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Dai K, Qu C, Li X, Lan Y, Fu H, Wang J. Cofactor engineering in Thermoanaerobacterium aotearoense SCUT27 for maximizing ethanol yield and revealing an enzyme complex with high ferredoxin-NAD + reductase activity. BIORESOURCE TECHNOLOGY 2024; 402:130784. [PMID: 38701976 DOI: 10.1016/j.biortech.2024.130784] [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: 02/28/2024] [Revised: 04/03/2024] [Accepted: 04/30/2024] [Indexed: 05/06/2024]
Abstract
Thermoanaerobacterium aotearoense SCUT27 is a prominent producer of biofuels from lignocellulosic materials. To provide sufficient NAD(P)H for ethanol production, redox-related genes, including lactate dehydrogenase (ldh), redox-sensing transcriptional repressor (rex), and hydrogenase (hfsB), were knocked out. However, the growth of strain PRH (Δldh/Δrex/ΔhfsB) was suppressed due to the intracellular redox state imbalance with the increased NADH concentration. Coincidentally, when the Bcd-EtfAB (BCD) complex was overexpressed, the resulting strain PRH-B3 (Δldh/Δrex/ΔhfsB::BCD) grew rapidly and produced ethanol with a high yield. With lignocellulosic hydrolysates, PRH-BA (Δldh/Δrex/ΔhfsB::BCD::adhE) demonstrated high ethanol productivity and yield, reaching levels of 0.45-0.51 g/L/h and 0.46-0.53 g/g sugars, respectively. The study results shed light on the cofactor balance for cell stability and the high ferredoxin-NAD+ reductase activity of the BCD complex under an intracellular low redox state. They also provide an essential reference for developing strains for improved biofuel production.
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Affiliation(s)
- Kaiqun Dai
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Chunyun Qu
- College of Light Industry and Food Science, Guangdong Provincial Key Laboratory of Science and Technology of Lingnan Special Food Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China
| | - Xin Li
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Yang Lan
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Hongxin Fu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou 510006, China; State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510006, China.
| | - Jufang Wang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou 510006, China; State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510006, China.
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2
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Wang S, Jiang W, Jin X, Qi Q, Liang Q. Genetically encoded ATP and NAD(P)H biosensors: potential tools in metabolic engineering. Crit Rev Biotechnol 2023; 43:1211-1225. [PMID: 36130803 DOI: 10.1080/07388551.2022.2103394] [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: 12/08/2021] [Accepted: 05/08/2022] [Indexed: 11/03/2022]
Abstract
To date, many metabolic engineering tools and strategies have been developed, including tools for cofactor engineering, which is a common strategy for bioproduct synthesis. Cofactor engineering is used for the regulation of pyridine nucleotides, including NADH/NAD+ and NADPH/NADP+, and adenosine triphosphate/adenosine diphosphate (ATP/ADP), which is crucial for maintaining redox and energy balance. However, the intracellular levels of NADH/NAD+, NADPH/NADP+, and ATP/ADP cannot be monitored in real time using traditional methods. Recently, many biosensors for detecting, monitoring, and regulating the intracellular levels of NADH/NAD+, NADPH/NADP+, and ATP/ADP have been developed. Although cofactor biosensors have been mainly developed for use in mammalian cells, the potential application of cofactor biosensors in metabolic engineering in bacterial and yeast cells has received recent attention. Coupling cofactor biosensors with genetic circuits is a promising strategy in metabolic engineering for optimizing the production of biochemicals. In this review, we focus on the development of biosensors for NADH/NAD+, NADPH/NADP+, and ATP/ADP and the potential application of these biosensors in metabolic engineering. We also provide critical perspectives, identify current research challenges, and provide guidance for future research in this promising field.
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Affiliation(s)
- Sumeng Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Wei Jiang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xin Jin
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Qingsheng Qi
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
- CAS Key Lab of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Quanfeng Liang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
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Virdis B, Hoelzle R, Marchetti A, Boto ST, Rosenbaum MA, Blasco-Gómez R, Puig S, Freguia S, Villano M. Electro-fermentation: Sustainable bioproductions steered by electricity. Biotechnol Adv 2022; 59:107950. [PMID: 35364226 DOI: 10.1016/j.biotechadv.2022.107950] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 02/22/2022] [Accepted: 03/24/2022] [Indexed: 01/06/2023]
Abstract
The market of biobased products obtainable via fermentation processes is steadily increasing over the past few years, driven by the need to create a decarbonized economy. To date, industrial fermentation (IF) employs either pure or mixed microbial cultures (MMC) whereby the type of the microbial catalysts and the used feedstock affect metabolic pathways and, in turn, the type of product(s) generated. In many cases, especially when dealing with MMC, the economic viability of IF is hindered by factors such as the low attained product titer and selectivity, which ultimately challenge the downstream recovery and purification steps. In this context, electro-fermentation (EF) represents an innovative approach, based on the use of a polarized electrode interface to trigger changes in the rate, yield, titer or product distribution deriving from traditional fermentation processes. In principle, the electrode in EF can act as an electron acceptor (i.e., anodic electro-fermentation, AEF) or donor (i.e., cathodic electro-fermentation, CEF), or simply as a mean to control the oxidation-reduction potential of the fermentation broth. However, the molecular and biochemical basis underlying the EF process are still largely unknown. This review paper provides a comprehensive overview of recent literature studies including both AEF and CEF examples with either pure or mixed microbial cultures. A critical analysis of biochemical, microbiological, and engineering aspects which presently hamper the transition of the EF technology from the laboratory to the market is also presented.
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Affiliation(s)
- Bernardino Virdis
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, Brisbane, QLD 4072, Australia
| | - Robert Hoelzle
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Angela Marchetti
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Santiago T Boto
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), 07745 Jena, Germany; Faculty of Biological Sciences, Friedrich Schiller University (FSU), 07743 Jena, Germany
| | - Miriam A Rosenbaum
- Bio Pilot Plant, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute (HKI), 07745 Jena, Germany; Faculty of Biological Sciences, Friedrich Schiller University (FSU), 07743 Jena, Germany
| | - Ramiro Blasco-Gómez
- LEQUIA, Institute of the Environment, University of Girona, Maria Aurèlia Capmany 69, 17003 Girona, Spain
| | - Sebastià Puig
- LEQUIA, Institute of the Environment, University of Girona, Maria Aurèlia Capmany 69, 17003 Girona, Spain
| | - Stefano Freguia
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Marianna Villano
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
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Wang Q, Sha C, Wang H, Ma K, Wiegle J, Abomohra AEF, Shao W. A novel bifunctional aldehyde/alcohol dehydrogenase catalyzing reduction of acetyl-CoA to ethanol at temperatures up to 95 °C. Sci Rep 2021; 11:1050. [PMID: 33441766 PMCID: PMC7806712 DOI: 10.1038/s41598-020-80159-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 12/16/2020] [Indexed: 11/09/2022] Open
Abstract
Hyperthermophilic Thermotoga spp. are excellent candidates for the biosynthesis of cellulosic ethanol producing strains because they can grow optimally at 80 °C with ability to degrade and utilize cellulosic biomass. In T. neapolitana (Tne), a putative iron-containing alcohol dehydrogenase was, for the first time, revealed to be a bifunctional aldehyde/alcohol dehydrogenase (Fe-AAdh) that catalyzed both reactions from acetyl-coenzyme A (ac-CoA) to acetaldehyde (ac-ald), and from ac-ald to ethanol, while the putative aldehyde dehydrogenase (Aldh) exhibited only CoA-independent activity that oxidizes ac-ald to acetic acid. The biochemical properties of Fe-AAdh were characterized, and bioinformatics were analyzed. Fe-AAdh exhibited the highest activities for the reductions of ac-CoA and acetaldehyde at 80-85 °C, pH 7.54, and had a 1-h half-life at about 92 °C. The Fe-AAdh gene is highly conserved in Thermotoga spp., Pyrococcus furiosus and Thermococcus kodakarensis, indicating the existence of a fermentation pathway from ac-CoA to ethanol via acetaldehyde as the intermediate in hyperthermophiles.
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Affiliation(s)
- Qiang Wang
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Chong Sha
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Hongcheng Wang
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Kesen Ma
- Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Juergen Wiegle
- Department of Microbiology, University of Georgia, Athens, GA, 30602, USA
| | - Abd El-Fatah Abomohra
- Department of Environmental Engineering, School of Architecture and Civil Engineering, Chengdu University, Chengdu, 610106, China. .,Botany Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt.
| | - Weilan Shao
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China.
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Genome Editing of the Anaerobic Thermophile Thermoanaerobacter ethanolicus Using Thermostable Cas9. Appl Environ Microbiol 2020; 87:AEM.01773-20. [PMID: 33067194 DOI: 10.1128/aem.01773-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/04/2020] [Indexed: 12/11/2022] Open
Abstract
Thermoanaerobacter ethanolicus can produce acetate, lactate, hydrogen, and ethanol from sugars resulting from plant carbohydrate polymer degradation at temperatures above 65°C. T. ethanolicus is a promising candidate for thermophilic ethanol fermentations due to the utilization of both pentose and hexose. Although an ethanol balance model in T. ethanolicus has been developed, only a few physiological or biochemical experiments regarding the function of important enzymes in ethanol formation have been carried out. To address this issue, we developed a thermostable Cas9-based system for genome editing of T. ethanolicus As a proof of principle, three genes, including the thymidine kinase gene (tdk), acetaldehyde-alcohol dehydrogenase gene (adhE), and redox sensing protein gene (rsp), were chosen as editing targets, and these genes were edited successfully. As a genetic tool, we tested the gene knockout and a small DNA fragment knock-in. After optimization of the transformation strategies, 77% genome-editing efficiency was observed. Furthermore, our in vivo results revealed that redox sensing protein (RSP) plays a more important role in regulation of energy metabolism, including hydrogen production and ethanol formation. The genetic system provides us with an effective strategy to identify genes involved in biosynthesis and energy metabolism.IMPORTANCE Interest in thermophilic microorganisms as emerging metabolic engineering platforms to produce biofuels and chemicals has surged. Thermophilic microbes for biofuels have attracted great attention, due to their tolerance of high temperature and wide range of substrate utilization. On the basis of the biochemical experiments of previous investigation, the formation of ethanol was controlled via transcriptional regulation and influenced by the relevant properties of specific enzymes in T. ethanolicus Thus, there is an urgent need to understand the physiological function of these key enzymes, which requires genetic manipulations such as deletion or overexpression of genes encoding putative key enzymes. Here, we developed a thermostable Cas9-based engineering tool for gene editing in T. ethanolicus The thermostable Cas9-based genome-editing tool may further be applied to metabolically engineer T. ethanolicus to produce biofuels. This genetic system represents an important expansion of the genetic tool box of anaerobic thermophile T. ethanolicus strains.
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6
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Qu C, Chen L, Li Y, Fu H, Wang J. The redox-sensing transcriptional repressor Rex is important for regulating the products distribution in Thermoanaerobacterium aotearoense SCUT27. Appl Microbiol Biotechnol 2020; 104:5605-5617. [DOI: 10.1007/s00253-020-10554-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 02/28/2020] [Accepted: 03/16/2020] [Indexed: 01/06/2023]
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AcrR and Rex Control Mannitol and Sorbitol Utilization through Their Cross-Regulation of Aldehyde-Alcohol Dehydrogenase (AdhE) in Lactobacillus plantarum. Appl Environ Microbiol 2019; 85:AEM.02035-18. [PMID: 30530710 DOI: 10.1128/aem.02035-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/28/2018] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus plantarum is a versatile bacterium that occupies a wide range of environmental niches. In this study, we found that a bifunctional aldehyde-alcohol dehydrogenase-encoding gene, adhE, was responsible for L. plantarum being able to utilize mannitol and sorbitol through cross-regulation by two DNA-binding regulators. In L. plantarum NF92, adhE was greatly induced, and the growth of an adhE-disrupted (ΔadhE) strain was repressed when sorbitol or mannitol instead of glucose was used as a carbon source. The results of enzyme activity and metabolite assays demonstrated that AdhE could catalyze the synthesis of ethanol in L. plantarum NF92 when sorbitol or mannitol was used as the carbon source. AcrR and Rex were two transcriptional factors screened by an affinity isolation method and verified to regulate the expression of adhE DNase I footprinting assay results showed that they shared a binding site (GTTCATTAATGAAC) in the adhE promoter. Overexpression and knockout of AcrR showed that AcrR was a novel regulator to promote the transcription of adhE The activator AcrR and repressor Rex may cross-regulate adhE when L. plantarum NF92 utilizes sorbitol or mannitol. Thus, a model of the control of adhE by AcrR and Rex during L. plantarum NF92 utilization of mannitol or sorbitol was proposed.IMPORTANCE The function and regulation of AdhE in the important probiotic genus Lactobacillus are rarely reported. Here we demonstrated that AdhE is responsible for sorbitol and mannitol utilization and is cross-regulated by two transcriptional regulators in L. plantarum NF92, which had not been reported previously. This is important for L. plantarum to compete and survive in some harsh environments in which sorbitol or mannitol could be used as carbon source. A novel transcriptional regulator AcrR was identified to be important to promote the expression of adhE, which was unknown before. The cross-regulation of adhE by AcrR and Rex is important to balance the level of NADH in the cell during sorbitol or mannitol utilization.
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8
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Sander K, Chung D, Hyatt D, Westpheling J, Klingeman DM, Rodriguez M, Engle NL, Tschaplinski TJ, Davison BH, Brown SD. Rex in Caldicellulosiruptor bescii: Novel regulon members and its effect on the production of ethanol and overflow metabolites. Microbiologyopen 2019; 8:e00639. [PMID: 29797457 PMCID: PMC6391272 DOI: 10.1002/mbo3.639] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/03/2018] [Accepted: 03/05/2018] [Indexed: 11/23/2022] Open
Abstract
Rex is a global redox-sensing transcription factor that senses and responds to the intracellular [NADH]/[NAD+ ] ratio to regulate genes for central metabolism, and a variety of metabolic processes in Gram-positive bacteria. We decipher and validate four new members of the Rex regulon in Caldicellulosiruptor bescii; a gene encoding a class V aminotransferase, the HydG FeFe Hydrogenase maturation protein, an oxidoreductase, and a gene encoding a hypothetical protein. Structural genes for the NiFe and FeFe hydrogenases, pyruvate:ferredoxin oxidoreductase, as well as the rex gene itself are also members of this regulon, as has been predicted previously in different organisms. A C. bescii rex deletion strain constructed in an ethanol-producing strain made 54% more ethanol (0.16 mmol/L) than its genetic parent after 36 hr of fermentation, though only under nitrogen limited conditions. Metabolomic interrogation shows this rex-deficient ethanol-producing strain synthesizes other reduced overflow metabolism products likely in response to more reduced intracellular redox conditions and the accumulation of pyruvate. These results suggest ethanol production is strongly dependent on the native intracellular redox state in C. bescii, and highlight the combined promise of using this gene and manipulation of culture conditions to yield strains capable of producing ethanol at higher yields and final titer.
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Affiliation(s)
- Kyle Sander
- Department of Chemical and Biomolecular EngineeringUniversity of TennesseeKnoxvilleTennessee
- Bredesen Center for Interdisciplinary Graduate Research and EducationUniversity of TennesseeKnoxvilleTennessee
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
| | - Daehwan Chung
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
- Department of GeneticsUniversity of GeorgiaAthensGeorgia
- Present address:
National Renewable Energy LaboratoryGoldenCO
| | - Doug Hyatt
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
| | - Janet Westpheling
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
- Department of GeneticsUniversity of GeorgiaAthensGeorgia
| | - Dawn M. Klingeman
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
| | - Miguel Rodriguez
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
| | - Nancy L. Engle
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
| | - Timothy J. Tschaplinski
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
| | - Brian H. Davison
- Department of Chemical and Biomolecular EngineeringUniversity of TennesseeKnoxvilleTennessee
- Bredesen Center for Interdisciplinary Graduate Research and EducationUniversity of TennesseeKnoxvilleTennessee
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
| | - Steven D. Brown
- Bredesen Center for Interdisciplinary Graduate Research and EducationUniversity of TennesseeKnoxvilleTennessee
- BioEnergy Sciences CenterOak Ridge National LaboratoryOak RidgeTennessee
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
- Present address:
LanzaTechSkokieIL
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Feng K, Li H, Zheng C. Shifting product spectrum by pH adjustment during long-term continuous anaerobic fermentation of food waste. BIORESOURCE TECHNOLOGY 2018; 270:180-188. [PMID: 30218934 DOI: 10.1016/j.biortech.2018.09.035] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Revised: 09/04/2018] [Accepted: 09/06/2018] [Indexed: 06/19/2023]
Abstract
Anaerobic fermentation is widely used to recover different products from food waste, and in this study, the evolution of fermentation products and microbial community along with pH variation was investigated thoroughly using four long-term reactors. Lactic fermentation dominated the system at pH 3.2-4.5 with lactic acid concentration of 5.7-13.5 g/L, and Lactobacillus was the superior sort. Bifidobacteria increased significantly at pH 4.5, resulting in the increase of acetic acid. Butyric acid fermentation was observed at pH 4.7-5.0. Bifidobacterium, Lactobacillus, and Olsenella were still dominant, but the lactic acid produced by them was converted to volatile fatty acids (VFAs) rapidly by Megasphaera, Caproiciproducens, Solobacteria, etc. Mixed acid fermentation occurred at pH 6.0 with the highest concentration 14.2 g/L of VFAs, and the dominant Prevotella and Megasphaera converted substrates to VFAs directly. On the whole, pH 4.5 and 4.7 led to the highest hydrolysis rate of 50% and acidification rate of 45%.
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Affiliation(s)
- Kai Feng
- Shenzhen Engineering Research Laboratory for Sludge and Food Waste Treatment and Resource Recovery, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Huan Li
- Shenzhen Engineering Research Laboratory for Sludge and Food Waste Treatment and Resource Recovery, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; Guangdong Engineering Research Center of Urban Water Cycle and Environment Safety, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
| | - Chengzhi Zheng
- Technical Department of Rocktek, Rocktek Limited Liability Company, Wuhan 430223, China
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Kim JE, Jang IS, Sung BH, Kim SC, Lee JY. Rerouting of NADPH synthetic pathways for increased protopanaxadiol production in Saccharomyces cerevisiae. Sci Rep 2018; 8:15820. [PMID: 30361526 PMCID: PMC6202386 DOI: 10.1038/s41598-018-34210-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 10/11/2018] [Indexed: 11/17/2022] Open
Abstract
Ginseng (Panax ginseng) and its bioactive components, ginsenosides, are popular medicinal herbal products, exhibiting various pharmacological effects. Despite their advocated use for medication, the long cultivation periods of ginseng roots and their low ginsenoside content prevent mass production of this compound. Yeast Saccharomyces cerevisiae was engineered for production of protopanaxadiol (PPD), a type of aglycone characterizing ginsenoside. PPD-producing yeast cell factory was further engineered by obtaining a balance between enzyme expressions and altering cofactor availability. Different combinations of promoters (PGPD, PCCW12, and PADH2) were utilized to construct the PPD biosynthetic pathway. Rerouting the redox metabolism to improve NADPH availability in the engineered S. cerevisiae also increased PPD production. Combining these approaches resulted in more than an 11-fold increase in PPD titer over the initially constructed strain. The series of metabolic engineering strategies of this study provides a feasible approach for the microbial production of PPD and development of microbial platforms producing other industrially-relevant terpenoids.
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Affiliation(s)
- Jae-Eung Kim
- Center for Bio-based Chemistry, Korea Research Institute of Chemical Technology (KRICT), 406-30, Jongga-ro, Jung-gu, Ulsan, 44429, Republic of Korea
| | - In-Seung Jang
- Center for Bio-based Chemistry, Korea Research Institute of Chemical Technology (KRICT), 406-30, Jongga-ro, Jung-gu, Ulsan, 44429, Republic of Korea
| | - Bong Hyun Sung
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Sun Chang Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
| | - Ju Young Lee
- Center for Bio-based Chemistry, Korea Research Institute of Chemical Technology (KRICT), 406-30, Jongga-ro, Jung-gu, Ulsan, 44429, Republic of Korea.
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Zhu H, Wang Y, Ni Y, Zhou J, Han L, Yu Z, Mao A, Wang D, Fan H, He K. The Redox-Sensing Regulator Rex Contributes to the Virulence and Oxidative Stress Response of Streptococcus suis Serotype 2. Front Cell Infect Microbiol 2018; 8:317. [PMID: 30280091 PMCID: PMC6154617 DOI: 10.3389/fcimb.2018.00317] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 08/20/2018] [Indexed: 01/06/2023] Open
Abstract
Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen responsible for septicemia and meningitis. The redox-sensing regulator Rex has been reported to play critical roles in the metabolism regulation, oxidative stress response, and virulence of various pathogens. In this study, we identified and characterized a Rex ortholog in the SS2 virulent strain SS2-1 that is involved in bacterial pathogenicity and stress environment susceptibility. Our data show that the Rex-knockout mutant strain Δrex exhibited impaired growth in medium with hydrogen peroxide or a low pH compared with the wildtype strain SS2-1 and the complementary strain CΔrex. In addition, Δrex showed a decreased level of survival in whole blood and in RAW264.7 macrophages. Further analyses revealed that Rex deficiency significantly attenuated bacterial virulence in an animal model. A comparative proteome analysis found that the expression levels of several proteins involved in virulence and oxidative stress were significantly different in Δrex compared with SS2-1. Electrophoretic mobility shift assays revealed that recombinant Rex specifically bound to the promoters of target genes in a manner that was modulated by NADH and NAD+. Taken together, our data suggest that Rex plays critical roles in the virulence and oxidative stress response of SS2.
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Affiliation(s)
- Haodan Zhu
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China
| | - Yong Wang
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yanxiu Ni
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China
| | - Junming Zhou
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China.,Key Lab of Food Quality and Safety of Jiangsu Province, State Key Laboratory Breeding Base, Nanjing, China
| | - Lixiao Han
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Zhengyu Yu
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China
| | - Aihua Mao
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China
| | - Dandan Wang
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China
| | - Hongjie Fan
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China.,College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Kongwang He
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China.,Key Lab of Food Quality and Safety of Jiangsu Province, State Key Laboratory Breeding Base, Nanjing, China
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Characterization of the Clostridium thermocellum AdhE, NfnAB, ferredoxin and Pfor proteins for their ability to support high titer ethanol production in Thermoanaerobacterium saccharolyticum. Metab Eng 2018; 51:32-42. [PMID: 30218716 DOI: 10.1016/j.ymben.2018.09.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 08/21/2018] [Accepted: 09/11/2018] [Indexed: 12/17/2022]
Abstract
The thermophilic anaerobes Thermoanaerobacterium saccharolyticum and Clostridium thermocellum are good candidates for lignocellulosic ethanol production. T. saccharolyticum has been successfully engineered to produce ethanol at high titer (70 g/L). The maximum ethanol titer of engineered strains of C. thermocellum is only 25 g/L. We hypothesize that one or more of the enzymes in the ethanol production pathway in C. thermocellum is not adequate for ethanol production at high titer. In this study, we focused on the enzymes responsible for the part of the ethanol production pathway from pyruvate to ethanol. In T. saccharolyticum, we replaced all of the genes encoding proteins in this pathway with their homologs from C. thermocellum and examined what combination of gene replacements restricted ethanol titer. We found that a pathway consisting of Ct_nfnAB, Ct_fd, Ct_adhE and Ts_pforA was sufficient to support ethanol titer greater than 50 g/L, however replacement of Ts_pforA by Ct_pfor1 dramatically decreased the maximum ethanol titer to 14 g/L. We then demonstrated that the reason for reduced ethanol production is that the Ct_pfor1 is inhibited by accumulation of ethanol and NADH, while Ts_pforA is not.
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Hitschler L, Kuntz M, Langschied F, Basen M. Thermoanaerobacter species differ in their potential to reduce organic acids to their corresponding alcohols. Appl Microbiol Biotechnol 2018; 102:8465-8476. [DOI: 10.1007/s00253-018-9210-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/14/2018] [Accepted: 06/28/2018] [Indexed: 11/28/2022]
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The redox-sensing protein Rex modulates ethanol production in Thermoanaerobacterium saccharolyticum. PLoS One 2018; 13:e0195143. [PMID: 29621294 PMCID: PMC5886521 DOI: 10.1371/journal.pone.0195143] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 03/16/2018] [Indexed: 11/19/2022] Open
Abstract
Thermoanaerobacterium saccharolyticum is a thermophilic anaerobe that has been engineered to produce high amounts of ethanol, reaching ~90% theoretical yield at a titer of 70 g/L. Here we report the physiological changes that occur upon deleting the redox-sensing transcriptional regulator Rex in wild type T. saccharolyticum: a single deletion of rex resulted in a two-fold increase in ethanol yield (from 40% to 91% theoretical yield), but the resulting strains grew only about a third as fast as the wild type strain. Deletion of the rex gene also had the effect of increasing expression of alcohol dehydrogenase genes, adhE and adhA. After several serial transfers, the ethanol yield decreased from an average of 91% to 55%, and the growth rates had increased. We performed whole-genome resequencing to identify secondary mutations in the Δrex strains adapted for faster growth. In several cases, secondary mutations had appeared in the adhE gene. Furthermore, in these strains the NADH-linked alcohol dehydrogenase activity was greatly reduced. Complementation studies were done to reintroduce rex into the Δrex strains: reintroducing rex decreased ethanol yield to below wild type levels in the Δrex strain without adhE mutations, but did not change the ethanol yield in the Δrex strain where an adhE mutation occurred.
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Eminoğlu A, Murphy SJL, Maloney M, Lanahan A, Giannone RJ, Hettich RL, Tripathi SA, Beldüz AO, Lynd LR, Olson DG. Deletion of the hfsB gene increases ethanol production in Thermoanaerobacterium saccharolyticum and several other thermophilic anaerobic bacteria. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:282. [PMID: 29213322 PMCID: PMC5707799 DOI: 10.1186/s13068-017-0968-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 11/13/2017] [Indexed: 05/22/2023]
Abstract
BACKGROUND With the discovery of interspecies hydrogen transfer in the late 1960s (Bryant et al. in Arch Microbiol 59:20-31, 1967), it was shown that reducing the partial pressure of hydrogen could cause mixed acid fermenting organisms to produce acetate at the expense of ethanol. Hydrogen and ethanol are both more reduced than glucose. Thus there is a tradeoff between production of these compounds imposed by electron balancing requirements; however, the mechanism is not fully known. RESULTS Deletion of the hfsA or B subunits resulted in a roughly 1.8-fold increase in ethanol yield. The increase in ethanol production appears to be associated with an increase in alcohol dehydrogenase activity, which appears to be due, at least in part, to increased expression of the adhE gene, and may suggest a regulatory linkage between hfsB and adhE. We studied this system most intensively in the organism Thermoanaerobacterium saccharolyticum; however, deletion of hfsB also increases ethanol production in other thermophilic bacteria suggesting that this could be used as a general technique for engineering thermophilic bacteria for improved ethanol production in organisms with hfs-type hydrogenases. CONCLUSION Since its discovery by Shaw et al. (JAMA 191:6457-64, 2009), the hfs hydrogenase has been suspected to act as a regulator due to the presence of a PAS domain. We provide additional support for the presence of a regulatory phenomenon. In addition, we find a practical application for this scientific insight, namely increasing ethanol yield in strains that are of interest for ethanol production from cellulose or hemicellulose. In two of these organisms (T. xylanolyticum and T. thermosaccharolyticum), the ethanol yields are the highest reported to date.
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Affiliation(s)
- Ayşenur Eminoğlu
- Department of Biology, Molecular Biology Research Laboratories, Faculty of Art and Science, Recep Tayyip Erdogan University, Rize, Turkey
| | - Sean Jean-Loup Murphy
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Marybeth Maloney
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Anthony Lanahan
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Richard J. Giannone
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Robert L. Hettich
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | | | - Ali Osman Beldüz
- Department of Biology, Faculty of Science, Karadeniz Technical University, Trabzon, Turkey
| | - Lee R. Lynd
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
- Department of Biological Sciences, Dartmouth College, Hanover, NH USA
| | - Daniel G. Olson
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN USA
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16
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Hu L, Huang H, Yuan H, Tao F, Xie H, Wang S. Rex in Clostridium kluyveri is a global redox-sensing transcriptional regulator. J Biotechnol 2016; 233:17-25. [PMID: 27373958 DOI: 10.1016/j.jbiotec.2016.06.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/26/2016] [Accepted: 06/28/2016] [Indexed: 11/15/2022]
Abstract
Clostridium kluyveri is unique in fermenting ethanol and acetate to butyrate, caproate, and H2. The genes encoding butyrate-producing enzymes, including electron-bifurcating butyryl-CoA dehydrogenase/electron transfer flavoprotein complex and NADH-dependent reduced ferredoxin:NADP(+) oxidoreductase, form a cluster, which is preceded by a gene annotated as the transcriptional regulator Rex. Northern blotting and RT-PCR experiments indicated that the gene cluster forms a large transcriptional unit that possibly includes several small transcriptional units. The deduced Rex protein contains a winged helix DNA-binding domain and a Rossmann fold potentially interacting with NAD(H). Bioinformatics analysis revealed that Rex can bind the promoter regions of numerous genes, which are involved in carbon and energy metabolism, including NADH oxidation, hydrogen production, ATP synthesis, butyrate formation, and succinate metabolism. Rex may regulate the transcription of genes encoding certain transcriptional regulators and transporters. Electrophoretic mobility shift and isothermal titration calorimetry assays revealed that Rex specifically formed protein-DNA complexes with the promoter regions of target genes, which could be inhibited by NADH but restored by an excess amount of NAD(+). These results suggest that Rex plays a key role in the carbon and energy metabolism of C. kluyveri as a global transcriptional regulator in response to the cellular NADH/NAD(+) ratio.
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Affiliation(s)
- Liejie Hu
- State Key Laboratory of Microbial Technology, School of life science, Shandong University, Jinan, People's Republic of China
| | - Haiyan Huang
- State Key Laboratory of Microbial Technology, School of life science, Shandong University, Jinan, People's Republic of China; Institute of Basic Medicine, Shandong Academy of Medical Science, Jinan, People's Republic of China
| | - Hengxin Yuan
- State Key Laboratory of Microbial Technology, School of life science, Shandong University, Jinan, People's Republic of China
| | - Fei Tao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Huijun Xie
- Environment Research Institute, Shandong University, Jinan, People's Republic of China
| | - Shuning Wang
- State Key Laboratory of Microbial Technology, School of life science, Shandong University, Jinan, People's Republic of China.
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17
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Johnson EE, Rehmann L. The role of 1,3-propanediol production in fermentation of glycerol by Clostridium pasteurianum. BIORESOURCE TECHNOLOGY 2016; 209:1-7. [PMID: 26946434 DOI: 10.1016/j.biortech.2016.02.088] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/18/2016] [Accepted: 02/20/2016] [Indexed: 06/05/2023]
Abstract
Waste crude glycerol from biodiesel production can be used to produce biobutanol using Clostridium pasteurianum with the main products being n-butanol, 1,3-propanediol (PDO) and ethanol. There has been much discrepancy and mystery around the cause and effect of process parameters on the product distribution, thus a better understanding of the pathway regulation is required. This study shows that as process pH decreased, the rate of cell growth and CO2 production also decreased, resulting in slower fermentations, increased duration of butanol production and higher butanol concentrations and yields. The production rate of PDO was multi-modal and the role of PDO appears to function in redox homeostasis. The results also showed that C. pasteurianum displayed little biphasic behavior when compared to Clostridia spp. typically used in ABE fermentation due to the alternative glycolysis-independent reductive pathway of PDO production, rendering it suitable for a continuous fermentation process.
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Affiliation(s)
- Erin E Johnson
- Department of Chemical & Biochemical Engineering, The University of Western Ontario, 1151 Richmond St., London, Ontario N6A 3K7, Canada
| | - Lars Rehmann
- Department of Chemical & Biochemical Engineering, The University of Western Ontario, 1151 Richmond St., London, Ontario N6A 3K7, Canada; Department of Biochemical Engineering, AVT - Aachener Verfahrenstechnik, RWTH Aachen University, Worringer Weg 1, 52074 Aachen, Germany.
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18
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Lee JY, Kang CD, Lee SH, Park YK, Cho KM. Engineering cellular redox balance inSaccharomyces cerevisiaefor improved production of L-lactic acid. Biotechnol Bioeng 2015; 112:751-8. [DOI: 10.1002/bit.25488] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 08/28/2014] [Accepted: 10/21/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Ju Young Lee
- Biomaterials Laboratory; Samsung Advanced Institute of Technology; Gyeonggi-do Korea
| | - Chang Duk Kang
- Biomaterials Laboratory; Samsung Advanced Institute of Technology; Gyeonggi-do Korea
| | - Seung Hyun Lee
- Biomaterials Laboratory; Samsung Advanced Institute of Technology; Gyeonggi-do Korea
| | - Young Kyoung Park
- Biomaterials Laboratory; Samsung Advanced Institute of Technology; Gyeonggi-do Korea
| | - Kwang Myung Cho
- Biomaterials Laboratory; Samsung Advanced Institute of Technology; Gyeonggi-do Korea
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19
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Zheng Y, Ko TP, Yang Y, Shao W, Guo RT. Binding mode of the oxidized α-anomer of NAD+ to RSP, a Rex-family repressor. Biochem Biophys Res Commun 2014; 456:733-6. [PMID: 25527330 DOI: 10.1016/j.bbrc.2014.12.049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/09/2014] [Indexed: 11/30/2022]
Abstract
The Rex-family repressors sense redox levels by alternative binding to NADH or NAD(+). RSP is the homologue of Rex in Thermoanaerobacter ethanolicus JW200(T) and regulates ethanol fermentation in this obligate anaerobe. The dimeric repressor binds to DNA by an open conformation. The crystal structure of RSP/α-NAD(+) complex shows a different set of ligand interactions mainly due to the unique configuration of the nicotinamide moiety. The positively charged ring is covered by the Tyr102 side chain and interacts with a sulfate ion adjacent to the N-terminus of helix α8. Consequently, the RSP dimer may be locked in a closed conformation that does not bind to DNA. However, α-NAD(+) does not show a higher affinity to RSP than β-NAD(+). It has to be improved for possible use as an effector in modulating the repressor.
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Affiliation(s)
- Yingying Zheng
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Tzu-Ping Ko
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Yunyun Yang
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China; Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Weilan Shao
- Biofuels Institute, School of Environment, Jiangsu University, Zhenjiang 212013, China.
| | - Rey-Ting Guo
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China.
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20
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Zheng Y, Ko TP, Sun H, Huang CH, Pei J, Qiu R, Wang AHJ, Wiegel J, Shao W, Guo RT. Distinct structural features of Rex-family repressors to sense redox levels in anaerobes and aerobes. J Struct Biol 2014; 188:195-204. [PMID: 25463021 DOI: 10.1016/j.jsb.2014.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 11/03/2014] [Accepted: 11/06/2014] [Indexed: 02/06/2023]
Abstract
The Rex-family repressors sense redox levels by alternative binding to NADH or NAD(+). Unlike other Rex proteins that regulate aerobic respiration, RSP controls ethanol fermentation in the obligate anaerobe Thermoanaerobacter ethanolicus JW200(T). It is also found in other anaerobic microorganisms. Here we present the crystal structures of apo-RSP, RSP/NADH and RSP/NAD(+)/DNA, which are the first structures of Rex-family members from an obligate anaerobe. RSP functions as a homodimer. It assumes an open conformation when bound to the operator DNA and a closed conformation when not DNA-bound. The DNA binds to the N-terminal winged-helix domain and the dinucleotide, either reduced or oxidized, binds to the C-terminal Rossmann-fold domain. The two distinct orientations of nicotinamide ring, anti in NADH and syn in NAD(+), give rise to two sets of protein-ligand interactions. Consequently, NADH binding makes RSP into a closed conformation, which does not bind to DNA. Both the conserved residues and the DNA specificity of RSP show a number of variations from those of the aerobic Rex, reflecting different structural bases for redox-sensing by the anaerobic and aerobic Rex-family members.
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Affiliation(s)
- Yingying Zheng
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Tzu-Ping Ko
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Hong Sun
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Chun-Hsiang Huang
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Jianjun Pei
- Biofuels Institute, School of Environment, Jiangsu University, Zhenjiang 212013, China
| | - Riyong Qiu
- Biofuels Institute, School of Environment, Jiangsu University, Zhenjiang 212013, China
| | - Andrew H-J Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Juergen Wiegel
- Department of Microbiology, University of Georgia, Athens, GA 30602-2605, USA
| | - Weilan Shao
- Biofuels Institute, School of Environment, Jiangsu University, Zhenjiang 212013, China.
| | - Rey-Ting Guo
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China.
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21
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Hoelzle RD, Virdis B, Batstone DJ. Regulation mechanisms in mixed and pure culture microbial fermentation. Biotechnol Bioeng 2014; 111:2139-54. [DOI: 10.1002/bit.25321] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 05/19/2014] [Accepted: 06/25/2014] [Indexed: 11/08/2022]
Affiliation(s)
- Robert D. Hoelzle
- Advanced Water Management Centre; The University of Queensland; Brisbane QLD 4072 Australia
| | - Bernardino Virdis
- Advanced Water Management Centre; The University of Queensland; Brisbane QLD 4072 Australia
- Centre for Microbial Electrosynthesis; The University of Queensland; Brisbane QLD 4072 Australia
| | - Damien J. Batstone
- Advanced Water Management Centre; The University of Queensland; Brisbane QLD 4072 Australia
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22
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Panitz J, Zverlov V, Pham V, Stürzl S, Schieder D, Schwarz W. Isolation of a solventogenic Clostridium sp. strain: Fermentation of glycerol to n-butanol, analysis of the bcs operon region and its potential regulatory elements. Syst Appl Microbiol 2014; 37:1-9. [DOI: 10.1016/j.syapm.2013.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 10/21/2013] [Accepted: 10/28/2013] [Indexed: 12/12/2022]
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23
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Role of transcription and enzyme activities in redistribution of carbon and electron flux in response to N2 and H2 sparging of open-batch cultures of Clostridium thermocellum ATCC 27405. Appl Microbiol Biotechnol 2014; 98:2829-40. [DOI: 10.1007/s00253-013-5500-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 12/18/2013] [Accepted: 12/24/2013] [Indexed: 12/17/2022]
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Thermoanaerobacter thermohydrosulfuricus WC1 shows protein complement stability during fermentation of key lignocellulose-derived substrates. Appl Environ Microbiol 2013; 80:1602-15. [PMID: 24362431 DOI: 10.1128/aem.03555-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thermoanaerobacter spp. have long been considered suitable Clostridium thermocellum coculture partners for improving lignocellulosic biofuel production through consolidated bioprocessing. However, studies using "omic"-based profiling to better understand carbon utilization and biofuel producing pathways have been limited to only a few strains thus far. To better characterize carbon and electron flux pathways in the recently isolated, xylanolytic strain, Thermoanaerobacter thermohydrosulfuricus WC1, label-free quantitative proteomic analyses were combined with metabolic profiling. SWATH-MS proteomic analysis quantified 832 proteins in each of six proteomes isolated from mid-exponential-phase cells grown on xylose, cellobiose, or a mixture of both. Despite encoding genes consistent with a carbon catabolite repression network observed in other Gram-positive organisms, simultaneous consumption of both substrates was observed. Lactate was the major end product of fermentation under all conditions despite the high expression of gene products involved with ethanol and/or acetate synthesis, suggesting that carbon flux in this strain may be controlled via metabolite-based (allosteric) regulation or is constrained by metabolic bottlenecks. Cross-species "omic" comparative analyses confirmed similar expression patterns for end-product-forming gene products across diverse Thermoanaerobacter spp. It also identified differences in cofactor metabolism, which potentially contribute to differences in end-product distribution patterns between the strains analyzed. The analyses presented here improve our understanding of T. thermohydrosulfuricus WC1 metabolism and identify important physiological limitations to be addressed in its development as a biotechnologically relevant strain in ethanologenic designer cocultures through consolidated bioprocessing.
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Genome-wide analysis of redox reactions reveals metabolic engineering targets for D-lactate overproduction in Escherichia coli. Metab Eng 2013; 18:44-52. [PMID: 23563322 DOI: 10.1016/j.ymben.2013.03.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 02/11/2013] [Accepted: 03/12/2013] [Indexed: 11/21/2022]
Abstract
Most current metabolic engineering applications rely on the inactivation of unwanted reactions and the amplification of product-oriented reactions. All of the biochemical reactions involved with cellular metabolism are tightly coordinated with the electron flow, which depends on the cellular energy status. Thus, the cellular metabolic flux can be controlled either by modulation of the electron flow or the regulation of redox reactions. This study analyzed the genome-wide anaerobic fermentation products of 472 Escherichia coli single gene knockouts, which comprised mainly of dehydrogenases, oxidoreductases, and redox-related proteins. Many metabolic pathways that were located far from anaerobic mixed-acid fermentation significantly affected the profiles of lactic acid, succinic acid, acetic acid, formic acid, and ethanol. Unexpectedly, D-lactate overproduction was determined by a single gene deletion in dehydrogenases (e.g., guaB, pyrD, and serA) involved with nucleotide and amino acid metabolism. Furthermore, the combined knockouts of guaB, pyrD, serA, fnr, arcA, or arcB genes, which are involved with anaerobic transcription regulation, enhanced D-lactate overproduction. These results suggest that the anaerobic fermentation profiles of E. coli can be tuned via the disruption of peripheral dehydrogenases in anaerobic conditions.
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Verbeke TJ, Zhang X, Henrissat B, Spicer V, Rydzak T, Krokhin OV, Fristensky B, Levin DB, Sparling R. Genomic evaluation of Thermoanaerobacter spp. for the construction of designer co-cultures to improve lignocellulosic biofuel production. PLoS One 2013; 8:e59362. [PMID: 23555660 PMCID: PMC3608648 DOI: 10.1371/journal.pone.0059362] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 02/13/2013] [Indexed: 02/07/2023] Open
Abstract
The microbial production of ethanol from lignocellulosic biomass is a multi-component process that involves biomass hydrolysis, carbohydrate transport and utilization, and finally, the production of ethanol. Strains of the genus Thermoanaerobacter have been studied for decades due to their innate abilities to produce comparatively high ethanol yields from hemicellulose constituent sugars. However, their inability to hydrolyze cellulose, limits their usefulness in lignocellulosic biofuel production. As such, co-culturing Thermoanaerobacter spp. with cellulolytic organisms is a plausible approach to improving lignocellulose conversion efficiencies and yields of biofuels. To evaluate native lignocellulosic ethanol production capacities relative to competing fermentative end-products, comparative genomic analysis of 11 sequenced Thermoanaerobacter strains, including a de novo genome, Thermoanaerobacter thermohydrosulfuricus WC1, was conducted. Analysis was specifically focused on the genomic potential for each strain to address all aspects of ethanol production mentioned through a consolidated bioprocessing approach. Whole genome functional annotation analysis identified three distinct clades within the genus. The genomes of Clade 1 strains encode the fewest extracellular carbohydrate active enzymes and also show the least diversity in terms of lignocellulose relevant carbohydrate utilization pathways. However, these same strains reportedly are capable of directing a higher proportion of their total carbon flux towards ethanol, rather than non-biofuel end-products, than other Thermoanaerobacter strains. Strains in Clade 2 show the greatest diversity in terms of lignocellulose hydrolysis and utilization, but proportionately produce more non-ethanol end-products than Clade 1 strains. Strains in Clade 3, in which T. thermohydrosulfuricus WC1 is included, show mid-range potential for lignocellulose hydrolysis and utilization, but also exhibit extensive divergence from both Clade 1 and Clade 2 strains in terms of cellular energetics. The potential implications regarding strain selection and suitability for industrial ethanol production through a consolidated bioprocessing co-culturing approach are examined throughout the manuscript.
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Affiliation(s)
- Tobin J. Verbeke
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Xiangli Zhang
- Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Bernard Henrissat
- Centre national de la recherche scientifique, Aix-Marseille Université, Marseille, France
| | - Vic Spicer
- Department of Physics & Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Thomas Rydzak
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Oleg V. Krokhin
- Department of Internal Medicine & Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Brian Fristensky
- Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - David B. Levin
- Biosystems Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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Teth137, a Conserved Factor of Unknown Function from Thermoanaerobacter ethanolicus JW200, Represses the Transcription of the adhE Gene In Vitro. Indian J Microbiol 2012; 53:149-54. [PMID: 24426101 DOI: 10.1007/s12088-012-0339-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 11/29/2012] [Indexed: 10/27/2022] Open
Abstract
Teth137, a 13.7 kD protein of unknown function from Thermoanaerobacter ethanolicus JW200, is encoded by 360 nucleotides and has been obtained by DNA-coupled column previously. However, no function study of Teth137 has been published. Homologous modeling of Teth137 shows the protein is comprised of a helix-turn-helix motif which is a typical DNA-binding domain. Therefore, it is speculated Teth137 is a DNA-binding protein and involved in transcription of the adhE gene (encodes alcohol dehydrogenase E). To investigate the function of Teth137, recombinant Teth137 is overexpressed in Escherichia coli JM109 and purified by DEAE column. Purified Teth137 exhibits the affinity with the adhE promoter region in gel electrophoresis mobility shift assay (GEMSA). Teth137 at the concentration of 48 μM retards the migration of 5 nM of probe in the presence of the competitor DNA. Mutant analysis indicates that S69, T70, P71 and T72 are critical to protein-DNA interface; Gly substitutions at these residues results in the loss of the binding ability with the adhE promoter region. Moreover, T. ethanolicus JW200 RNA polymerase, σ subunit and template plasmid are prepared for in vitro transcription assay to detect the regulation function of Teth137. The results of the in vitro transcription show that the transcription of 5 nM of the template plasmid is inhibited by 48 μM of Teth137.
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Liu CG, Xue C, Lin YH, Bai FW. Redox potential control and applications in microaerobic and anaerobic fermentations. Biotechnol Adv 2012. [PMID: 23178703 DOI: 10.1016/j.biotechadv.2012.11.005] [Citation(s) in RCA: 144] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Many fermentation products are produced under microaerobic or anaerobic conditions, in which oxygen is undetectable by dissolved oxygen probe, presenting a challenge for process monitoring and control. Extracellular redox potentials that can be detected conveniently affect intracellular redox homeostasis and metabolism, and consequently control profiles of fermentation products, which provide an alternative for monitoring and control of these fermentation processes. This article reviews updated progress in the impact of redox potentials on gene expression, protein biosynthesis and metabolism as well as redox potential control strategies for more efficient production of fermentation products, taking ethanol fermentation by the yeast Saccharomyces under microaerobic conditions and butanol production by the bacterium Clostridium under anaerobic conditions as examples.
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Affiliation(s)
- Chen-Guang Liu
- School of Life Sciences and Biotechnology, Dalian University of Technology, Dalian 116023, China
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Joe Shaw A, Covalla SF, Miller BB, Firliet BT, Hogsett DA, Herring CD. Urease expression in a Thermoanaerobacterium saccharolyticum ethanologen allows high titer ethanol production. Metab Eng 2012; 14:528-32. [DOI: 10.1016/j.ymben.2012.06.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Revised: 06/25/2012] [Accepted: 06/27/2012] [Indexed: 11/30/2022]
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The redox-sensing protein Rex, a transcriptional regulator of solventogenesis in Clostridium acetobutylicum. Appl Microbiol Biotechnol 2012; 96:749-61. [PMID: 22576944 DOI: 10.1007/s00253-012-4112-2] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 04/13/2012] [Accepted: 04/15/2012] [Indexed: 10/28/2022]
Abstract
Solventogenic clostridia are characterised by their biphasic fermentative metabolism, and the main final product n-butanol is of particular industrial interest because it can be used as a superior biofuel. During exponential growth, Clostridium acetobutylicum synthesises acetic and butyric acids which are accompanied by the formation of molecular hydrogen and carbon dioxide. During the stationary phase, the solvents acetone, butanol and ethanol are produced. However, the molecular mechanisms of this metabolic switch are largely unknown so far. In this study, in silico, in vitro and in vivo analyses were performed to elucidate the function of the CAC2713-encoded redox-sensing transcriptional repressor Rex and its role in the solventogenic shift of C. acetobutylicum ATCC 824. Electrophoretic mobility shift assays showed that Rex controls the expression of butanol biosynthetic genes as a response to the cellular NADH/NAD(+) ratio. Interestingly, the Rex-negative mutant C. acetobutylicum rex::int(95) produced high amounts of ethanol and butanol, while hydrogen and acetone production were significantly reduced. Both ethanol and butanol (but not acetone) formation started clearly earlier than in the wild type. In addition, the rex mutant showed a de-repression of the bifunctional aldehyde/alcohol dehydrogenase 2 encoded by the adhE2 gene (CAP0035) as demonstrated by increased adhE2 expression as well as high NADH-dependent alcohol dehydrogenase activities. The results presented here clearly indicated that Rex is involved in the redox-dependent solventogenic shift of C. acetobutylicum.
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Intensification of β-poly(L: -malic acid) production by Aureobasidium pullulans ipe-1 in the late exponential growth phase. J Ind Microbiol Biotechnol 2012; 39:1073-80. [PMID: 22395899 DOI: 10.1007/s10295-012-1111-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Accepted: 02/15/2012] [Indexed: 10/28/2022]
Abstract
β-Poly(malic acid) (PMLA) has attracted industrial interest because this polyester can be used as a prodrug or for drug delivery systems. In PMLA production by Aureobasidium pullulans ipe-1, it was found that PLMA production was associated with cell growth in the early exponential growth phase and dissociated from cell growth in the late exponential growth phase. To enhance PMLA production in the late phase, different fermentation modes and strategies for controlling culture redox potential (CRP) were studied. The results showed that high concentrations of produced PMLA (above 40 g/l) not only inhibited PMLA production, but also was detrimental to cell growth. Moreover, when CRP increased from 57 to 100 mV in the late exponential growth phase, the lack of reducing power in the broth also decreased PMLA productivity. PMLA productivity could be enhanced by repeated-batch culture to maintain cell growth in the exponential growth phase, or by cell-recycle culture with membrane to remove the produced PMLA, or by maintaining CRP below 70 mV no matter which kind of fermentation mode was adopted. Repeated-batch culture afforded a high PMLA concentration (up to 63.2 g/l) with a productivity of 1.15 g l(-1) h(-1). Cell-recycle culture also confirmed that PMLA production by the strain ipe-1 was associated with cell growth.
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Revel S, Doudet L, Alonso L, Coleman AW, Shahgaldian P. Surface acoustic wave sensing of linear alcohols using para-acylcalix[n]arenes. Chem Commun (Camb) 2012; 48:73-5. [DOI: 10.1039/c1cc15352h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Transcriptional regulation of central carbon and energy metabolism in bacteria by redox-responsive repressor Rex. J Bacteriol 2011; 194:1145-57. [PMID: 22210771 DOI: 10.1128/jb.06412-11] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Redox-sensing repressor Rex was previously implicated in the control of anaerobic respiration in response to the cellular NADH/NAD(+) levels in gram-positive bacteria. We utilized the comparative genomics approach to infer candidate Rex-binding DNA motifs and assess the Rex regulon content in 119 genomes from 11 taxonomic groups. Both DNA-binding and NAD-sensing domains are broadly conserved in Rex orthologs identified in the phyla Firmicutes, Thermotogales, Actinobacteria, Chloroflexi, Deinococcus-Thermus, and Proteobacteria. The identified DNA-binding motifs showed significant conservation in these species, with the only exception detected in Clostridia, where the Rex motif deviates in two positions from the generalized consensus, TTGTGAANNNNTTCACAA. Comparative analysis of candidate Rex sites revealed remarkable variations in functional repertoires of candidate Rex-regulated genes in various microorganisms. Most of the reconstructed regulatory interactions are lineage specific, suggesting frequent events of gain and loss of regulator binding sites in the evolution of Rex regulons. We identified more than 50 novel Rex-regulated operons encoding functions that are essential for resumption of the NADH:NAD(+) balance. The novel functional role of Rex in the control of the central carbon metabolism and hydrogen production genes was validated by in vitro DNA binding assays using the TM0169 protein in the hydrogen-producing bacterium Thermotoga maritima.
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Mutant selection and phenotypic and genetic characterization of ethanol-tolerant strains of Clostridium thermocellum. Appl Microbiol Biotechnol 2011; 92:641-52. [PMID: 21874277 DOI: 10.1007/s00253-011-3492-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 07/06/2011] [Accepted: 07/15/2011] [Indexed: 10/17/2022]
Abstract
Clostridium thermocellum is a model microorganism for converting cellulosic biomass into fuels and chemicals via consolidated bioprocessing. One of the challenges for industrial application of this organism is its low ethanol tolerance, typically 1-2% (w/v) in wild-type strains. In this study, we report the development and characterization of mutant C. thermocellum strains that can grow in the presence of high ethanol concentrations. Starting from a single colony, wild-type C. thermocellum ATCC 27405 was sub-cultured and adapted for growth in up to 50 g/L ethanol using either cellobiose or crystalline cellulose as the growth substrate. Both the adapted strains retained their ability to grow on either substrate and displayed a higher growth rate and biomass yield than the wild-type strain in the absence of ethanol. With added ethanol in the media, the mutant strains displayed an inverse correlation between ethanol concentration and growth rate or biomass yield. Genome sequencing revealed six common mutations in the two ethanol-tolerant strains including an alcohol dehydrogenase gene and genes involved in arginine/pyrimidine biosynthetic pathway. The potential role of these mutations in ethanol tolerance phenotype is discussed.
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Rydzak T, Levin DB, Cicek N, Sparling R. End-product induced metabolic shifts in Clostridium thermocellum ATCC 27405. Appl Microbiol Biotechnol 2011; 92:199-209. [DOI: 10.1007/s00253-011-3511-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 07/15/2011] [Accepted: 07/22/2011] [Indexed: 12/01/2022]
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