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Jilani SB. Deletion of yghZ in Escherichia coli promotes growth in presence of furfural with xylose as carbon source. FEMS Microbiol Lett 2024; 371:fnae028. [PMID: 38664064 DOI: 10.1093/femsle/fnae028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 02/23/2024] [Accepted: 04/24/2024] [Indexed: 05/15/2024] Open
Abstract
Thermo-acidic pretreatment of lignocellulosic biomass is required to make it amenable to microbial metabolism and results in generation of furfural due to breakdown of pentose sugars. Furfural is toxic to microbial metabolism and results in reduced microbial productivity and increased production costs. This study asks if deletion of yghZ gene which encodes a NADPH-dependent aldehyde reductase enzyme results in improved furfural tolerance in Escherichia coli host. The ∆yghZ strain-SSK201-was tested for tolerance to furfural in presence of 5% xylose as a carbon source in AM1 minimal medium. At 96 h and in presence of 1.0 g/L furfural, the culture harboring strain SSK201 displayed 4.5-fold higher biomass, 2-fold lower furfural concentration and 15.75-fold higher specific growth rate (µ) as compared to the parent strain SSK42. The furfural tolerance advantage of SSK201 was retained when the carbon source was switched to glucose in AM1 medium and was lost in rich LB medium. The findings have potential to be scaled up to a hydrolysate culture medium, which contains furan inhibitors and lack nutritionally rich components, under bioreactor cultivation and observe growth advantage of the ∆yghZ host. It harbors potential to generate robust industrial strains which can convert lignocellulosic carbon into metabolites of interest in a cost-efficient manner.
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Affiliation(s)
- S Bilal Jilani
- Institute of Biotechnology, Amity University, Manesar, Haryana 122413, India
- Microbial Engineering Group, International Center for Genetic Engineering and Biotechnology, New Delhi 110067, India
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Jilani SB, Olson DG. Mechanism of furfural toxicity and metabolic strategies to engineer tolerance in microbial strains. Microb Cell Fact 2023; 22:221. [PMID: 37891678 PMCID: PMC10612203 DOI: 10.1186/s12934-023-02223-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 10/05/2023] [Indexed: 10/29/2023] Open
Abstract
Lignocellulosic biomass represents a carbon neutral cheap and versatile source of carbon which can be converted to biofuels. A pretreatment step is frequently used to make the lignocellulosic carbon bioavailable for microbial metabolism. Dilute acid pretreatment at high temperature and pressure is commonly utilized to efficiently solubilize the pentose fraction by hydrolyzing the hemicellulose fibers and the process results in formation of furans-furfural and 5-hydroxymethyl furfural-and other inhibitors which are detrimental to metabolism. The presence of inhibitors in the medium reduce productivity of microbial biocatalysts and result in increased production costs. Furfural is the key furan inhibitor which acts synergistically along with other inhibitors present in the hydrolysate. In this review, the mode of furfural toxicity on microbial metabolism and metabolic strategies to increase tolerance is discussed. Shared cellular targets between furfural and acetic acid are compared followed by discussing further strategies to engineer tolerance. Finally, the possibility to use furfural as a model inhibitor of dilute acid pretreated lignocellulosic hydrolysate is discussed. The furfural tolerant strains will harbor an efficient lignocellulosic carbon to pyruvate conversion mechanism in presence of stressors in the medium. The pyruvate can be channeled to any metabolite of interest by appropriate modulation of downstream pathway of interest. The aim of this review is to emphasize the use of hydrolysate as a carbon source for bioproduction of biofuels and other compounds of industrial importance.
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Affiliation(s)
- S Bilal Jilani
- Thayer School of Engineering, Dartmouth College, 15 Thayer Drive, Hanover, NH, 03755, USA.
| | - Daniel G Olson
- Thayer School of Engineering, Dartmouth College, 15 Thayer Drive, Hanover, NH, 03755, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
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Improved furfural tolerance in Escherichia coli mediated by heterologous NADH-dependent benzyl alcohol dehydrogenases. Biochem J 2022; 479:1045-1058. [PMID: 35502833 PMCID: PMC9162472 DOI: 10.1042/bcj20210811] [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: 11/26/2021] [Revised: 04/21/2022] [Accepted: 05/03/2022] [Indexed: 11/18/2022]
Abstract
While lignocellulose is a promising source of renewable sugars for microbial fermentations, the presence of inhibitory compounds in typical lignocellulosic feedstocks, such as furfural, has hindered their utilisation. In Escherichia coli, a major route of furfural toxicity is the depletion of NADPH pools due to its use as a substrate by the YqhD enzyme that reduces furfural to its less toxic alcohol form. Here, we examine the potential of exploiting benzyl alcohol dehydrogenases as an alternative means to provide this same catalytic function but using the more abundant reductant NADH, as a strategy to increase the capacity for furfural removal. We determine the biochemical properties of three of these enzymes, from Pseudomonas putida, Acinetobacter calcoaceticus, and Burkholderia ambifaria, which all demonstrate furfural reductase activity. Furthermore, we show that the P. putida and B. ambifaria enzymes are able to provide substantial increases in furfural tolerance in vivo, by allowing more rapid conversion to furfuryl alcohol and resumption of growth. The study demonstrates that methods to seek alternative cofactor dependent enzymes can improve the intrinsic robustness of microbial chassis to feedstock inhibitors.
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Jilani SB, Prasad R, Yazdani SS. Overexpression of Oxidoreductase YghA Confers Tolerance of Furfural in Ethanologenic Escherichia coli Strain SSK42. Appl Environ Microbiol 2021; 87:e0185521. [PMID: 34586907 PMCID: PMC8579976 DOI: 10.1128/aem.01855-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 09/21/2021] [Indexed: 02/02/2023] Open
Abstract
Furfural is a common furan inhibitor formed due to dehydration of pentose sugars, like xylose, and acts as an inhibitor of microbial metabolism. Overexpression of NADH-specific FucO and deletion of NADPH-specific YqhD had been a successful strategy in the past in conferring tolerance against furfural in Escherichia coli, which highlights the importance of oxidoreductases in conferring tolerance against furfural. In a screen consisting of various oxidoreductases, dehydrogenases, and reductases, we identified the yghA gene as an overexpression target to confer tolerance against furfural. YghA preferably used NADH as a cofactor and had an apparent Km value of 0.03 mM against furfural. In the presence of 1 g liter-1 furfural and 10% xylose (wt/vol), yghA overexpression in an ethanologenic E. coli strain SSK42 resulted in an ethanol efficiency of ∼97%, with a 5.3-fold increase in ethanol titers compared to the control. YghA also exhibited activity against the less toxic inhibitor 5-hydroxymethyl furfural, which is formed due to dehydration of hexose sugars, and thus is a formidable target for overexpression in ethanologenic strain for fermentation of sugars in biomass hydrolysate. IMPORTANCE Lignocellulosic biomass represents an inexhaustible source of carbon for second-generation biofuels. Thermo-acidic pretreatment of biomass is performed to loosen the lignocellulosic fibers and make the carbon bioavailable for microbial metabolism. The pretreatment process also results in the formation of inhibitors that inhibit microbial metabolism and increase production costs. Furfural is a potent furan inhibitor that increases the toxicity of other inhibitors present in the hydrolysate. Thus, it is desirable to engineer furfural tolerance in E. coli for efficient fermentation of hydrolysate sugars.
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Affiliation(s)
- S. Bilal Jilani
- Microbial Engineering Group, International Center for Genetic Engineering and Biotechnology, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- Institute of Biotechnology, Amity University, Manesar, Haryana, India
| | - Rajendra Prasad
- Institute of Biotechnology, Amity University, Manesar, Haryana, India
| | - Syed Shams Yazdani
- Microbial Engineering Group, International Center for Genetic Engineering and Biotechnology, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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Machas M, Kurgan G, Abed OA, Shapiro A, Wang X, Nielsen D. Characterizing Escherichia coli's transcriptional response to different styrene exposure modes reveals novel toxicity and tolerance insights. J Ind Microbiol Biotechnol 2021; 48:kuab019. [PMID: 33640981 PMCID: PMC9138201 DOI: 10.1093/jimb/kuab019] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 02/18/2021] [Indexed: 11/24/2022]
Abstract
The global transcriptional response of Escherichia coli to styrene and potential influence of exposure source was determined by performing RNA sequencing (RNA-seq) analysis on both styrene-producing and styrene-exposed cells. In both cases, styrene exposure appears to cause both cell envelope and DNA damage, to which cells respond by down-regulating key genes/pathways involved in DNA replication, protein production, and cell wall biogenesis. Among the most significantly up-regulated genes were those involved with phage shock protein response (e.g. pspABCDE/G), general stress regulators (e.g. marA, rpoH), and membrane-altering genes (notably, bhsA, ompR, ldtC), whereas efflux transporters were, surprisingly, unaffected. Subsequent studies with styrene addition demonstrate how strains lacking ompR [involved in controlling outer membrane (OM) composition/osmoregulation] or any of tolQ, tolA, or tolR (involved in OM constriction) each displayed over 40% reduced growth relative to wild-type. Conversely, despite reducing basal fitness, overexpression of plsX (involved in phospholipid biosynthesis) led to 70% greater growth when styrene exposed. These collective differences point to the likely importance of OM properties in controlling native styrene tolerance. Overall, the collective behaviours suggest that, regardless of source, prolonged exposure to inhibitory styrene levels causes cells to shift from'growth mode' to 'survival mode', redistributing cellular resources to fuel native tolerance mechanisms.
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Affiliation(s)
- Michael Machas
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287-6106, USA
| | - Gavin Kurgan
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-6106, USA
| | - Omar A Abed
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287-6106, USA
| | - Alyssa Shapiro
- Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Xuan Wang
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-6106, USA
| | - David Nielsen
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287-6106, USA
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Obruca S, Sedlacek P, Koller M. The underexplored role of diverse stress factors in microbial biopolymer synthesis. BIORESOURCE TECHNOLOGY 2021; 326:124767. [PMID: 33540213 DOI: 10.1016/j.biortech.2021.124767] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 06/12/2023]
Abstract
Polyhydroxyalkanoates (PHA) are microbial polyesters which, apart from their primary storage role, enhance the stress robustness of PHA accumulating cells against various stressors. PHA also represent interesting alternatives to petrochemical polymers, which can be produced from renewable resources employing approaches of microbial biotechnology. During biotechnological processes, bacterial cells are exposed to various stressor factors such as fluctuations in temperature, osmolarity, pH-value, elevated pressure or the presence of microbial inhibitors. This review summarizes how PHA helps microbial cells to cope with biotechnological process-relevant stressors and, vice versa, how various stress conditions can affect PHA production processes. The review suggests a fundamentally new strategy for PHA production: the fine-tuned exposure to selected stressors, which might be used to boost PHA production and even to tailor their structure.
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Affiliation(s)
- Stanislav Obruca
- Faculty of Chemistry, Brno University of Technology, Purkynova 118, 612 00 Brno, Czech Republic.
| | - Petr Sedlacek
- Faculty of Chemistry, Brno University of Technology, Purkynova 118, 612 00 Brno, Czech Republic
| | - Martin Koller
- Institute of Chemistry, NAWI Graz, University of Graz, Heinrichstrasse 28/VI, 8010 Graz, Austria; ARENA Arbeitsgemeinschaft für Ressourcenschonende & Nachhaltige Technologien, Inffeldgasse 21b, 11 8010 Graz, Austria
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Jilani SB, Dev C, Eqbal D, Jawed K, Prasad R, Yazdani SS. Deletion of pgi gene in E. coli increases tolerance to furfural and 5-hydroxymethyl furfural in media containing glucose-xylose mixture. Microb Cell Fact 2020; 19:153. [PMID: 32723338 PMCID: PMC7389444 DOI: 10.1186/s12934-020-01414-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 07/20/2020] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Furfural and 5-hydroxymethyl furfural (5-HMF) are key furan inhibitors that are generated due to breakdown of lignocellulosic sugars at high temperature and acidic treatment conditions. Both furfural and 5-HMF act in a synergistic manner to inhibit microbial metabolism and resistance to both is a desirable characteristic for efficient conversion of lignocellulosic carbon to ethanol. Genetic manipulations targeted toward increasing cellular NADPH pools have successfully imparted tolerance against furfural and 5-HMF. In present study, deletion of pgi gene as a strategy to augment carbon flow through pentose phosphate pathway (PPP) was studied in ethanologenic Escherichia coli strain SSK101 to impart tolerance towards either furfural or 5-HMFor both inhibitors together. RESULTS A key gene of EMP pathway, pgi, was deleted in an ethanologenic E. coli strain SSK42 to yield strain SSK101. In presence of 1 g/L furfural in minimal AM1 media, the rate of biomass formation for strain SSK101 was up to 1.9-fold higher as compared to parent SSK42 strain, and it was able to clear furfural in half the time. Tolerance to inhibitor was associated with glucose as carbon source and not xylose, and the tolerance advantage of SSK101 was neutralized in LB media. Bioreactor studies were performed under binary stress of furfural and 5-HMF (1 g/L each) and different glucose concentrations in a glucose-xylose mixture with final sugar concentration of 5.5%, mimicking major components of dilute acid treated biomass hydrolysate. In the mixture having 6 g/L and 12 g/L glucose, SSK101 strain produced ~ 18 g/L and 20 g/L ethanol, respectively. Interestingly, the maximum ethanol productivity was better at lower glucose load with 0.46 g/(L.h) between 96 and 120 h, as compared to higher glucose load where it was 0.33 g/(L.h) between 144 and 168 h. Importantly, parent strain SSK42 did not exhibit significant metabolic activity under similar conditions of inhibitor load and sugar concentration. CONCLUSIONS E. coli strain SSK101 with pgi deletion had enhanced tolerance against both furfural and 5-HMF, which was associated with presence of glucose in media. Strain SSK101 also had improved fermentation characteristics under both hyperosmotic as well as binary stress of furfural and 5-HMF in media containing glucose-xylose mixture.
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Affiliation(s)
- Syed Bilal Jilani
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- Institute of Biotechnology, Amity University, Manesar, Haryana India
| | - Chandra Dev
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Danish Eqbal
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Kamran Jawed
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- Present Address: Biodiscovery Institute, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Rajendra Prasad
- Institute of Biotechnology, Amity University, Manesar, Haryana India
| | - Syed Shams Yazdani
- Microbial Engineering Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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Zhang J, Zhang X, Mao Y, Jin B, Guo Y, Wang Z, Chen T. Substrate profiling and tolerance testing of Halomonas TD01 suggest its potential application in sustainable manufacturing of chemicals. J Biotechnol 2020; 316:1-5. [PMID: 32311394 DOI: 10.1016/j.jbiotec.2020.04.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/10/2020] [Accepted: 04/13/2020] [Indexed: 01/19/2023]
Abstract
Halomonas TD01, which can grow under non-sterile and continuous processes at high pH and high salt concentrations, is a robust platform for PHA production from glucose. For extending other low-cost sustainable substrates and increasing the potential application in other value-added products, a better understanding of substrates utilization and chemicals tolerance is necessary. In this study, the substrate profiling of TD01 was analyzed via Biolog. Phenotype microarray results demonstrated that TD01 has a wide-ranging substrate spectrum and can utilize 140 of the 190 test compounds. Some cheap, abundant carbon sources, such as sodium acetate, glycerol, ethanol and lactate can well support the growth of TD01 in shake-flask, and are therefore suggested to be its alternative low-cost substrates for chemicals production in future. Furthermore, the tolerance of TD01 to various chemicals was tested. The results showed that the tolerability of TD01 to high concentrations of organic acid salts is prominent. When adding 75 g/L sodium acetate, 100 g/L succinic acid and 100 g/L itaconic acid in the medium, the growth rate reduced 56.14%, 52.63% and 47.37%, respectively. All these results highlight TD01 as a promising, next generation industrial workhorse in chemicals biomanufacturing from cheap organic acid salts.
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Affiliation(s)
- Jing Zhang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Xin Zhang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Yufeng Mao
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Biao Jin
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Yanmei Guo
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Zhiwen Wang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Tao Chen
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering of Ministry of Education, SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
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Shi A, Yomano LP, York SW, Zheng H, Shanmugam KT, Ingram LO. Chromosomal mutations in Escherichia coli that improve tolerance to nonvolatile side-products from dilute acid treatment of sugarcane bagasse. Biotechnol Bioeng 2019; 117:85-95. [PMID: 31612993 DOI: 10.1002/bit.27189] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/16/2019] [Accepted: 10/10/2019] [Indexed: 01/03/2023]
Abstract
Lignocellulosic biomass provides attractive nonfood carbohydrates for the production of ethanol, and dilute acid pretreatment is a biomass-independent process for access to these carbohydrates. However, this pretreatment also releases volatile and nonvolatile inhibitors of fermenting microorganisms. To identify unique gene products contributing to sensitivity/tolerance to nonvolatile inhibitors, ethanologenic Escherichia coli strain LY180 was adapted for growth in vacuum-treated sugarcane bagasse acid hydrolysate (VBHz) lacking furfural and other volatile inhibitors. A mutant, strain AQ15, obtained after approximately 500 generations of growth in VBHz, grew and fermented the sugars in a medium with 50% VBHz. Comparative genome sequence analysis of strains AQ15 and LY180 revealed 95 mutations in strain AQ15. Six of these mutations were also found in strain SL112, an independent inhibitor-tolerant derivative of strain LY180. Among these six mutations, null mutations in mdh and bacA were identified as contributing factors to VBHz tolerance in strain AQ15, based on the genetic and physiological analysis. The deletion of either gene in strain LY180 increased tolerance to VBHz from approximately 30-50% (vol/vol). Considering the location and physiological role of the two enzymes in the cell, it is likely that the two enzymes contribute to the VBHz sensitivity of ethanologenic E. coli by different mechanisms.
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Affiliation(s)
- Aiqin Shi
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida.,Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, Pennsylvania
| | - Lorraine P Yomano
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida
| | - Sean W York
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida
| | - Huabao Zheng
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida.,Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, College of Environmental and Resource Sciences, Zhejiang A & F University, Hangzhou, China
| | - Keelnatham T Shanmugam
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida
| | - Lonnie O Ingram
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida
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10
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Liu R, Liang L, Garst AD, Choudhury A, Nogué VSI, Beckham GT, Gill RT. Directed combinatorial mutagenesis of Escherichia coli for complex phenotype engineering. Metab Eng 2018; 47:10-20. [DOI: 10.1016/j.ymben.2018.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/02/2017] [Accepted: 02/20/2018] [Indexed: 01/19/2023]
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11
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Reynolds TS, Courtney CM, Erickson KE, Wolfe LM, Chatterjee A, Nagpal P, Gill RT. ROS mediated selection for increased NADPH availability in Escherichia coli. Biotechnol Bioeng 2017; 114:2685-2689. [PMID: 28710857 DOI: 10.1002/bit.26385] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 06/21/2017] [Accepted: 07/12/2017] [Indexed: 11/10/2022]
Abstract
The economical production of chemicals and fuels by microbial processes remains an intense area of interest in biotechnology. A key limitation in such efforts concerns the availability of key co-factors, in this case NADPH, required for target pathways. Many of the strategies pursued for increasing NADPH availability in Escherichia coli involve manipulations to the central metabolism, which can create redox imbalances and overall growth defects. In this study we used a reactive oxygen species based selection to search for novel methods of increasing NADPH availability. We report a loss of function mutation in the gene hdfR appears to increase NADPH availability in E. coli. Additionally, we show this excess NADPH can be used to improve the production of 3HP in E. coli.
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Affiliation(s)
- Thomas S Reynolds
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado
| | - Colleen M Courtney
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado
| | - Keesha E Erickson
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado
| | - Lisa M Wolfe
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, Colorado
| | - Anushree Chatterjee
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado.,BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado
| | - Prashant Nagpal
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado.,BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado.,Materials Science and Engineering, University of Colorado, Boulder, Boulder, Colorado
| | - Ryan T Gill
- Chemical and Biological Engineering, University of Colorado, Boulder, Colorado.,Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado
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12
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Catal T, Gover T, Yaman B, Droguetti J, Yilancioglu K. Hydrogen production profiles using furans in microbial electrolysis cells. World J Microbiol Biotechnol 2017; 33:115. [PMID: 28488198 DOI: 10.1007/s11274-017-2270-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Accepted: 04/22/2017] [Indexed: 10/19/2022]
Abstract
Microbial electrochemical cells including microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are novel biotechnological tools that can convert organic substances in wastewater or biomass into electricity or hydrogen. Electroactive microbial biofilms used in this technology have ability to transfer electrons from organic compounds to anodes. Evaluation of biofilm formation on anode is crucial for enhancing our understanding of hydrogen generation in terms of substrate utilization by microorganisms. In this study, furfural and hydroxymethylfurfural (HMF) were analyzed for hydrogen generation using single chamber membrane-free MECs (17 mL), and anode biofilms were also examined. MECs were inoculated with mixed bacterial culture enriched using chloroethane sulphonate. Hydrogen was succesfully produced in the presence of HMF, but not furfural. MECs generated similar current densities (5.9 and 6 mA/cm2 furfural and HMF, respectively). Biofilm samples obtained on the 24th and 40th day of cultivation using aromatic compounds were evaluated by using epi-fluorescent microscope. Our results show a correlation between biofilm density and hydrogen generation in single chamber MECs.
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Affiliation(s)
- Tunc Catal
- Department of Molecular Biology and Genetics, Uskudar University, Uskudar, 34662, Istanbul, Turkey.
- Biotechnology Application and Research Center, Uskudar University, Uskudar, 34662, Istanbul, Turkey.
| | - Tansu Gover
- Department of Molecular Biology and Genetics, Uskudar University, Uskudar, 34662, Istanbul, Turkey
| | - Bugra Yaman
- Department of Molecular Biology and Genetics, Uskudar University, Uskudar, 34662, Istanbul, Turkey
| | - Jessica Droguetti
- Department of Bioengineering, Uskudar University, Uskudar, 34662, Istanbul, Turkey
| | - Kaan Yilancioglu
- Department of Bioengineering, Uskudar University, Uskudar, 34662, Istanbul, Turkey
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Rau MH, Calero P, Lennen RM, Long KS, Nielsen AT. Genome-wide Escherichia coli stress response and improved tolerance towards industrially relevant chemicals. Microb Cell Fact 2016; 15:176. [PMID: 27737709 PMCID: PMC5064937 DOI: 10.1186/s12934-016-0577-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 10/03/2016] [Indexed: 01/17/2023] Open
Abstract
Background Economically viable biobased production of bulk chemicals and biofuels typically requires high product titers. During microbial bioconversion this often leads to product toxicity, and tolerance is therefore a critical element in the engineering of production strains. Results Here, a systems biology approach was employed to understand the chemical stress response of Escherichia coli, including a genome-wide screen for mutants with increased fitness during chemical stress. Twelve chemicals with significant production potential were selected, consisting of organic solvent-like chemicals (butanol, hydroxy-γ-butyrolactone, 1,4-butanediol, furfural), organic acids (acetate, itaconic acid, levulinic acid, succinic acid), amino acids (serine, threonine) and membrane-intercalating chemicals (decanoic acid, geraniol). The transcriptional response towards these chemicals revealed large overlaps of transcription changes within and between chemical groups, with functions such as energy metabolism, stress response, membrane modification, transporters and iron metabolism being affected. Regulon enrichment analysis identified key regulators likely mediating the transcriptional response, including CRP, RpoS, OmpR, ArcA, Fur and GadX. These regulators, the genes within their regulons and the above mentioned cellular functions therefore constitute potential targets for increasing E. coli chemical tolerance. Fitness determination of genome-wide transposon mutants (Tn-seq) subjected to the same chemical stress identified 294 enriched and 336 depleted mutants and experimental validation revealed up to 60 % increase in mutant growth rates. Mutants enriched in several conditions contained, among others, insertions in genes of the Mar-Sox-Rob regulon as well as transcription and translation related gene functions. Conclusions The combination of the transcriptional response and mutant screening provides general targets that can increase tolerance towards not only single, but multiple chemicals. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0577-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Martin Holm Rau
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark
| | - Patricia Calero
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark
| | - Rebecca M Lennen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark
| | - Katherine S Long
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark
| | - Alex T Nielsen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark.
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14
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Sandoval NR, Papoutsakis ET. Engineering membrane and cell-wall programs for tolerance to toxic chemicals: Beyond solo genes. Curr Opin Microbiol 2016; 33:56-66. [PMID: 27376665 DOI: 10.1016/j.mib.2016.06.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 06/09/2016] [Accepted: 06/16/2016] [Indexed: 10/21/2022]
Abstract
Metabolite toxicity in microbes, particularly at the membrane, remains a bottleneck in the production of fuels and chemicals. Under chemical stress, native adaptation mechanisms combat hyper-fluidization by modifying the phospholipids in the membrane. Recent work in fluxomics reveals the mechanism of how membrane damage negatively affects energy metabolism while lipidomic and transcriptomic analyses show that strains evolved to be tolerant maintain membrane fluidity under stress through a variety of mechanisms such as incorporation of cyclopropanated fatty acids, trans-unsaturated fatty acids, and upregulation of cell wall biosynthesis genes. Engineered strains with modifications made in the biosynthesis of fatty acids, peptidoglycan, and lipopolysaccharide have shown increased tolerance to exogenous stress as well as increased production of desired metabolites of industrial importance. We review recent advances in elucidation of mechanisms or toxicity and tolerance as well as efforts to engineer the bacterial membrane and cell wall.
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Affiliation(s)
- Nicholas R Sandoval
- Department of Chemical and Biomolecular Engineering, Molecular Biotechnology Laboratory, Delaware Biotechnology Institute, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA
| | - Eleftherios T Papoutsakis
- Department of Chemical and Biomolecular Engineering, Molecular Biotechnology Laboratory, Delaware Biotechnology Institute, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA.
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15
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Shi A, Zheng H, Yomano LP, York SW, Shanmugam KT, Ingram LO. Plasmidic Expression of nemA and yafC* Increased Resistance of Ethanologenic Escherichia coli LY180 to Nonvolatile Side Products from Dilute Acid Treatment of Sugarcane Bagasse and Artificial Hydrolysate. Appl Environ Microbiol 2016; 82:2137-2145. [PMID: 26826228 PMCID: PMC4807516 DOI: 10.1128/aem.03488-15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 01/24/2016] [Indexed: 11/20/2022] Open
Abstract
Hydrolysate-resistant Escherichia coli SL100 was previously isolated from ethanologenic LY180 after sequential transfers in AM1 medium containing a dilute acid hydrolysate of sugarcane bagasse and was used as a source of resistance genes. Many genes that affect tolerance to furfural, the most abundant inhibitor, have been described previously. To identify genes associated with inhibitors other than furfural, plasmid clones were selected in an artificial hydrolysate that had been treated with a vacuum to remove furfural. Two new resistance genes were discovered from Sau3A1 libraries of SL100 genomic DNA: nemA (N-ethylmaleimide reductase) and a putative regulatory gene containing a mutation in the coding region, yafC*. The presence of these mutations in SL100 was confirmed by sequencing. A single mutation was found in the upstream regulatory region of nemR (nemRA operon) in SL100. This mutation increased nemA activity 20-fold over that of the parent organism (LY180) in AM1 medium without hydrolysate and increased nemA mRNA levels >200-fold. Addition of hydrolysates induced nemA expression (mRNA and activity), in agreement with transcriptional control. NemA activity was stable in cell extracts (9 h, 37°C), eliminating a role for proteinase in regulation. LY180 with a plasmid expressing nemA or yafC* was more resistant to a vacuum-treated sugarcane bagasse hydrolysate and to a vacuum-treated artificial hydrolysate than LY180 with an empty-vector control. Neither gene affected furfural tolerance. The vacuum-treated hydrolysates inhibited the reduction of N-ethylmaleimide by NemA while also serving as substrates. Expression of the nemA or yafC* plasmid in LY180 doubled the rate of ethanol production from the vacuum-treated sugarcane bagasse hydrolysate.
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Affiliation(s)
- Aiqin Shi
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Huabao Zheng
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Lorraine P Yomano
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Sean W York
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Keelnatham T Shanmugam
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
| | - Lonnie O Ingram
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA
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16
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Identification of Genes Conferring Tolerance to Lignocellulose-Derived Inhibitors by Functional Selections in Soil Metagenomes. Appl Environ Microbiol 2015; 82:528-37. [PMID: 26546427 DOI: 10.1128/aem.02838-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/01/2015] [Indexed: 01/31/2023] Open
Abstract
The production of fuels or chemicals from lignocellulose currently requires thermochemical pretreatment to release fermentable sugars. These harsh conditions also generate numerous small-molecule inhibitors of microbial growth and fermentation, limiting production. We applied small-insert functional metagenomic selections to discover genes that confer microbial tolerance to these inhibitors, identifying both individual genes and general biological processes associated with tolerance to multiple inhibitory compounds. Having screened over 248 Gb of DNA cloned from 16 diverse soil metagenomes, we describe gain-of-function tolerance against acid, alcohol, and aldehyde inhibitors derived from hemicellulose and lignin, demonstrating that uncultured soil microbial communities hold tremendous genetic potential to address the toxicity of pretreated lignocellulose. We recovered genes previously known to confer tolerance to lignocellulosic inhibitors as well as novel genes that confer tolerance via unknown functions. For instance, we implicated galactose metabolism in overcoming the toxicity of lignin monomers and identified a decarboxylase that confers tolerance to ferulic acid; this enzyme has been shown to catalyze the production of 4-vinyl guaiacol, a valuable precursor to vanillin production. These metagenomic tolerance genes can enable the flexible design of hardy microbial catalysts, customized to withstand inhibitors abundant in specific bioprocessing applications.
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17
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Nieves LM, Panyon LA, Wang X. Engineering Sugar Utilization and Microbial Tolerance toward Lignocellulose Conversion. Front Bioeng Biotechnol 2015; 3:17. [PMID: 25741507 PMCID: PMC4332379 DOI: 10.3389/fbioe.2015.00017] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 02/04/2015] [Indexed: 12/22/2022] Open
Abstract
Production of fuels and chemicals through a fermentation-based manufacturing process that uses renewable feedstock such as lignocellulosic biomass is a desirable alternative to petrochemicals. Although it is still in its infancy, synthetic biology offers great potential to overcome the challenges associated with lignocellulose conversion. In this review, we will summarize the identification and optimization of synthetic biological parts used to enhance the utilization of lignocellulose-derived sugars and to increase the biocatalyst tolerance for lignocellulose-derived fermentation inhibitors. We will also discuss the ongoing efforts and future applications of synthetic integrated biological systems used to improve lignocellulose conversion.
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Affiliation(s)
- Lizbeth M Nieves
- School of Life Sciences, Arizona State University , Tempe, AZ , USA
| | - Larry A Panyon
- School of Life Sciences, Arizona State University , Tempe, AZ , USA
| | - Xuan Wang
- School of Life Sciences, Arizona State University , Tempe, AZ , USA
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18
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Liu W, Jiang R. Combinatorial and high-throughput screening approaches for strain engineering. Appl Microbiol Biotechnol 2015; 99:2093-104. [DOI: 10.1007/s00253-015-6400-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/09/2015] [Accepted: 01/10/2015] [Indexed: 12/31/2022]
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19
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Choi SY, Gong G, Park HS, Um Y, Sim SJ, Woo HM. Extreme furfural tolerance of a soil bacterium Enterobacter cloacae GGT036. J Biotechnol 2014; 193:11-3. [PMID: 25444876 DOI: 10.1016/j.jbiotec.2014.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/29/2014] [Accepted: 11/03/2014] [Indexed: 10/24/2022]
Abstract
Detoxification process of cellular inhibitors including furfural is essential for production of bio-based chemicals from lignocellulosic biomass. Here we isolated an extreme furfural-tolerant bacterium Enterobacter cloacae GGT036 from soil sample collected in Mt. Gwanak, Republic of Korea. Among isolated bacteria, only E. cloacae GGT036 showed cell growth with 35 mM furfural under aerobic culture. Compared to the maximal half inhibitory concentration (IC50) of well-known industrial strains Escherichia coli (24.9 mM furfural) and Corynebacterium glutamicum (10 mM furfural) based on the cell density, IC50 of E. cloacae GGT036 (47.7 mM) was significantly higher after 24 h, compared to E. coli and C. glutamicum. Since bacterial cell growth was exponentially inhibited depending on linearly increased furfural concentrations in the medium, we concluded that E. cloacae GGT036 is an extreme furfural-tolerant bacterium. Recently, the complete genome sequence of E. cloacae GGT036 was announced and this could provide an insight for engineering of E. cloacae GGT036 itself or other industrially relevant bacteria.
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Affiliation(s)
- Sun Young Choi
- Clean Energy Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Green School (Graduate School of Energy and Environment), 145 Anam-ro, Seongbuk-gu, Seoul, Republic of Korea
| | - Gyeongtaek Gong
- Clean Energy Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
| | - Hong-Sil Park
- Clean Energy Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Green School (Graduate School of Energy and Environment), 145 Anam-ro, Seongbuk-gu, Seoul, Republic of Korea
| | - Youngsoon Um
- Clean Energy Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Department of Clean Energy and Chemical Engineering, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 305-350, Republic of Korea
| | - Sang Jun Sim
- Green School (Graduate School of Energy and Environment), 145 Anam-ro, Seongbuk-gu, Seoul, Republic of Korea; Department of Chemical and Biological Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, Republic of Korea
| | - Han Min Woo
- Clean Energy Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea; Green School (Graduate School of Energy and Environment), 145 Anam-ro, Seongbuk-gu, Seoul, Republic of Korea; Department of Clean Energy and Chemical Engineering, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 305-350, Republic of Korea.
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20
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Tools for developing tolerance to toxic chemicals in microbial systems and perspectives on moving the field forward and into the industrial setting. Curr Opin Chem Eng 2014. [DOI: 10.1016/j.coche.2014.08.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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21
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Glebes TY, Sandoval NR, Gillis JH, Gill RT. Comparison of genome-wide selection strategies to identify furfural tolerance genes inEscherichia coli. Biotechnol Bioeng 2014; 112:129-40. [DOI: 10.1002/bit.25325] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 06/20/2014] [Accepted: 06/25/2014] [Indexed: 02/02/2023]
Affiliation(s)
- Tirzah Y. Glebes
- Department of Chemical and Biological Engineering; University of Colorado Boulder; Colorado
| | - Nicholas R. Sandoval
- Department of Chemical and Biological Engineering; University of Colorado Boulder; Colorado
| | - Jacob H. Gillis
- Department of Chemical and Biological Engineering; University of Colorado Boulder; Colorado
| | - Ryan T. Gill
- Department of Chemical and Biological Engineering; University of Colorado Boulder; Colorado
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22
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Polyamine transporters and polyamines increase furfural tolerance during xylose fermentation with ethanologenic Escherichia coli strain LY180. Appl Environ Microbiol 2014; 80:5955-64. [PMID: 25063650 DOI: 10.1128/aem.01913-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Expression of genes encoding polyamine transporters from plasmids and polyamine supplements increased furfural tolerance (growth and ethanol production) in ethanologenic Escherichia coli LY180 (in AM1 mineral salts medium containing xylose). This represents a new approach to increase furfural tolerance and may be useful for other organisms. Microarray comparisons of two furfural-resistant mutants (EMFR9 and EMFR35) provided initial evidence for the importance of polyamine transporters. Each mutant contained a single polyamine transporter gene that was upregulated over 100-fold (microarrays) compared to that in the parent LY180, as well as a mutation that silenced the expression of yqhD. Based on these genetic changes, furfural tolerance was substantially reconstructed in the parent, LY180. Deletion of potE in EMFR9 lowered furfural tolerance to that of the parent. Deletion of potE and puuP in LY180 also decreased furfural tolerance, indicating functional importance of the native genes. Of the 8 polyamine transporters (18 genes) cloned and tested, half were beneficial for furfural tolerance (PotE, PuuP, PlaP, and PotABCD). Supplementing AM1 mineral salts medium with individual polyamines (agmatine, putrescine, and cadaverine) also increased furfural tolerance but to a smaller extent. In pH-controlled fermentations, polyamine transporter plasmids were shown to promote the metabolism of furfural and substantially reduce the time required to complete xylose fermentation. This increase in furfural tolerance is proposed to result from polyamine binding to negatively charged cellular constituents such as nucleic acids and phospholipids, providing protection from damage by furfural.
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23
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Luhe AL, Lim CY, Gerken H, Wu J, Zhao H. Furfural and hydroxymethylfurfural tolerance in Escherichia coli ΔacrR regulatory mutants. Biotechnol Appl Biochem 2014; 62:32-6. [PMID: 24716991 DOI: 10.1002/bab.1232] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Accepted: 04/01/2014] [Indexed: 11/05/2022]
Abstract
The presence of the highly toxic furfural and hydroxymethylfurfural (HMF) in the hydrolysate of lignocellulosic biomass prompted the investigation of the Escherichia coli ΔacrR regulatory mutant for higher tolerance to these compounds, to facilitate the production of biofuels and biochemicals, and further biocatalytic conversions. In comparison with the parental strain, the regulatory mutant with the upregulated efflux pump AcrAB-TolC produced moderately better growth and higher tolerance to concentrations of furfural and HMF between 1 and 2 g L(-1) .
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Affiliation(s)
- Annette Lin Luhe
- Industrial Biotechnology Program, Institute of Chemical & Engineering Sciences, Agency for Science, Technology and Research (A*STAR), Jurong Island, Singapore
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