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Jiang Y, Guo D, Lu J, Dürre P, Dong W, Yan W, Zhang W, Ma J, Jiang M, Xin F. Consolidated bioprocessing of butanol production from xylan by a thermophilic and butanologenic Thermoanaerobacterium sp. M5. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:89. [PMID: 29619085 PMCID: PMC5879998 DOI: 10.1186/s13068-018-1092-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 03/21/2018] [Indexed: 05/24/2023]
Abstract
BACKGROUND Consolidated bioprocessing (CBP) has attracted increasing attention since it can accomplish hydrolytic enzymes production, lignocellulose degradation and microbial fermentation in one single step. Currently, biobutanol is mainly produced by mesophilic and solventogenic clostridia, such as Clostridium beijerinckii and C. acetobutylicum, which cannot directly utilize lignocellulose, an abundant, renewable and economic feedstock. Hence, metabolic construction or isolation of novel cellulolytic/hemicellulolytic and solventogenic bacteria to achieve direct butanol production from lignocellulose offers a promising alternative. RESULTS In this study, a newly isolated Thermoanaerobacterium sp. M5 could directly produce butanol from xylan through CBP at 55 °C via the butanol-ethanol pathway. Further genomic and proteomic analysis showed that the capabilities of efficient xylan degradation and butanol synthesis were attributed to the efficient expression of xylanase, β-xylosidase and the bifunctional alcohol/aldehyde dehydrogenase (AdhE). Process optimization based on the characteristic of AdhE could further improve the final butanol titer to 1.17 g/L from xylan through CBP. Furthermore, a new co-cultivation system consisting of Thermoanaerobacterium sp. M5 which could release xylose from xylan efficiently and C. acetobutylicum NJ4 which possesses the capacity of high butanol production was established. This microbial co-cultivation system could improve the butanol titer to 8.34 g/L, representing the highest butanol titer from xylan through CBP. CONCLUSIONS A newly thermophilic and butanogenic bacterium Thermoanaerobacterium sp. M5 was isolated and key enzymes responsible for butanol production were characterized in this study. High butanol titer was obtained from xylan through process optimization. In addition, the newly set up microbial co-cultivation system, consisting of Thermoanaerobacterium sp. M5 and C. acetobutylicum NJ4, achieved the highest butanol production from xylan compared with the reported co-cultivation systems.
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Affiliation(s)
- Yujia Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800 People’s Republic of China
| | - Dong Guo
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800 People’s Republic of China
| | - Jiasheng Lu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800 People’s Republic of China
| | - Peter Dürre
- Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
| | - Weiliang Dong
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800 People’s Republic of China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800 People’s Republic of China
| | - Wei Yan
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800 People’s Republic of China
| | - Wenming Zhang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800 People’s Republic of China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800 People’s Republic of China
| | - Jiangfeng Ma
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800 People’s Republic of China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800 People’s Republic of China
| | - Min Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800 People’s Republic of China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800 People’s Republic of China
| | - Fengxue Xin
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, Nanjing, 211800 People’s Republic of China
- Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800 People’s Republic of China
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Engineering the conserved and noncatalytic residues of a thermostable β-1,4-endoglucanase to improve specific activity and thermostability. Sci Rep 2018; 8:2954. [PMID: 29440674 PMCID: PMC5811441 DOI: 10.1038/s41598-018-21246-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 02/01/2018] [Indexed: 12/18/2022] Open
Abstract
Endoglucanases are increasingly applied in agricultural and industrial applications as a key biocatalyst for cellulose biodegradation. However, the low performance in extreme conditions seriously challenges the enzyme’s commercial utilization. To obtain endoglucanases with substantially improved activity and thermostability, structure-based rational design was carried out based on the Chaetomium thermophilum β-1,4-endoglucanase CTendo45. In this study, five mutant enzymes were constructed by substitution of conserved and noncatalytic residues using site-directed mutagenesis. Mutants were constitutively expressed in Pichia pastoris, purified, and ultimately tested for enzymatic characteristics. Two single mutants, Y30F and Y173F, increased the enzyme’s specific activity 1.35- and 1.87-fold using carboxymethylcellulose sodium (CMC-Na) as a substrate, respectively. Furthermore, CTendo45 and mutants exhibited higher activity towards β-D-glucan than that of CMC-Na, and activities of Y173F and Y30F were also increased obviously against β-D-glucan. In addition, Y173F significantly improved the enzyme’s heat resistance at 80 °C and 90 °C. More interestingly, the double mutant Y30F/Y173F obtained considerably higher stability at elevated temperatures but failed to inherit the increased catalytic efficiency of its single mutant counterparts. This work gives an initial insight into the biological function of conserved and noncatalytic residues of thermostable endoglucanases and proposes a feasible path for the improvement of enzyme redesign proposals.
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Jiang Y, Xin F, Lu J, Dong W, Zhang W, Zhang M, Wu H, Ma J, Jiang M. State of the art review of biofuels production from lignocellulose by thermophilic bacteria. BIORESOURCE TECHNOLOGY 2017. [PMID: 28634129 DOI: 10.1016/j.biortech.2017.05.142] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Biofuels, including ethanol and butanol, are mainly produced by mesophilic solventogenic yeasts and Clostridium species. However, these microorganisms cannot directly utilize lignocellulosic materials, which are abundant, renewable and non-compete with human demand. More recently, thermophilic bacteria show great potential for biofuels production, which could efficiently degrade lignocellulose through the cost effective consolidated bioprocessing. Especially, it could avoid contamination in the whole process owing to its relatively high fermentation temperature. However, wild types thermophiles generally produce low levels of biofuels, hindering their large scale production. This review comprehensively summarizes the state of the art development of biofuels production by reported thermophilic microorganisms, and also concludes strategies to improve biofuels production including the metabolic pathways construction, co-culturing systems and biofuels tolerance. In addition, strategies to further improve butanol production are proposed.
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Affiliation(s)
- Yujia Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Fengxue Xin
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Jiasheng Lu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Weiliang Dong
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Wenming Zhang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211800, PR China
| | - Min Zhang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Hao Wu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211800, PR China
| | - Jiangfeng Ma
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Min Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211800, PR China.
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Rahayu F, Kawai Y, Iwasaki Y, Yoshida K, Kita A, Tajima T, Kato J, Murakami K, Hoshino T, Nakashimada Y. Thermophilic ethanol fermentation from lignocellulose hydrolysate by genetically engineered Moorella thermoacetica. BIORESOURCE TECHNOLOGY 2017; 245:1393-1399. [PMID: 28583404 DOI: 10.1016/j.biortech.2017.05.146] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/20/2017] [Accepted: 05/22/2017] [Indexed: 06/07/2023]
Abstract
A transformant of Moorella thermoacetica was constructed for thermophilic ethanol production from lignocellulosic biomass by deleting two phosphotransacetylase genes, pdul1 and pdul2, and introducing the native aldehyde dehydrogenase gene (aldh) controlled by the promoter from glyceraldehyde-3-phosphate dehydrogenase. The transformant showed tolerance to 540mM and fermented sugars including fructose, glucose, galactose and xylose to mainly ethanol. In a mixed-sugar medium of glucose and xylose, all of the sugars were consumed to produce ethanol at the yield of 1.9mol/mol-sugar. The transformant successfully fermented sugars in hydrolysate prepared through the acid hydrolysis of lignocellulose to ethanol, suggesting that this transformant can be used to ferment the sugars in lignocellulosic biomass for ethanol production.
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Affiliation(s)
- Farida Rahayu
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; Indonesian Sweetener and Fiber Crops Research Institute, Jalan Raya Karangploso Km 9, Malang, East Java 65152, Indonesia
| | - Yuto Kawai
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Yuki Iwasaki
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Koichiro Yoshida
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Akihisa Kita
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Takahisa Tajima
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Junichi Kato
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Katsuji Murakami
- Biomass Refinery Research Center, National Institute of Advanced Industrial Science and Technology, 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan
| | - Tamotsu Hoshino
- Biomass Refinery Research Center, National Institute of Advanced Industrial Science and Technology, 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan
| | - Yutaka Nakashimada
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan.
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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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Xu T, Li Y, He Z, Van Nostrand JD, Zhou J. Cas9 Nickase-Assisted RNA Repression Enables Stable and Efficient Manipulation of Essential Metabolic Genes in Clostridium cellulolyticum. Front Microbiol 2017; 8:1744. [PMID: 28936208 PMCID: PMC5594222 DOI: 10.3389/fmicb.2017.01744] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/28/2017] [Indexed: 11/16/2022] Open
Abstract
Essential gene functions remain largely underexplored in bacteria. Clostridium cellulolyticum is a promising candidate for consolidated bioprocessing; however, its genetic manipulation to reduce the formation of less-valuable acetate is technically challenging due to the essentiality of acetate-producing genes. Here we developed a Cas9 nickase-assisted chromosome-based RNA repression to stably manipulate essential genes in C. cellulolyticum. Our plasmid-based expression of antisense RNA (asRNA) molecules targeting the phosphotransacetylase (pta) gene successfully reduced the enzymatic activity by 35% in cellobiose-grown cells, metabolically decreased the acetate titer by 15 and 52% in wildtype transformants on cellulose and xylan, respectively. To control both acetate and lactate simultaneously, we transformed the repression plasmid into lactate production-deficient mutant and found the plasmid delivery reduced acetate titer by more than 33%, concomitant with negligible lactate formation. The strains with pta gene repression generally diverted more carbon into ethanol. However, further testing on chromosomal integrants that were created by double-crossover recombination exhibited only very weak repression because DNA integration dramatically lessened gene dosage. With the design of a tandem repetitive promoter-driven asRNA module and the use of a new Cas9 nickase genome editing tool, a chromosomal integrant (LM3P) was generated in a single step and successfully enhanced RNA repression, with a 27% decrease in acetate titer on cellulose in antibiotic-free medium. These results indicate the effectiveness of tandem promoter-driven RNA repression modules in promoting gene repression in chromosomal integrants. Our combinatorial method using a Cas9 nickase genome editing tool to integrate the gene repression module demonstrates easy-to-use and high-efficiency advantages, paving the way for stably manipulating genes, even essential ones, for functional characterization and microbial engineering.
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Affiliation(s)
- Tao Xu
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, NormanOK, United States
| | - Yongchao Li
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, NormanOK, United States
| | - Zhili He
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, NormanOK, United States
| | - Joy D. Van Nostrand
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, NormanOK, United States
| | - Jizhong Zhou
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, NormanOK, United States
- Earth Sciences Division, Lawrence Berkeley National Laboratory, BerkeleyCA, United States
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua UniversityBeijing, China
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Jensen TØ, Pogrebnyakov I, Falkenberg KB, Redl S, Nielsen AT. Application of the thermostable β-galactosidase, BgaB, from Geobacillus stearothermophilus as a versatile reporter under anaerobic and aerobic conditions. AMB Express 2017; 7:169. [PMID: 28875485 PMCID: PMC5585113 DOI: 10.1186/s13568-017-0469-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 08/29/2017] [Indexed: 11/10/2022] Open
Abstract
Use of thermophilic organisms has a range of advantages, but the significant lack of engineering tools limits their applications. Here we show that β-galactosidase from Geobacillus stearothermophilus (BgaB) can be applicable in a range of conditions, including different temperatures and oxygen concentrations. This protein functions both as a marker, promoting colony color development in the presence of a lactose analogue S-gal, and as a reporter enabling quantitative measurement by a simple colorimetric assay. Optimal performance was observed at 70 °C and pH 6.4. The gene was introduced into G. thermoglucosidans. The combination of BgaB expressed from promoters of varying strength with S-gal produced distinct black colonies in aerobic and anaerobic conditions at temperatures ranging from 37 to 60 °C. It showed an important advantage over the conventional β-galactosidase (LacZ) and substrate X-gal, which were inactive at high temperature and under anaerobic conditions. To demonstrate the versatility of the reporter, a promoter library was constructed by randomizing sequences around −35 and −10 regions in a wild type groES promoter from Geobacillus sp. GHH01. The library contained 28 promoter variants and encompassed fivefold variation. The experimental pipeline allowed construction and measurement of expression levels of the library in just 4 days. This β-galactosidase provides a promising tool for engineering of aerobic, anaerobic, and thermophilic production organisms such as Geobacillus species.
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Zhu M, Fan W, Cha Y, Yang X, Lai Z, Li S, Wang X. Dynamic cell responses in Thermoanaerobacterium sp. under hyperosmotic stress. Sci Rep 2017; 7:10088. [PMID: 28855699 PMCID: PMC5577258 DOI: 10.1038/s41598-017-10514-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 08/09/2017] [Indexed: 12/17/2022] Open
Abstract
As a nongenetic engineering technique, adaptive evolution is an effective and easy-to-operate approach to strain improvement. In this work, a commercial Thermoanaerobacterium aotearoense SCUT27/Δldh-G58 was successfully isolated via sequential batch fermentation with step-increased carbon concentrations. Mutants were isolated under selective high osmotic pressures for 58 passages. The evolved isolate rapidly catabolized sugars at high concentrations and subsequently produced ethanol with good yield. A 1.6-fold improvement of ethanol production was achieved in a medium containing 120 g/L of carbon substrate using the evolved strain, compared to the start strain. The analysis of transcriptome and intracellular solute pools suggested that the adaptive evolution altered the synthesis of some compatible solutes and activated the DNA repair system in the two Thermoanaerobacterium sp. evolved strains. Overall, the results indicated the potential of adaptive evolution as a simple and effective tool for the modification and optimization of industrial microorganisms.
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Affiliation(s)
- Muzi Zhu
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Wudi Fan
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Yaping Cha
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Xiaofeng Yang
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Zhicheng Lai
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Shuang Li
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China.
| | - Xiaoning Wang
- State Key Laboratory of Kidney, the Institute of Life Sciences, Chinese PLA General Hospital, Beijing, China
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Hon S, Olson DG, Holwerda EK, Lanahan AA, Murphy SJL, Maloney MI, Zheng T, Papanek B, Guss AM, Lynd LR. The ethanol pathway from Thermoanaerobacterium saccharolyticum improves ethanol production in Clostridium thermocellum. Metab Eng 2017; 42:175-184. [PMID: 28663138 DOI: 10.1016/j.ymben.2017.06.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 05/27/2017] [Accepted: 06/23/2017] [Indexed: 12/31/2022]
Abstract
Clostridium thermocellum ferments cellulose, is a promising candidate for ethanol production from cellulosic biomass, and has been the focus of studies aimed at improving ethanol yield. Thermoanaerobacterium saccharolyticum ferments hemicellulose, but not cellulose, and has been engineered to produce ethanol at high yield and titer. Recent research has led to the identification of four genes in T. saccharolyticum involved in ethanol production: adhE, nfnA, nfnB and adhA. We introduced these genes into C. thermocellum and observed significant improvements to ethanol yield, titer, and productivity. The four genes alone, however, were insufficient to achieve in C. thermocellum the ethanol yields and titers observed in engineered T. saccharolyticum strains, even when combined with gene deletions targeting hydrogen production. This suggests that other parts of T. saccharolyticum metabolism may also be necessary to reproduce the high ethanol yield and titer phenotype in C. thermocellum.
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Affiliation(s)
- Shuen Hon
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Daniel G Olson
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA.
| | - Evert K Holwerda
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Anthony A Lanahan
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Sean J L Murphy
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Marybeth I Maloney
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Tianyong Zheng
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Beth Papanek
- Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Adam M Guss
- Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Lee R Lynd
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA.
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Honda K, Kimura K, Ninh PH, Taniguchi H, Okano K, Ohtake H. In vitro bioconversion of chitin to pyruvate with thermophilic enzymes. J Biosci Bioeng 2017; 124:296-301. [PMID: 28527827 DOI: 10.1016/j.jbiosc.2017.04.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 04/19/2017] [Indexed: 01/16/2023]
Abstract
Chitin is the second most abundant organic compound on the planet and thus has been regarded as an alternative resource to petroleum feedstocks. One of the key challenges in the biological conversion of biomass-derived polysaccharides, such as cellulose and chitin, is to close the gap between optimum temperatures for enzymatic saccharification and microbial fermentation and to implement them in a single bioreactor. To address this issue, in the present study, we aimed to perform an in vitro, one-pot bioconversion of chitin to pyruvate, which is a precursor of a wide range of useful metabolites. Twelve thermophilic enzymes, including that for NAD+ regeneration, were heterologously produced in Escherichia coli and semi-purified by heat treatment of the crude extract of recombinant cells. When the experimentally decided concentrations of enzymes were incubated with 0.5 mg mL-1 colloidal chitin (equivalent to 2.5 mM N-acetylglucosamine unit) and an adequate set of cofactors at 70°C, 0.62 mM pyruvate was produced in 5 h. Despite the use of a cofactor-balanced pathway, determination of the pool sizes of cofactors showed a rapid decrease in ATP concentration, most probably due to the thermally stable ATP-degrading enzyme(s) derived from the host cell. Integration of an additional enzyme set of thermophilic adenylate kinase and polyphosphate kinase led to the deceleration of ATP degradation, and the final product titer was improved to 2.1 mM.
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Affiliation(s)
- Kohsuke Honda
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Keisuke Kimura
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Pham Huynh Ninh
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hironori Taniguchi
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Kenji Okano
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hisao Ohtake
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Both adhE and a Separate NADPH-Dependent Alcohol Dehydrogenase Gene, adhA, Are Necessary for High Ethanol Production in Thermoanaerobacterium saccharolyticum. J Bacteriol 2017; 199:JB.00542-16. [PMID: 27849176 DOI: 10.1128/jb.00542-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 11/10/2016] [Indexed: 01/01/2023] Open
Abstract
Thermoanaerobacterium saccharolyticum has been engineered to produce ethanol at about 90% of the theoretical maximum yield (2 ethanol molecules per glucose equivalent) and a titer of 70 g/liter. Its ethanol-producing ability has drawn attention to its metabolic pathways, which could potentially be transferred to other organisms of interest. Here, we report that the iron-containing AdhA is important for ethanol production in the high-ethanol strain of T. saccharolyticum (LL1049). A single-gene deletion of adhA in LL1049 reduced ethanol production by ∼50%, whereas multiple gene deletions of all annotated alcohol dehydrogenase genes except adhA and adhE did not affect ethanol production. Deletion of adhA in wild-type T.saccharolyticum reduced NADPH-linked alcohol dehydrogenase (ADH) activity (acetaldehyde-reducing direction) by 93%.IMPORTANCE In this study, we set out to identify the alcohol dehydrogenases necessary for high ethanol production in T. saccharolyticum Based on previous work, we had assumed that adhE was the primary alcohol dehydrogenase gene. Here, we show that both adhA and adhE are needed for high ethanol yield in the engineered strain LL1049. This is the first report showing adhA is important for ethanol production in a native adhA host, which has important implications for achieving higher ethanol yields in other microorganisms.
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Zhou J, Shao X, Olson DG, Murphy SJL, Tian L, Lynd LR. Determining the roles of the three alcohol dehydrogenases (AdhA, AdhB and AdhE) in Thermoanaerobacter ethanolicus during ethanol formation. J Ind Microbiol Biotechnol 2017; 44:745-757. [PMID: 28078513 DOI: 10.1007/s10295-016-1896-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 12/22/2016] [Indexed: 12/25/2022]
Abstract
Thermoanaerobacter ethanolicus is a promising candidate for biofuel production due to the broad range of substrates it can utilize and its high ethanol yield compared to other thermophilic bacteria, such as Clostridium thermocellum. Three alcohol dehydrogenases, AdhA, AdhB and AdhE, play key roles in ethanol formation. To study their physiological roles during ethanol formation, we deleted them separately and in combination. Previously, it has been thought that both AdhB and AdhE were bifunctional alcohol dehydrogenases. Here we show that AdhE has primarily acetyl-CoA reduction activity (ALDH) and almost no acetaldehyde reduction (ADH) activity, whereas AdhB has no ALDH activity and but high ADH activity. We found that AdhA and AdhB have similar patterns of activity. Interestingly, although deletion of both adhA and adhB reduced ethanol production, a single deletion of either one actually increased ethanol yields by 60-70%.
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Affiliation(s)
- Jilai Zhou
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Xiongjun Shao
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Daniel G Olson
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Sean Jean-Loup Murphy
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Liang Tian
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.,Bioenergy Science Center, Oak Ridge, TN, USA
| | - Lee R Lynd
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA. .,Bioenergy Science Center, Oak Ridge, TN, USA.
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63
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Ábrego U, Chen Z, Wan C. Consolidated Bioprocessing Systems for Cellulosic Biofuel Production. ADVANCES IN BIOENERGY 2017. [DOI: 10.1016/bs.aibe.2017.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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64
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Moreno AD, Alvira P, Ibarra D, Tomás-Pejó E. Production of Ethanol from Lignocellulosic Biomass. PRODUCTION OF PLATFORM CHEMICALS FROM SUSTAINABLE RESOURCES 2017. [DOI: 10.1007/978-981-10-4172-3_12] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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65
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Hon S, Lanahan AA, Tian L, Giannone RJ, Hettich RL, Olson DG, Lynd LR. Development of a plasmid-based expression system in Clostridium thermocellum and its use to screen heterologous expression of bifunctional alcohol dehydrogenases ( adhEs). Metab Eng Commun 2016; 3:120-129. [PMID: 29142822 PMCID: PMC5678826 DOI: 10.1016/j.meteno.2016.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 03/15/2016] [Accepted: 04/21/2016] [Indexed: 12/27/2022] Open
Abstract
Clostridium thermocellum is a promising candidate for ethanol production from cellulosic biomass, but requires metabolic engineering to improve ethanol yield. A key gene in the ethanol production pathway is the bifunctional aldehyde and alcohol dehydrogenase, adhE. To explore the effects of overexpressing wild-type, mutant, and exogenous adhEs, we developed a new expression plasmid, pDGO144, that exhibited improved transformation efficiency and better gene expression than its predecessor, pDGO-66. This new expression plasmid will allow for many other metabolic engineering and basic research efforts in C. thermocellum. As proof of concept, we used this plasmid to express 12 different adhE genes (both wild type and mutant) from several organisms. Ethanol production varied between clones immediately after transformation, but tended to converge to a single value after several rounds of serial transfer. The previously described mutant C. thermocellum D494G adhE gave the best ethanol production, which is consistent with previously published results.
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Affiliation(s)
- Shuen Hon
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- BioEnergy Science Center, Oak Ridge, TN, USA
| | - Anthony A. Lanahan
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- BioEnergy Science Center, Oak Ridge, TN, USA
| | - Liang Tian
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- BioEnergy Science Center, Oak Ridge, TN, USA
| | - Richard J. Giannone
- BioEnergy Science Center, Oak Ridge, TN, USA
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Robert L. Hettich
- BioEnergy Science Center, Oak Ridge, TN, USA
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Daniel G. Olson
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- BioEnergy Science Center, Oak Ridge, TN, USA
| | - Lee R. Lynd
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- BioEnergy Science Center, Oak Ridge, TN, USA
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66
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Advances in Consolidated Bioprocessing Using Clostridium thermocellumand Thermoanaerobacter saccharolyticum. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1002/9783527807796.ch10] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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67
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Rhee MS, Sawhney N, Kim YS, Rhee HJ, Hurlbert JC, St John FJ, Nong G, Rice JD, Preston JF. GH115 α-glucuronidase and GH11 xylanase from Paenibacillus sp. JDR-2: potential roles in processing glucuronoxylans. Appl Microbiol Biotechnol 2016; 101:1465-1476. [PMID: 27766358 DOI: 10.1007/s00253-016-7899-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 09/13/2016] [Accepted: 09/25/2016] [Indexed: 01/26/2023]
Abstract
Paenibacillus sp. JDR-2 (Pjdr2) has been studied as a model for development of bacterial biocatalysts for efficient processing of xylans, methylglucuronoxylan, and methylglucuronoarabinoxylan, the predominant hemicellulosic polysaccharides found in dicots and monocots, respectively. Pjdr2 produces a cell-associated GH10 endoxylanase (Xyn10A1) that catalyzes depolymerization of xylans to xylobiose, xylotriose, and methylglucuronoxylotriose with methylglucuronate-linked α-1,2 to the nonreducing terminal xylose. A GH10/GH67 xylan utilization regulon includes genes encoding an extracellular cell-associated Xyn10A1 endoxylanase and an intracellular GH67 α-glucuronidase active on methylglucuronoxylotriose generated by Xyn10A1 but without activity on methylglucuronoxylotetraose generated by a GH11 endoxylanase. The sequenced genome of Pjdr2 contains three paralogous genes potentially encoding GH115 α-glucuronidases found in certain bacteria and fungi. One of these, Pjdr2_5977, shows enhanced expression during growth on xylans along with Pjdr2_4664 encoding a GH11 endoxylanase. Here, we show that Pjdr2_5977 encodes a GH115 α-glucuronidase, Agu115A, with maximal activity on the aldouronate methylglucuronoxylotetraose selectively generated by a GH11 endoxylanase Xyn11 encoded by Pjdr2_4664. Growth of Pjdr2 on this methylglucuronoxylotetraose supports a process for Xyn11-mediated extracellular depolymerization of methylglucuronoxylan and Agu115A-mediated intracellular deglycosylation as an alternative to the GH10/GH67 system previously defined in this bacterium. A recombinantly expressed enzyme encoded by the Pjdr2 agu115A gene catalyzes removal of 4-O-methylglucuronate residues α-1,2 linked to internal xylose residues in oligoxylosides generated by GH11 and GH30 xylanases and releases methylglucuronate from polymeric methylglucuronoxylan. The GH115 α-glucuronidase from Pjdr2 extends the discovery of this activity to members of the phylum Firmicutes and contributes to a novel system for bioprocessing hemicelluloses.
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Affiliation(s)
- Mun Su Rhee
- Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL, 32611, USA.,Xycrobe Therapeutics Inc., 3210 Merryfield Row, San Diego,, CA, 92121,, USA
| | - Neha Sawhney
- Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL, 32611, USA.,Department of Chemistry, Vanderbilt University, Nashville, TN, 37235,, USA
| | - Young Sik Kim
- Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL, 32611, USA
| | - Hyun Jee Rhee
- Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL, 32611, USA.,Department of Materials Science and Engineering, Massachusetts Institute of Technology, 6-113, Cambridge, MA, 02139,, USA
| | - Jason C Hurlbert
- Department of Chemistry, Physics and Geology, Winthrop University, Rock Hill, SC, 29733, USA
| | - Franz J St John
- Forest Products Laboratory, United States Forest Service, The United States Department of Agriculture, Madison, Madison,, WI, 53726, USA
| | - Guang Nong
- Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL, 32611, USA
| | - John D Rice
- Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL, 32611, USA
| | - James F Preston
- Department of Microbiology and Cell Science, University of Florida, PO Box 110700, Gainesville, FL, 32611, USA.
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68
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Akbas MY, Stark BC. Recent trends in bioethanol production from food processing byproducts. J Ind Microbiol Biotechnol 2016; 43:1593-1609. [PMID: 27565674 DOI: 10.1007/s10295-016-1821-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 07/30/2016] [Indexed: 12/19/2022]
Abstract
The widespread use of corn starch and sugarcane as sources of sugar for the production of ethanol via fermentation may negatively impact the use of farmland for production of food. Thus, alternative sources of fermentable sugars, particularly from lignocellulosic sources, have been extensively investigated. Another source of fermentable sugars with substantial potential for ethanol production is the waste from the food growing and processing industry. Reviewed here is the use of waste from potato processing, molasses from processing of sugar beets into sugar, whey from cheese production, byproducts of rice and coffee bean processing, and other food processing wastes as sugar sources for fermentation to ethanol. Specific topics discussed include the organisms used for fermentation, strategies, such as co-culturing and cell immobilization, used to improve the fermentation process, and the use of genetic engineering to improve the performance of ethanol producing fermenters.
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Affiliation(s)
- Meltem Yesilcimen Akbas
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze-Kocaeli, Kocaeli, 41400, Turkey. .,Institute of Biotechnology, Gebze Technical University, Gebze-Kocaeli, Kocaeli, 41400, Turkey.
| | - Benjamin C Stark
- Biology Department, Illinois Institute of Technology, Chicago, IL, 60616, USA
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69
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Amores GR, Guazzaroni ME, Arruda LM, Silva-Rocha R. Recent Progress on Systems and Synthetic Biology Approaches to Engineer Fungi As Microbial Cell Factories. Curr Genomics 2016; 17:85-98. [PMID: 27226765 PMCID: PMC4864837 DOI: 10.2174/1389202917666151116212255] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 05/23/2015] [Accepted: 06/01/2015] [Indexed: 01/03/2023] Open
Abstract
Filamentous fungi are remarkable organisms naturally specialized in deconstructing plant
biomass and this feature has a tremendous potential for biofuel production from renewable sources.
The past decades have been marked by a remarkable progress in the genetic engineering of fungi to
generate industry-compatible strains needed for some biotech applications. In this sense, progress in
this field has been marked by the utilization of high-throughput techniques to gain deep understanding
of the molecular machinery controlling the physiology of these organisms, starting thus the Systems
Biology era of fungi. Additionally, genetic engineering has been extensively applied to modify wellcharacterized
promoters in order to construct new expression systems with enhanced performance under the conditions of
interest. In this review, we discuss some aspects related to significant progress in the understating and engineering of
fungi for biotechnological applications, with special focus on the construction of synthetic promoters and circuits in organisms
relevant for industry. Different engineering approaches are shown, and their potential and limitations for the construction
of complex synthetic circuits in these organisms are examined. Finally, we discuss the impact of engineered
promoter architecture in the single-cell behavior of the system, an often-neglected relationship with a tremendous impact
in the final performance of the process of interest. We expect to provide here some new directions to drive future research
directed to the construction of high-performance, engineered fungal strains working as microbial cell factories.
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70
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Zhou J, Wu K, Rao CV. Evolutionary engineering of Geobacillus thermoglucosidasius
for improved ethanol production. Biotechnol Bioeng 2016; 113:2156-67. [DOI: 10.1002/bit.25983] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 02/12/2016] [Accepted: 03/18/2016] [Indexed: 01/30/2023]
Affiliation(s)
- Jiewen Zhou
- Department of Chemical and Biomolecular Engineering; University of Illinois at Urbana-Champaign; 600 S. Mathews Ave Urbana Illinois 61801
| | - Kang Wu
- Department of Chemical Engineering; University of New Hampshire; Durham New Hampshire
| | - Christopher V. Rao
- Department of Chemical and Biomolecular Engineering; University of Illinois at Urbana-Champaign; 600 S. Mathews Ave Urbana Illinois 61801
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Beri D, Olson DG, Holwerda EK, Lynd LR. Nicotinamide cofactor ratios in engineered strains of Clostridium thermocellum and Thermoanaerobacterium saccharolyticum. FEMS Microbiol Lett 2016; 363:fnw091. [PMID: 27190292 DOI: 10.1093/femsle/fnw091] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2016] [Indexed: 12/30/2022] Open
Abstract
Clostridium thermocellum and Thermoanaerobacterium saccharolyticum are bacteria under investigation for production of biofuels from plant biomass. Thermoanaerobacterium saccharolyticum has been engineered to produce ethanol at high yield (>90% of theoretical) and titer (>70 g/l). Efforts to engineer C. thermocellum have not, to date, been as successful, and efforts are underway to transfer the ethanol production pathway from T. saccharolyticum to C. thermocellum One potential challenge in transferring metabolic pathways is the possibility of incompatible levels of nicotinamide cofactors. These cofactors (NAD(+), NADH, NADP(+) and NADPH) and their oxidation state are important in the context of microbial redox metabolism. In this study we directly measured the concentrations and reduced oxidized ratios of these cofactors in a number of strains of C. thermocellum and T. saccharolyticum by using acid/base extraction and enzymatic assays. We found that cofactor ratios are maintained in a fairly narrow range, regardless of the metabolic network modifications considered. We have found that the ratios are similar in both organisms, which is a relevant observation in the context of transferring the T. saccharolyticum ethanol production pathway to C. thermocellum.
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Affiliation(s)
- Dhananjay Beri
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755, USA BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, 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 37830, USA
| | - Evert K Holwerda
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755, USA BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - 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 37830, USA
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72
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Engineering nonphosphorylative metabolism to generate lignocellulose-derived products. Nat Chem Biol 2016; 12:247-53. [DOI: 10.1038/nchembio.2020] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 12/15/2015] [Indexed: 11/09/2022]
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73
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Efficient butanol-ethanol (B-E) production from carbon monoxide fermentation by Clostridium carboxidivorans. Appl Microbiol Biotechnol 2016; 100:3361-70. [PMID: 26810079 DOI: 10.1007/s00253-015-7238-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 12/04/2015] [Accepted: 12/07/2015] [Indexed: 01/13/2023]
Abstract
The fermentation of waste gases rich in carbon monoxide using acetogens is an efficient way to obtain valuable biofuels like ethanol and butanol. Different experiments were carried out with the bacterial species Clostridium carboxidivorans as biocatalyst. In batch assays with no pH regulation, after complete substrate exhaustion, acetic acid, butyric acid, and ethanol were detected while only negligible butanol production was observed. On the other side, in bioreactors, with continuous carbon monoxide supply and pH regulation, both C2 and C4 fatty acids were initially formed as well as ethanol and butanol at concentrations never reported before for this type of anaerobic bioconversion of gaseous C1 compounds, showing that the operating conditions significantly affect the metabolic fermentation profile and butanol accumulation. Maximum ethanol and butanol concentrations in the bioreactors were obtained at pH 5.75, reaching values of 5.55 and 2.66 g/L, respectively. The alcohols were produced both from CO fermentation as well as from the bioconversion of previously accumulated acetic and butyric acids, resulting in low residual concentrations of such acids at the end of the bioreactor experiments. CO consumption was often around 50% and reached up to more than 80%. Maximum specific rates of ethanol and butanol production were reached at pH 4.75, with values of 0.16 g/h*g of biomass and 0.07 g/h*g of biomass, respectively, demonstrating that a low pH was more favorable to solventogenesis in this process, although it negatively affects biomass growth which does also play a role in the final alcohol titer.
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Herring CD, Kenealy WR, Joe Shaw A, Covalla SF, Olson DG, Zhang J, Ryan Sillers W, Tsakraklides V, Bardsley JS, Rogers SR, Thorne PG, Johnson JP, Foster A, Shikhare ID, Klingeman DM, Brown SD, Davison BH, Lynd LR, Hogsett DA. Strain and bioprocess improvement of a thermophilic anaerobe for the production of ethanol from wood. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:125. [PMID: 27313661 PMCID: PMC4910263 DOI: 10.1186/s13068-016-0536-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 05/31/2016] [Indexed: 05/16/2023]
Abstract
BACKGROUND The thermophilic, anaerobic bacterium Thermoanaerobacterium saccharolyticum digests hemicellulose and utilizes the major sugars present in biomass. It was previously engineered to produce ethanol at yields equivalent to yeast. While saccharolytic anaerobes have been long studied as potential biomass-fermenting organisms, development efforts for commercial ethanol production have not been reported. RESULTS Here, we describe the highest ethanol titers achieved from T. saccharolyticum during a 4-year project to develop it for industrial production of ethanol from pre-treated hardwood at 51-55 °C. We describe organism and bioprocess development efforts undertaken to improve ethanol production. The final strain M2886 was generated by removing genes for exopolysaccharide synthesis, the regulator perR, and re-introduction of phosphotransacetylase and acetate kinase into the methyglyoxal synthase gene. It was also subject to multiple rounds of adaptation and selection, resulting in mutations later identified by resequencing. The highest ethanol titer achieved was 70 g/L in batch culture with a mixture of cellobiose and maltodextrin. In a "mock hydrolysate" Simultaneous Saccharification and Fermentation (SSF) with Sigmacell-20, glucose, xylose, and acetic acid, an ethanol titer of 61 g/L was achieved, at 92 % of theoretical yield. Fungal cellulases were rapidly inactivated under these conditions and had to be supplemented with cellulosomes from C. thermocellum. Ethanol titers of 31 g/L were reached in a 100 L SSF of pre-treated hardwood and 26 g/L in a fermentation of a hardwood hemicellulose extract. CONCLUSIONS This study demonstrates that thermophilic anaerobes are capable of producing ethanol at high yield and at titers greater than 60 g/L from purified substrates, but additional work is needed to produce the same ethanol titers from pre-treated hardwood.
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Affiliation(s)
- Christopher D. Herring
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
| | - William R. Kenealy
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Verdezyne, Carlsbad, CA USA
| | - A. Joe Shaw
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Novogy Inc, Cambridge, MA 02138 USA
| | | | - Daniel G. Olson
- />Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
- />Bioenergy Science Center, Oak Ridge, TN USA
| | - Jiayi Zhang
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Genzyme, Cambridge, MA USA
| | - W. Ryan Sillers
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Myriant Corporation, Quincy, MA USA
| | - Vasiliki Tsakraklides
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Novogy Inc, Cambridge, MA 02138 USA
| | | | | | | | - Jessica P. Johnson
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Washington, DC, USA
| | - Abigail Foster
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
| | - Indraneel D. Shikhare
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Nalco Champion, Houston, TX USA
| | - Dawn M. Klingeman
- />Bioenergy Science Center, Oak Ridge, TN USA
- />Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Steven D. Brown
- />Bioenergy Science Center, Oak Ridge, TN USA
- />Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Brian H. Davison
- />Bioenergy Science Center, Oak Ridge, TN USA
- />Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Lee R. Lynd
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
- />Bioenergy Science Center, Oak Ridge, TN USA
| | - David A. Hogsett
- />Mascoma Corporation, 67 Etna Rd, Lebanon, NH 03766 USA
- />Novozymes Inc, Davis, CA USA
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Ji SQ, Wang B, Lu M, Li FL. Direct bioconversion of brown algae into ethanol by thermophilic bacterium Defluviitalea phaphyphila. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:81. [PMID: 27042210 PMCID: PMC4818487 DOI: 10.1186/s13068-016-0494-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 03/22/2016] [Indexed: 05/13/2023]
Abstract
BACKGROUND Brown algae are promising feedstocks for biofuel production with inherent advantages of no structural lignin, high growth rate, and no competition for land and fresh water. However, it is difficult for one microorganism to convert all components of brown algae with different oxidoreduction potentials to ethanol. Defluviitalea phaphyphila Alg1 is the first characterized thermophilic bacterium capable of direct utilization of brown algae. RESULTS Defluviitalea phaphyphila Alg1 can simultaneously utilize mannitol, glucose, and alginate to produce ethanol, and high ethanol yields of 0.47 g/g-mannitol, 0.44 g/g-glucose, and 0.3 g/g-alginate were obtained. A rational redox balance system under obligate anaerobic condition in fermenting brown algae was revealed in D. phaphyphila Alg1 through genome and redox analysis. The excess reducing equivalents produced from mannitol metabolism were equilibrated by oxidizing forces from alginate assimilation. Furthermore, D. phaphyphila Alg1 can directly utilize unpretreated kelp powder, and 10 g/L of ethanol was accumulated within 72 h with an ethanol yield of 0.25 g/g-kelp. Microscopic observation further demonstrated the deconstruction process of brown algae cell by D. phaphyphila Alg1. CONCLUSIONS The integrated biomass deconstruction system of D. phaphyphila Alg1, as well as its high ethanol yield, provided us an excellent alternative for brown algae bioconversion at elevated temperature.
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Affiliation(s)
- Shi-Qi Ji
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, 266101 People’s Republic of China
| | - Bing Wang
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, 266101 People’s Republic of China
| | - Ming Lu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, 266101 People’s Republic of China
| | - Fu-Li Li
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, 266101 People’s Republic of China
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Enhanced hydrolysis of lignocellulosic biomass: Bi-functional enzyme complexes expressed inPichia pastorisimprove bioethanol production fromMiscanthus sinensis. Biotechnol J 2015; 10:1912-9. [DOI: 10.1002/biot.201500081] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 07/17/2015] [Accepted: 10/26/2015] [Indexed: 01/13/2023]
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77
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Zhu M, Lu Y, Wang J, Li S, Wang X. Carbon Catabolite Repression and the Related Genes of ccpA, ptsH and hprK in Thermoanaerobacterium aotearoense. PLoS One 2015; 10:e0142121. [PMID: 26540271 PMCID: PMC4634974 DOI: 10.1371/journal.pone.0142121] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/16/2015] [Indexed: 01/09/2023] Open
Abstract
The strictly anaerobic, Gram-positive bacterium, Thermoanaerobacterium aotearoense SCUT27, is capable of producing ethanol, hydrogen and lactic acid by directly fermenting glucan, xylan and various lignocellulosically derived sugars. By using non-metabolizable and metabolizable sugars as substrates, we found that cellobiose, galactose, arabinose and starch utilization was strongly inhibited by the existence of 2-deoxyglucose (2-DG). However, the xylose and mannose consumptions were not markedly affected by 2-DG at the concentration of one-tenth of the metabolizable sugar. Accordingly, T. aotearoense SCUT27 could consume xylose and mannose in the presence of glucose. The carbon catabolite repression (CCR) related genes, ccpA, ptsH and hprK were confirmed to exist in T. aotearoense SCUT27 through gene cloning and protein characterization. The highly purified Histidine-containing Protein (HPr) could be specifically phosphorylated at Serine 46 by HPr kinase/phosphatase (HPrK/P) with no need to add fructose-1,6-bisphosphate (FBP) or glucose-6-phosphate (Glc-6-P) in the reaction mixture. The specific protein-interaction of catabolite control protein A (CcpA) and phosphorylated HPr was proved via affinity chromatography in the absence of formaldehyde. The equilibrium binding constant (KD) of CcpA and HPrSerP was determined as 2.22 ± 0.36 nM by surface plasmon resonance (SPR) analysis, indicating the high affinity between these two proteins.
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Affiliation(s)
- Muzi Zhu
- Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Yanping Lu
- Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Jufang Wang
- Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
| | - Shuang Li
- Provincial Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, China
- * E-mail:
| | - Xiaoning Wang
- State Key Laboratory of Kidney, the Institute of Life Sciences, Chinese PLA General Hospital, Beijing, China
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78
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Current status and prospects of industrial bio-production of n-butanol in China. Biotechnol Adv 2015; 33:1493-501. [DOI: 10.1016/j.biotechadv.2014.10.007] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/17/2014] [Accepted: 10/19/2014] [Indexed: 01/04/2023]
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79
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Ghazaryan A, Blbulyan S, Poladyan A, Trchounian A. Redox stress in geobacilli from geothermal springs: Phenomenon and membrane-associated response mechanisms. Bioelectrochemistry 2015; 105:1-6. [DOI: 10.1016/j.bioelechem.2015.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 04/08/2015] [Indexed: 10/23/2022]
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80
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Deletion of nfnAB in Thermoanaerobacterium saccharolyticum and Its Effect on Metabolism. J Bacteriol 2015; 197:2920-9. [PMID: 26124241 DOI: 10.1128/jb.00347-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 06/23/2015] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED NfnAB catalyzes the reversible transfer of electrons from reduced ferredoxin and NADH to 2 NADP(+). The NfnAB complex has been hypothesized to be the main enzyme for ferredoxin oxidization in strains of Thermoanaerobacterium saccharolyticum engineered for increased ethanol production. NfnAB complex activity was detectable in crude cell extracts of T. saccharolyticum. Activity was also detected using activity staining of native PAGE gels. The nfnAB gene was deleted in different strains of T. saccharolyticum to determine its effect on end product formation. In wild-type T. saccharolyticum, deletion of nfnAB resulted in a 46% increase in H2 formation but otherwise little change in other fermentation products. In two engineered strains with 80% theoretical ethanol yield, loss of nfnAB caused two different responses: in one strain, ethanol yield decreased to about 30% of the theoretical value, while another strain had no change in ethanol yield. Biochemical analysis of cell extracts showed that the ΔnfnAB strain with decreased ethanol yield had NADPH-linked alcohol dehydrogenase (ADH) activity, while the ΔnfnAB strain with unchanged ethanol yield had NADH-linked ADH activity. Deletion of nfnAB caused loss of NADPH-linked ferredoxin oxidoreductase activity in all cell extracts. Significant NADH-linked ferredoxin oxidoreductase activity was seen in all cell extracts, including those that had lost nfnAB. This suggests that there is an unidentified NADH:ferredoxin oxidoreductase (distinct from nfnAB) playing a role in ethanol formation. The NfnAB complex plays a key role in generating NADPH in a strain that had become reliant on NADPH-ADH activity. IMPORTANCE Thermophilic anaerobes that can convert biomass-derived sugars into ethanol have been investigated as candidates for biofuel formation. Many anaerobes have been genetically engineered to increase biofuel formation; however, key aspects of metabolism remain unknown and poorly understood. One example is the mechanism for ferredoxin oxidation and transfer of electrons to NAD(P)(+). The electron-bifurcating enzyme complex NfnAB is known to catalyze the reversible transfer of electrons from reduced ferredoxin and NADH to 2 NADP(+) and is thought to play key roles linking NAD(P)(H) metabolism with ferredoxin metabolism. We report the first deletion of nfnAB and demonstrate a role for NfnAB in metabolism and ethanol formation in Thermoanaerobacterium saccharolyticum and show that this may be an important feature among other thermophilic ethanologenic anaerobes.
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Currie DH, Raman B, Gowen CM, Tschaplinski TJ, Land ML, Brown SD, Covalla SF, Klingeman DM, Yang ZK, Engle NL, Johnson CM, Rodriguez M, Shaw AJ, Kenealy WR, Lynd LR, Fong SS, Mielenz JR, Davison BH, Hogsett DA, Herring CD. Genome-scale resources for Thermoanaerobacterium saccharolyticum. BMC SYSTEMS BIOLOGY 2015; 9:30. [PMID: 26111937 PMCID: PMC4518999 DOI: 10.1186/s12918-015-0159-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 03/09/2015] [Indexed: 01/12/2023]
Abstract
Background Thermoanaerobacterium saccharolyticum is a hemicellulose-degrading thermophilic anaerobe that was previously engineered to produce ethanol at high yield. A major project was undertaken to develop this organism into an industrial biocatalyst, but the lack of genome information and resources were recognized early on as a key limitation. Results Here we present a set of genome-scale resources to enable the systems level investigation and development of this potentially important industrial organism. Resources include a complete genome sequence for strain JW/SL-YS485, a genome-scale reconstruction of metabolism, tiled microarray data showing transcription units, mRNA expression data from 71 different growth conditions or timepoints and GC/MS-based metabolite analysis data from 42 different conditions or timepoints. Growth conditions include hemicellulose hydrolysate, the inhibitors HMF, furfural, diamide, and ethanol, as well as high levels of cellulose, xylose, cellobiose or maltodextrin. The genome consists of a 2.7 Mbp chromosome and a 110 Kbp megaplasmid. An active prophage was also detected, and the expression levels of CRISPR genes were observed to increase in association with those of the phage. Hemicellulose hydrolysate elicited a response of carbohydrate transport and catabolism genes, as well as poorly characterized genes suggesting a redox challenge. In some conditions, a time series of combined transcription and metabolite measurements were made to allow careful study of microbial physiology under process conditions. As a demonstration of the potential utility of the metabolic reconstruction, the OptKnock algorithm was used to predict a set of gene knockouts that maximize growth-coupled ethanol production. The predictions validated intuitive strain designs and matched previous experimental results. Conclusion These data will be a useful asset for efforts to develop T. saccharolyticum for efficient industrial production of biofuels. The resources presented herein may also be useful on a comparative basis for development of other lignocellulose degrading microbes, such as Clostridium thermocellum. Electronic supplementary material The online version of this article (doi:10.1186/s12918-015-0159-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Devin H Currie
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA.
| | - Babu Raman
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA. .,Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN, 46268, USA.
| | - Christopher M Gowen
- Chemical and Life Science Engineering, Virginia Commonwealth University, P.O. Box 843028, Richmond, Virginia, 23284, USA. .,Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada.
| | - Timothy J Tschaplinski
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Miriam L Land
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Steven D Brown
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Sean F Covalla
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA.
| | - Dawn M Klingeman
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Zamin K Yang
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Nancy L Engle
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Courtney M Johnson
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Miguel Rodriguez
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - A Joe Shaw
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA. .,Novogy Inc, Cambridge, MA, 02138, USA.
| | | | - Lee R Lynd
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA. .,Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.
| | - Stephen S Fong
- Chemical and Life Science Engineering, Virginia Commonwealth University, P.O. Box 843028, Richmond, Virginia, 23284, USA.
| | - Jonathan R Mielenz
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Brian H Davison
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | | | - Christopher D Herring
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA. .,Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.
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82
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Cofactor Specificity of the Bifunctional Alcohol and Aldehyde Dehydrogenase (AdhE) in Wild-Type and Mutant Clostridium thermocellum and Thermoanaerobacterium saccharolyticum. J Bacteriol 2015; 197:2610-9. [PMID: 26013492 DOI: 10.1128/jb.00232-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 05/21/2015] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED Clostridium thermocellum and Thermoanaerobacterium saccharolyticum are thermophilic bacteria that have been engineered to produce ethanol from the cellulose and hemicellulose fractions of biomass, respectively. Although engineered strains of T. saccharolyticum produce ethanol with a yield of 90% of the theoretical maximum, engineered strains of C. thermocellum produce ethanol at lower yields (∼50% of the theoretical maximum). In the course of engineering these strains, a number of mutations have been discovered in their adhE genes, which encode both alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) enzymes. To understand the effects of these mutations, the adhE genes from six strains of C. thermocellum and T. saccharolyticum were cloned and expressed in Escherichia coli, the enzymes produced were purified by affinity chromatography, and enzyme activity was measured. In wild-type strains of both organisms, NADH was the preferred cofactor for both ALDH and ADH activities. In high-ethanol-producing (ethanologen) strains of T. saccharolyticum, both ALDH and ADH activities showed increased NADPH-linked activity. Interestingly, the AdhE protein of the ethanologenic strain of C. thermocellum has acquired high NADPH-linked ADH activity while maintaining NADH-linked ALDH and ADH activities at wild-type levels. When single amino acid mutations in AdhE that caused increased NADPH-linked ADH activity were introduced into C. thermocellum and T. saccharolyticum, ethanol production increased in both organisms. Structural analysis of the wild-type and mutant AdhE proteins was performed to provide explanations for the cofactor specificity change on a molecular level. IMPORTANCE This work describes the characterization of the AdhE enzyme from different strains of C. thermocellum and T. saccharolyticum. C. thermocellum and T. saccharolyticum are thermophilic anaerobes that have been engineered to make high yields of ethanol and can solubilize components of plant biomass and ferment the sugars to ethanol. In the course of engineering these strains, several mutations arose in the bifunctional ADH/ALDH protein AdhE, changing both enzyme activity and cofactor specificity. We show that changing AdhE cofactor specificity from mostly NADH linked to mostly NADPH linked resulted in higher ethanol production by C. thermocellum and T. saccharolyticum.
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83
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Olson DG, Sparling R, Lynd LR. Ethanol production by engineered thermophiles. Curr Opin Biotechnol 2015; 33:130-41. [PMID: 25745810 DOI: 10.1016/j.copbio.2015.02.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/11/2015] [Accepted: 02/13/2015] [Indexed: 12/17/2022]
Abstract
We compare a number of different strategies that have been pursued to engineer thermophilic microorganisms for increased ethanol production. Ethanol production from pyruvate can proceed via one of four pathways, which are named by the key pyruvate dissimilating enzyme: pyruvate decarboxylase (PDC), pyruvate dehydrogenase (PDH), pyruvate formate lyase (PFL), and pyruvate ferredoxin oxidoreductase (PFOR). For each of these pathways except PFL, we see examples where ethanol production has been engineered with a yield of >90% of the theoretical maximum. In each of these cases, this engineering was achieved mainly by modulating expression of native genes. We have not found an example where a thermophilic ethanol production pathway has been transferred to a non-ethanol-producing organism to produce ethanol at high yield. A key reason for the lack of transferability of ethanol production pathways is the current lack of understanding of the enzymes involved.
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Affiliation(s)
- Daniel G Olson
- Thayer School of Engineering at Dartmouth College, Hanover, NH 03755, United States; BioEnergy Science Center, Oak Ridge, TN 37830, United States
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada R3T 5V6
| | - Lee R Lynd
- Thayer School of Engineering at Dartmouth College, Hanover, NH 03755, United States; BioEnergy Science Center, Oak Ridge, TN 37830, United States.
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84
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Moshi AP, Hosea KMM, Elisante E, Mamo G, Mattiasson B. High temperature simultaneous saccharification and fermentation of starch from inedible wild cassava (Manihot glaziovii) to bioethanol using Caloramator boliviensis. BIORESOURCE TECHNOLOGY 2015; 180:128-136. [PMID: 25594508 DOI: 10.1016/j.biortech.2014.12.087] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 12/23/2014] [Accepted: 12/24/2014] [Indexed: 06/04/2023]
Abstract
The thermoanaerobe, Caloramator boliviensis was used to ferment starch hydrolysate from inedible wild cassava to ethanol at 60°C. A raw starch degrading α-amylase was used to hydrolyse the cassava starch. During fermentation, the organism released CO2 and H2 gases, and Gas Endeavour System was successfully used for monitoring and recording formation of these gaseous products. The bioethanol produced in stoichiometric amounts to CO2 was registered online in Gas Endeavour software and correlated strongly (R(2)=0.99) with values measured by HPLC. The organism was sensitive to cyanide that exists in cassava flour. However, after acclimatisation, it was able to grow and ferment cassava starch hydrolysate containing up to 0.2ppm cyanide. The reactor hydrogen partial pressure had influence on the bioethanol production. In fed-batch fermentation by maintaining the hydrogen partial pressure around 590Pa, the organism was able to ferment up to 76g/L glucose and produced 33g/L ethanol.
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Affiliation(s)
- Anselm P Moshi
- Division of Biotechnology, Lund University, P.O. Box 124, SE-22100 Lund, Sweden; Department of Molecular Biology and Biotechnology, College of Natural and Applied Sciences, Uvumbuzi Road, Mwalimu J.K. Nyerere Mlimani Campus, University of Dar es Salaam, P.O. Box 35179, Dar es Salaam, Tanzania; Tanzania Industrial Research and Development Organization (TIRDO), Kimweri Avenue, TIRDO Complex, Msasani, P.O. Box 23235, Dar-es salaam, Tanzania.
| | - Ken M M Hosea
- Department of Molecular Biology and Biotechnology, College of Natural and Applied Sciences, Uvumbuzi Road, Mwalimu J.K. Nyerere Mlimani Campus, University of Dar es Salaam, P.O. Box 35179, Dar es Salaam, Tanzania.
| | - Emrode Elisante
- Department of Molecular Biology and Biotechnology, College of Natural and Applied Sciences, Uvumbuzi Road, Mwalimu J.K. Nyerere Mlimani Campus, University of Dar es Salaam, P.O. Box 35179, Dar es Salaam, Tanzania.
| | - G Mamo
- Division of Biotechnology, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
| | - Bo Mattiasson
- Division of Biotechnology, Lund University, P.O. Box 124, SE-22100 Lund, Sweden; also at Indienz AB, Annebergs Gård, SE-26873 Billeberga, Sweden.
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85
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The bifunctional alcohol and aldehyde dehydrogenase gene, adhE, is necessary for ethanol production in Clostridium thermocellum and Thermoanaerobacterium saccharolyticum. J Bacteriol 2015; 197:1386-93. [PMID: 25666131 DOI: 10.1128/jb.02450-14] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
UNLABELLED Thermoanaerobacterium saccharolyticum and Clostridium thermocellum are anaerobic thermophilic bacteria being investigated for their ability to produce biofuels from plant biomass. The bifunctional alcohol and aldehyde dehydrogenase gene, adhE, is present in these bacteria and has been known to be important for ethanol formation in other anaerobic alcohol producers. This study explores the inactivation of the adhE gene in C. thermocellum and T. saccharolyticum. Deletion of adhE reduced ethanol production by >95% in both T. saccharolyticum and C. thermocellum, confirming that adhE is necessary for ethanol formation in both organisms. In both adhE deletion strains, fermentation products shifted from ethanol to lactate production and resulted in lower cell density and longer time to reach maximal cell density. In T. saccharolyticum, the adhE deletion strain lost >85% of alcohol dehydrogenase (ADH) activity. Aldehyde dehydrogenase (ALDH) activity did not appear to be affected, although ALDH activity was low in cell extracts. Adding ubiquinone-0 to the ALDH assay increased activity in the T. saccharolyticum parent strain but did not increase activity in the adhE deletion strain, suggesting that ALDH activity was inhibited. In C. thermocellum, the adhE deletion strain lost >90% of ALDH and ADH activity in cell extracts. The C. thermocellum adhE deletion strain contained a point mutation in the lactate dehydrogenase gene, which appears to deregulate its activation by fructose 1,6-bisphosphate, leading to constitutive activation of lactate dehydrogenase. IMPORTANCE Thermoanaerobacterium saccharolyticum and Clostridium thermocellum are bacteria that have been investigated for their ability to produce biofuels from plant biomass. They have been engineered to produce higher yields of ethanol, yet questions remain about the enzymes responsible for ethanol formation in these bacteria. The genomes of these bacteria encode multiple predicted aldehyde and alcohol dehydrogenases which could be responsible for alcohol formation. This study explores the inactivation of adhE, a gene encoding a bifunctional alcohol and aldehyde dehydrogenase. Deletion of adhE reduced ethanol production by >95% in both T. saccharolyticum and C. thermocellum, confirming that adhE is necessary for ethanol formation in both organisms. In strains without adhE, we note changes in biochemical activity, product formation, and growth.
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86
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Vishnivetskaya TA, Hamilton-Brehm SD, Podar M, Mosher JJ, Palumbo AV, Phelps TJ, Keller M, Elkins JG. Community analysis of plant biomass-degrading microorganisms from Obsidian Pool, Yellowstone National Park. MICROBIAL ECOLOGY 2015; 69:333-345. [PMID: 25319238 DOI: 10.1007/s00248-014-0500-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 09/16/2014] [Indexed: 06/04/2023]
Abstract
The conversion of lignocellulosic biomass into biofuels can potentially be improved by employing robust microorganisms and enzymes that efficiently deconstruct plant polysaccharides at elevated temperatures. Many of the geothermal features of Yellowstone National Park (YNP) are surrounded by vegetation providing a source of allochthonic material to support heterotrophic microbial communities adapted to utilize plant biomass as a primary carbon and energy source. In this study, a well-known hot spring environment, Obsidian Pool (OBP), was examined for potential biomass-active microorganisms using cultivation-independent and enrichment techniques. Analysis of 33,684 archaeal and 43,784 bacterial quality-filtered 16S rRNA gene pyrosequences revealed that archaeal diversity in the main pool was higher than bacterial; however, in the vegetated area, overall bacterial diversity was significantly higher. Of notable interest was a flooded depression adjacent to OBP supporting a stand of Juncus tweedyi, a heat-tolerant rush commonly found growing near geothermal features in YNP. The microbial community from heated sediments surrounding the plants was enriched in members of the Firmicutes including potentially (hemi)cellulolytic bacteria from the genera Clostridium, Anaerobacter, Caloramator, Caldicellulosiruptor, and Thermoanaerobacter. Enrichment cultures containing model and real biomass substrates were established at a wide range of temperatures (55-85 °C). Microbial activity was observed up to 80 °C on all substrates including Avicel, xylan, switchgrass, and Populus sp. Independent of substrate, Caloramator was enriched at lower (<65 °C) temperatures while highly active cellulolytic bacteria Caldicellulosiruptor were dominant at high (>65 °C) temperatures.
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Affiliation(s)
- Tatiana A Vishnivetskaya
- BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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87
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Zhou J, Olson DG, Lanahan AA, Tian L, Murphy SJL, Lo J, Lynd LR. Physiological roles of pyruvate ferredoxin oxidoreductase and pyruvate formate-lyase in Thermoanaerobacterium saccharolyticum JW/SL-YS485. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:138. [PMID: 26379770 PMCID: PMC4570089 DOI: 10.1186/s13068-015-0304-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 08/03/2015] [Indexed: 05/04/2023]
Abstract
BACKGROUND Thermoanaerobacter saccharolyticum is a thermophilic microorganism that has been engineered to produce ethanol at high titer (30-70 g/L) and greater than 90 % theoretical yield. However, few genes involved in pyruvate to ethanol production pathway have been unambiguously identified. In T. saccharolyticum, the products of six putative pfor gene clusters and one pfl gene may be responsible for the conversion of pyruvate to acetyl-CoA. To gain insights into the physiological roles of PFOR and PFL, we studied the effect of deletions of several genes thought to encode these activities. RESULTS It was found that pyruvate ferredoxin oxidoreductase enzyme (PFOR) is encoded by the pforA gene and plays a key role in pyruvate dissimilation. We further demonstrated that pyruvate formate-lyase activity (PFL) is encoded by the pfl gene. Although the pfl gene is normally expressed at low levels, it is crucial for biosynthesis in T. saccharolyticum. In pforA deletion strains, pfl expression increased and was able to partially compensate for the loss of PFOR activity. Deletion of both pforA and pfl resulted in a strain that required acetate and formate for growth and produced lactate as the primary fermentation product, achieving 88 % theoretical lactate yield. CONCLUSION PFOR encoded by Tsac_0046 and PFL encoded by Tsac_0628 are only two routes for converting pyruvate to acetyl-CoA in T. saccharolyticum. The physiological role of PFOR is pyruvate dissimilation, whereas that of PFL is supplying C1 units for biosynthesis.
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Affiliation(s)
- Jilai Zhou
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Daniel G Olson
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Anthony A Lanahan
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Liang Tian
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Sean Jean-Loup Murphy
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Jonathan Lo
- />Department of Biological Sciences at Dartmouth College, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Lee R Lynd
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />Department of Biological Sciences at Dartmouth College, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
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88
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Shaw AJ, Miller BB, Rogers SR, Kenealy WR, Meola A, Bhandiwad A, Sillers WR, Shikhare I, Hogsett DA, Herring CD. Anaerobic detoxification of acetic acid in a thermophilic ethanologen. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:75. [PMID: 27279899 PMCID: PMC4898469 DOI: 10.1186/s13068-015-0257-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 04/24/2015] [Indexed: 05/22/2023]
Abstract
BACKGROUND The liberation of acetate from hemicellulose negatively impacts fermentations of cellulosic biomass, limiting the concentrations of substrate that can be effectively processed. Solvent-producing bacteria have the capacity to convert acetate to the less toxic product acetone, but to the best of our knowledge, this trait has not been transferred to an organism that produces ethanol at high yield. RESULTS We have engineered a five-step metabolic pathway to convert acetic acid to acetone in the thermophilic anaerobe Thermoanaerobacterium saccharolyticum. The first steps of the pathway, a reversible conversion of acetate to acetyl-CoA, are catalyzed by the native T. saccharolyticum enzymes acetate kinase and phosphotransacetylase. ack and pta normally divert 30% of catabolic carbon flux to acetic acid; however, their re-introduction in evolved ethanologen strains resulted in virtually no acetic acid production. Conversion between acetic acid and acetyl-CoA remained active, as evidenced by rapid (13)C label transfer from exogenous acetate to ethanol. Genomic re-sequencing of six independently evolved ethanologen strains showed convergent mutations in the hfs hydrogenase gene cluster, which when transferred to wildtype T. saccharolyticum conferred a low acid production phenotype. Thus, the mutated hfs genes effectively separate acetic acid production and consumption from central metabolism, despite their intersecting at the common intermediate acetyl-CoA. To drive acetic acid conversion to a less inhibitory product, the enzymes thiolase, acetoacetate:acetate CoA-transferase, and acetoacetate decarboxylase were assembled in T. saccharolyticum with genes from thermophilic donor organisms that do not natively produce acetone. The resultant strain converted acetic acid to acetone and ethanol while maintaining a metabolic yield of 0.50 g ethanol per gram carbohydrate. CONCLUSIONS Conversion of acetic acid to acetone results in improved ethanol productivity and titer and is an attractive low-cost solution to acetic acid inhibition.
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Affiliation(s)
- A Joe Shaw
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Novogy Inc., 85 Bolton St, Cambridge, MA 02140 USA
| | | | | | - William R Kenealy
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Verdezyne Inc., 2715 Loker Avenue West, Carlsbad, CA 92010 USA
| | - Alex Meola
- />Mascoma Corporation, Lebanon, NH 03766 USA
| | - Ashwini Bhandiwad
- />Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 USA
- />Energy Biosciences Institute, 2151 Berkeley Way, Berkeley, CA 94704 USA
| | - W Ryan Sillers
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Myriant Corporation, 66 Cummings Park, Woburn, MA 01801 USA
| | | | - David A Hogsett
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />OPX Biotechnologies Inc., 2425 55th Street, Boulder, CO 80301 USA
| | - Christopher D Herring
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 USA
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89
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Niu H, Leak D, Shah N, Kontoravdi C. Metabolic characterization and modeling of fermentation process of an engineered Geobacillus thermoglucosidasius strain for bioethanol production with gas stripping. Chem Eng Sci 2015. [DOI: 10.1016/j.ces.2014.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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90
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Shao X, DiMarco K, Richard TL, Lynd LR. Winter rye as a bioenergy feedstock: impact of crop maturity on composition, biological solubilization and potential revenue. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:35. [PMID: 25798193 PMCID: PMC4367844 DOI: 10.1186/s13068-015-0225-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 02/12/2015] [Indexed: 05/02/2023]
Abstract
BACKGROUND Winter annual crops such as winter rye (Secale cereale L) can produce biomass feedstock on seasonally fallow land that continues to provide high-value food and feed from summer annuals such as corn and soybeans. As energy double crops, winter grasses are likely to be harvested while still immature and thus structurally different from the fully senesced plant material typically used for biofuels. This study investigates the dynamic trends in biomass yield, composition, and biological solubilization over the course of a spring harvest season. RESULTS The water soluble fraction decreased with increasing maturity while total carbohydrate content stayed roughly constant at about 65%. The protein mass fraction decreased with increasing maturity, but was counterbalanced by increasing harvest yield resulting in similar total protein across harvest dates. Winter rye was ground and autoclaved then fermented at 15 g/L total solids by either (1) Clostridium thermocellum or (2) simultaneous saccharification and cofermentation (SSCF) using commercial cellulases (CTec2 and HTec2) and a xylose-fermenting Saccharomyces cerevisiae strain. Solubilization of total carbohydrate dropped significantly as winter rye matured for both C. thermocellum (from approximately 80% to approximately 50%) and SSCF (from approximately 60% to approximately 30%). C. thermocellum achieved total solubilization 33% higher than that of SSCF for the earliest harvest date and 50% higher for the latest harvest date. Potential revenue from protein and bioethanol was stable over a range of different harvest dates, with most of the revenue due to ethanol. In a crop rotation with soybean, recovery of the soluble protein from winter rye could increase per hectare protein production by 20 to 35%. CONCLUSIONS Double-cropping winter rye can produce significant biomass for biofuel production and feed protein as coproduct without competing with the main summer crop. During a 24-day harvest window, the total carbohydrate content remained relatively constant while the early-harvest yielded much higher carbohydrate solubilization for both C. thermocellum fermentation and SSCF. C. thermocellum fermentation achieved higher carbohydrate solubilization than SSCF across all growth stages tested. Although winter rye's yield, composition, and biological reactivity change rapidly in the spring, it offers a substantial and stable income across the harvest season and thus flexibility for the farmer.
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Affiliation(s)
- Xiongjun Shao
- />Thayer School of Engineering at the Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
- />DOE BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Kay DiMarco
- />Penn State University, 225 Agricultural Engineering Building, University Park, PA 16802 USA
| | - Tom L Richard
- />Penn State University, 225 Agricultural Engineering Building, University Park, PA 16802 USA
| | - Lee R Lynd
- />Thayer School of Engineering at the Dartmouth College, 14 Engineering Drive, Hanover, NH 03755 USA
- />DOE BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- />Enchi Corporation, Lebanon, NH 03766 USA
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91
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Recent Advances in Second Generation Ethanol Production by Thermophilic Bacteria. ENERGIES 2014. [DOI: 10.3390/en8010001] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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92
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Draft Genome Sequence of Thermoanaerobacterium saccharolyticum Strain NTOU1, a Thermophilic Bacterium Isolated from Marine Shallow Hydrothermal Vents. GENOME ANNOUNCEMENTS 2014; 2:2/5/e01019-14. [PMID: 25301655 PMCID: PMC4192387 DOI: 10.1128/genomea.01019-14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Thermoanaerobacterium saccharolyticum strain NTOU1 has the ability to utilize several kinds of sugars in lignocellulosic biomass to produce ethanol more efficiently than other bacteria. Here, we report the draft genome sequence and annotation of this strain, which may provide insights into the possible genes and metabolic pathways related to ethanol production.
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93
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Kurylenko OO, Ruchala J, Hryniv OB, Abbas CA, Dmytruk KV, Sibirny AA. Metabolic engineering and classical selection of the methylotrophic thermotolerant yeast Hansenula polymorpha for improvement of high-temperature xylose alcoholic fermentation. Microb Cell Fact 2014; 13:122. [PMID: 25145644 PMCID: PMC4145226 DOI: 10.1186/s12934-014-0122-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Accepted: 08/12/2014] [Indexed: 12/02/2022] Open
Abstract
Background The methylotrophic yeast, Hansenula
polymorpha is an industrially important microorganism, and
belongs to the best studied yeast species with well-developed tools for
molecular research. The complete genome sequence of the strain NCYC495 of
H. polymorpha is publicly available. Some
of the well-studied strains of H. polymorpha
are known to ferment glucose, cellobiose and xylose to ethanol at elevated
temperature (45 – 50°C) with ethanol yield from xylose significantly lower than
that from glucose and cellobiose. Increased yield of ethanol from xylose was
demonstrated following directed metabolic changes but, still the final ethanol
concentration achieved is well below what is considered feasible for economic
recovery by distillation. Results In this work, we describe the construction of strains of H. polymorpha with increased ethanol production
from xylose using an ethanol-non-utilizing strain
(2EthOH−) as the host. The transformants derived
from 2EthOH− overexpressing modified xylose reductase
(XYL1m) and native xylitol dehydrogenase
(XYL2) were isolated. These transformants
produced 1.5-fold more ethanol from xylose than the original host strain. The
additional overexpression of XYL3 gene coding
for xylulokinase, resulted in further 2.3-fold improvement in ethanol production
with no measurable xylitol formed during xylose fermentation. The best ethanol
producing strain obtained by metabolic engineering approaches was subjected to
selection for resistance to the known inhibitor of glycolysis, the anticancer
drug 3-bromopyruvate. The best mutant selected had an ethanol yield of 0.3 g/g
xylose and produced up to 9.8 g of ethanol/l during xylose alcoholic
fermentation at 45°C without correction for ethanol evaporation. Conclusions Our results indicate that xylose conversion to ethanol at elevated temperature
can be significantly improved in H.
polymorpha by combining methods of metabolic engineering and
classical selection.
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Affiliation(s)
| | | | | | | | | | - Andriy A Sibirny
- Department of Molecular Genetics and Biotechnology, Institute of Cell Biology, National Academy of Sciences of Ukraine, Drahomanov Street, 14/16, Lviv 79005, Ukraine.
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Mazzoli R, Bosco F, Mizrahi I, Bayer EA, Pessione E. Towards lactic acid bacteria-based biorefineries. Biotechnol Adv 2014; 32:1216-1236. [PMID: 25087936 DOI: 10.1016/j.biotechadv.2014.07.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 07/14/2014] [Accepted: 07/16/2014] [Indexed: 10/25/2022]
Abstract
Lactic acid bacteria (LAB) have long been used in industrial applications mainly as starters for food fermentation or as biocontrol agents or as probiotics. However, LAB possess several characteristics that render them among the most promising candidates for use in future biorefineries in converting plant-derived biomass-either from dedicated crops or from municipal/industrial solid wastes-into biofuels and high value-added products. Lactic acid, their main fermentation product, is an attractive building block extensively used by the chemical industry, owing to the potential for production of polylactides as biodegradable and biocompatible plastic alternative to polymers derived from petrochemicals. LA is but one of many high-value compounds which can be produced by LAB fermentation, which also include biofuels such as ethanol and butanol, biodegradable plastic polymers, exopolysaccharides, antimicrobial agents, health-promoting substances and nutraceuticals. Furthermore, several LAB strains have ascertained probiotic properties, and their biomass can be considered a high-value product. The present contribution aims to provide an extensive overview of the main industrial applications of LAB and future perspectives concerning their utilization in biorefineries. Strategies will be described in detail for developing LAB strains with broader substrate metabolic capacity for fermentation of cheaper biomass.
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Affiliation(s)
- Roberto Mazzoli
- Laboratory of Biochemistry: Proteomics and Metabolic Engineering of Prokaryotes, Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123 Torino, Italy.
| | - Francesca Bosco
- Department of Applied Science and Technology (DISAT), Politecnico of Torino, Corso Duca degli Abruzzi, 24, 10129 Torino, Italy.
| | - Itzhak Mizrahi
- Institute of Animal Science, ARO, Volcani Research Center, P.O. Box 6Â, Bet Dagan 50-250, Israel.
| | - Edward A Bayer
- Department of Biological Chemistry, the Weizmann Institute of Science, Rehovot 76100 Israel.
| | - Enrica Pessione
- Laboratory of Biochemistry: Proteomics and Metabolic Engineering of Prokaryotes, Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123 Torino, Italy.
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95
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Profile of secreted hydrolases, associated proteins, and SlpA in Thermoanaerobacterium saccharolyticum during the degradation of hemicellulose. Appl Environ Microbiol 2014; 80:5001-11. [PMID: 24907337 DOI: 10.1128/aem.00998-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thermoanaerobacterium saccharolyticum, a Gram-positive thermophilic anaerobic bacterium, grows robustly on insoluble hemicellulose, which requires a specialized suite of secreted and transmembrane proteins. We report here the characterization of proteins secreted by this organism. Cultures were grown on hemicellulose, glucose, xylose, starch, and xylan in pH-controlled bioreactors, and samples were analyzed via spotted microarrays and liquid chromatography-mass spectrometry. Key hydrolases and transporters employed by T. saccharolyticum for growth on hemicellulose were, for the most part, hitherto uncharacterized and existed in two clusters (Tsac_1445 through Tsac_1464 for xylan/xylose and Tsac_1344 through Tsac_1349 for starch). A phosphotransferase system subunit, Tsac_0032, also appeared to be exclusive to growth on glucose. Previously identified hydrolases that showed strong conditional expression changes included XynA (Tsac_1459), XynC (Tsac_0897), and a pullulanase, Apu (Tsac_1342). An omnipresent transcript and protein making up a large percentage of the overall secretome, Tsac_0361, was tentatively identified as the primary S-layer component in T. saccharolyticum, and deletion of the Tsac_0361 gene resulted in gross morphological changes to the cells. The view of hemicellulose degradation revealed here will be enabling for metabolic engineering efforts in biofuel-producing organisms that degrade cellulose well but lack the ability to catabolize C5 sugars.
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96
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Direct conversion of plant biomass to ethanol by engineered Caldicellulosiruptor bescii. Proc Natl Acad Sci U S A 2014; 111:8931-6. [PMID: 24889625 DOI: 10.1073/pnas.1402210111] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Ethanol is the most widely used renewable transportation biofuel in the United States, with the production of 13.3 billion gallons in 2012 [John UM (2013) Contribution of the Ethanol Industry to the Economy of the United States]. Despite considerable effort to produce fuels from lignocellulosic biomass, chemical pretreatment and the addition of saccharolytic enzymes before microbial bioconversion remain economic barriers to industrial deployment [Lynd LR, et al. (2008) Nat Biotechnol 26(2):169-172]. We began with the thermophilic, anaerobic, cellulolytic bacterium Caldicellulosiruptor bescii, which efficiently uses unpretreated biomass, and engineered it to produce ethanol. Here we report the direct conversion of switchgrass, a nonfood, renewable feedstock, to ethanol without conventional pretreatment of the biomass. This process was accomplished by deletion of lactate dehydrogenase and heterologous expression of a Clostridium thermocellum bifunctional acetaldehyde/alcohol dehydrogenase. Whereas wild-type C. bescii lacks the ability to make ethanol, 70% of the fermentation products in the engineered strain were ethanol [12.8 mM ethanol directly from 2% (wt/vol) switchgrass, a real-world substrate] with decreased production of acetate by 38% compared with wild-type. Direct conversion of biomass to ethanol represents a new paradigm for consolidated bioprocessing, offering the potential for carbon neutral, cost-effective, sustainable fuel production.
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97
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Santhi VS, Gupta A, Saranya S, Jebakumar SRD. A novel marine bacterium Isoptericola sp. JS-C42 with the ability to saccharifying the plant biomasses for the aid in cellulosic ethanol production. ACTA ACUST UNITED AC 2014; 1-2:8-14. [PMID: 28435797 PMCID: PMC5381695 DOI: 10.1016/j.btre.2014.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The ever growing demands for food products such as starch and sugar produces; there is a need to find the sources for saccharification for cellulosic bioethanol production. This study provides the first evidence of the lignocellulolytic and saccharifying ability of a marine bacterium namely Isoptericola sp. JS-C42, a Gram positive actinobacterium with the cocci cells embedded on mycelia isolated from the Arabian Sea, India. It exhibited highest filter paper unit effect, endoglucanase, exoglucanase, cellobiohydrolase, β-glucosidase, xylanase and ligninase effect. The hydrolytic potential of the enzymes displayed the efficient saccharification capability of steam pretreated biomass. It was also found to degrade the paddy, sorghum, Acacia mangium and Ficus religiosa into simple reducing sugars by its efficient lignocellulose enzyme complex with limited consumption of sugars. Production of ethanol was also achieved with the Saccharomyces cerevisiae. Overall, it offers a great potential for the cellulosic ethanol production in an economically reliable and eco-friendly point-of-care.
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Affiliation(s)
- Velayudhan Satheeja Santhi
- Department of Molecular Microbiology, School of Biotechnology, Madurai Kamaraj University, Madurai 625 021, Tamil Nadu, India
| | - Ashutosh Gupta
- Department of Molecular Microbiology, School of Biotechnology, Madurai Kamaraj University, Madurai 625 021, Tamil Nadu, India
| | - Somasundaram Saranya
- Department of Molecular Microbiology, School of Biotechnology, Madurai Kamaraj University, Madurai 625 021, Tamil Nadu, India
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98
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Blumer-Schuette SE, Brown SD, Sander KB, Bayer EA, Kataeva I, Zurawski JV, Conway JM, Adams MWW, Kelly RM. Thermophilic lignocellulose deconstruction. FEMS Microbiol Rev 2014; 38:393-448. [DOI: 10.1111/1574-6976.12044] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 08/20/2013] [Accepted: 08/28/2013] [Indexed: 11/28/2022] Open
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99
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Lin PP, Rabe KS, Takasumi JL, Kadisch M, Arnold FH, Liao JC. Isobutanol production at elevated temperatures in thermophilic Geobacillus thermoglucosidasius. Metab Eng 2014; 24:1-8. [PMID: 24721011 DOI: 10.1016/j.ymben.2014.03.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 03/31/2014] [Indexed: 11/19/2022]
Abstract
The potential advantages of biological production of chemicals or fuels from biomass at high temperatures include reduced enzyme loading for cellulose degradation, decreased chance of contamination, and lower product separation cost. In general, high temperature production of compounds that are not native to the thermophilic hosts is limited by enzyme stability and the lack of suitable expression systems. Further complications can arise when the pathway includes a volatile intermediate. Here we report the engineering of Geobacillus thermoglucosidasius to produce isobutanol at 50°C. We prospected various enzymes in the isobutanol synthesis pathway and characterized their thermostabilities. We also constructed an expression system based on the lactate dehydrogenase promoter from Geobacillus thermodenitrificans. With the best enzyme combination and the expression system, 3.3g/l of isobutanol was produced from glucose and 0.6g/l of isobutanol from cellobiose in G. thermoglucosidasius within 48h at 50°C. This is the first demonstration of isobutanol production in recombinant bacteria at an elevated temperature.
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Affiliation(s)
- Paul P Lin
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA
| | - Kersten S Rabe
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Mail Code 210-41, Pasadena, CA 91125, USA
| | - Jennifer L Takasumi
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA
| | - Marvin Kadisch
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Mail Code 210-41, Pasadena, CA 91125, USA
| | - Frances H Arnold
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Mail Code 210-41, Pasadena, CA 91125, USA
| | - James C Liao
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA.
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100
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Abstract
The term "extremophile" was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of "extreme" environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally "hot environments" on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong to the Archaea has definitely made this area of investigation more exciting. Particularly fascinating are their structural and physiological features allowing them to withstand extremely selective environmental conditions. These properties are often due to specific biomolecules (DNA, lipids, enzymes, osmolites, etc.) that have been studied for years as novel sources for biotechnological applications. In some cases (DNA-polymerase, thermostable enzymes), the search and applications successful exceeded preliminary expectations, but certainly further exploitations are still needed.
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