymes, pathways, and applications. Biotechnol Adv 2019; 37:107407. [DOI: 10.1016/j.biotechadv.2019.06.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/24/2019] [Accepted: 06/09/2019] [Indexed: 12/12/2022]
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Lee JW, Trinh CT. Microbial biosynthesis of lactate esters. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:226. [PMID: 31548868 PMCID: PMC6753613 DOI: 10.1186/s13068-019-1563-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 09/07/2019] [Indexed: 05/18/2023]
Abstract
BACKGROUND Green organic solvents such as lactate esters have broad industrial applications and favorable environmental profiles. Thus, manufacturing and use of these biodegradable solvents from renewable feedstocks help benefit the environment. However, to date, the direct microbial biosynthesis of lactate esters from fermentable sugars has not yet been demonstrated. RESULTS In this study, we present a microbial conversion platform for direct biosynthesis of lactate esters from fermentable sugars. First, we designed a pyruvate-to-lactate ester module, consisting of a lactate dehydrogenase (ldhA) to convert pyruvate to lactate, a propionate CoA-transferase (pct) to convert lactate to lactyl-CoA, and an alcohol acyltransferase (AAT) to condense lactyl-CoA and alcohol(s) to make lactate ester(s). By generating a library of five pyruvate-to-lactate ester modules with divergent AATs, we screened for the best module(s) capable of producing a wide range of linear, branched, and aromatic lactate esters with an external alcohol supply. By co-introducing a pyruvate-to-lactate ester module and an alcohol (i.e., ethanol, isobutanol) module into a modular Escherichia coli (chassis) cell, we demonstrated for the first time the microbial biosynthesis of ethyl and isobutyl lactate esters directly from glucose. In an attempt to enhance ethyl lactate production as a proof-of-study, we re-modularized the pathway into (1) the upstream module to generate the ethanol and lactate precursors and (2) the downstream module to generate lactyl-CoA and condense it with ethanol to produce the target ethyl lactate. By manipulating the metabolic fluxes of the upstream and downstream modules through plasmid copy numbers, promoters, ribosome binding sites, and environmental perturbation, we were able to probe and alleviate the metabolic bottlenecks by improving ethyl lactate production by 4.96-fold. We found that AAT is the most rate-limiting step in biosynthesis of lactate esters likely due to its low activity and specificity toward the non-natural substrate lactyl-CoA and alcohols. CONCLUSIONS We have successfully established the biosynthesis pathway of lactate esters from fermentable sugars and demonstrated for the first time the direct fermentative production of lactate esters from glucose using an E. coli modular cell. This study defines a cornerstone for the microbial production of lactate esters as green solvents from renewable resources with novel industrial applications.
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Affiliation(s)
- Jong-Won Lee
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Cong T. Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Dr., DO#432, Knoxville, TN 37996 USA
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48
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Wang L, Chauliac D, Moritz BE, Zhang G, Ingram LO, Shanmugam KT. Metabolic engineering of Escherichia coli for the production of butyric acid at high titer and productivity. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:62. [PMID: 30949238 PMCID: PMC6429758 DOI: 10.1186/s13068-019-1408-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 03/13/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Several anaerobic bacteria produce butyric acid, a commodity chemical with use in chemical, pharmaceutical, food and feed industries, using complex media with acetate as a co-product. Butyrate titer of various recombinant Escherichia coli did not exceed 10 g l-1 in batch fermentations in any of the media tested. RESULTS A recombinant E. coli (strain LW393) that produced butyrate as the major fermentation product was constructed with genes from E. coli, Clostridium acetobutylicum and Treponema denticola. Strain LW393 produced 323 ± 6 mM (28.4 ± 0.4 g l-1) butyric acid in batch fermentations in mineral salt medium with glucose as C source at a yield of 0.37 ± 0.01 g (g glucose consumed)-1. Butyrate accounted for 90% of the total products produced by the culture. Supplementing this medium with yeast extract further increased butyric acid titer to 375 ± 4 mM. Average volumetric productivity of butyrate with xylose as C source was 0.89 ± 0.07 g l-1 h-1. CONCLUSIONS The butyrate titer reported in this study is about 2.5-3-times higher than the values reported for other recombinant E. coli and this is achieved in mineral salt medium with an expectation of lower purification and production cost of butyrate.
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Affiliation(s)
- Liang Wang
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611 USA
| | - Diane Chauliac
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611 USA
- Present Address: Galactic, Brussels, Belgium
| | - Brelan E. Moritz
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611 USA
| | - Guimin Zhang
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611 USA
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Science, Hubei University, Wuhan, 430062 China
| | - Lonnie O. Ingram
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611 USA
| | - K. T. Shanmugam
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611 USA
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Alalwan HA, Alminshid AH, Aljaafari HA. Promising evolution of biofuel generations. Subject review. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.ref.2018.12.006] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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50
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Chakraborty S, Rene ER, Lens PNL, Veiga MC, Kennes C. Enrichment of a solventogenic anaerobic sludge converting carbon monoxide and syngas into acids and alcohols. BIORESOURCE TECHNOLOGY 2019; 272:130-136. [PMID: 30321830 DOI: 10.1016/j.biortech.2018.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 09/29/2018] [Accepted: 10/01/2018] [Indexed: 06/08/2023]
Abstract
An anaerobic granular sludge was acclimatized to utilise CO in a continuously gas-fed stirred tank bioreactor by applying operating conditions expected to stimulate solventogenesis, i.e. the production of alcohols, and allowing to enrich for solventogenic populations. A cycle of high (6.2) and low (4.9) pH was applied in order to produce volatile fatty acids first at high pH, followed by their bioconversion into alcohols at low pH. The addition of yeast extract stimulated biomass growth, but not necessarily solventogenesis. The highest concentrations of metabolites achieved were 6.18 g/L acetic acid (30th day), 1.18 g/L butyric acid (28th day), and 0.423 g/L hexanoic acid (32nd day). Subsequently, acids were metabolized at lower pH, producing alcohols at concentrations of 11.1 g/L ethanol (43rd day), 1.8 g/L butanol (41st day) and 1.46 g/L hexanol (42nd day), confirming the successful enrichment strategy. Similarly, the enriched sludge could also convert syngas into acids and alcohols.
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Affiliation(s)
- Samayita Chakraborty
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), University of La Coruña (UDC), E-15008 La Coruña, Spain; UNESCO-IHE Institute for Water Education, Westvest 7, P.O. Box 3015, NL-2611 AX Delft, The Netherlands
| | - Eldon R Rene
- UNESCO-IHE Institute for Water Education, Westvest 7, P.O. Box 3015, NL-2611 AX Delft, The Netherlands
| | - Piet N L Lens
- UNESCO-IHE Institute for Water Education, Westvest 7, P.O. Box 3015, NL-2611 AX Delft, The Netherlands
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), University of La Coruña (UDC), E-15008 La Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), University of La Coruña (UDC), E-15008 La Coruña, Spain.
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