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Li F, Yue TQ, Wang JM, Zhang HB. Externally Supplied Mannitol and Trehalose Boost Phloroglucinol Biosynthesis in Escherichia coli. APPL BIOCHEM MICRO+ 2022. [DOI: 10.1134/s0003683822040093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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2
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Shanmugam KT, Ingram LO. Principles and practice of designing microbial biocatalysts for fuel and chemical production. J Ind Microbiol Biotechnol 2021; 49:6158391. [PMID: 33686428 PMCID: PMC9118985 DOI: 10.1093/jimb/kuab016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 03/03/2021] [Indexed: 11/14/2022]
Abstract
The finite nature of fossil fuels and the environmental impact of its use have raised interest in alternate renewable energy sources. Specifically, non-food carbohydrates, such as lignocellulosic biomass, can be used to produce next generation biofuels, including cellulosic ethanol and other non-ethanol fuels like butanol. However, currently there is no native microorganism that can ferment all lignocellulosic sugars to fuel molecules. Thus, research is focused on engineering improved microbial biocatalysts for production of liquid fuels at high productivity, titer and yield. A clear understanding and application of the basic principles of microbial physiology and biochemistry are crucial to achieve this goal. In this review, we present and discuss the construction of microbial biocatalysts that integrate these principles with ethanol-producing Escherichia coli as an example of metabolic engineering. These principles also apply to fermentation of lignocellulosic sugars to other chemicals that are currently produced from petroleum.
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Affiliation(s)
- K T Shanmugam
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
| | - Lonnie O Ingram
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
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3
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Suo F, Liu J, Chen J, Li X, Solem C, Jensen PR. Efficient Production of Pyruvate Using Metabolically Engineered Lactococcus lactis. Front Bioeng Biotechnol 2021; 8:611701. [PMID: 33490054 PMCID: PMC7815928 DOI: 10.3389/fbioe.2020.611701] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/27/2020] [Indexed: 11/17/2022] Open
Abstract
Microbial production of commodity chemicals has gained increasing attention and most of the focus has been on reducing the production cost. Selecting a suitable microorganism, which can grow rapidly on cheap feedstocks, is of key importance when developing an economically feasible bioprocess. We chose Lactococcus lactis, a well-characterized lactic acid bacterium, as our microbial host to produce pyruvate, which is a commodity chemical with various important applications. Here we report the engineering of Lactococcus lactis into becoming an efficient microbial platform for producing pyruvate. The strain obtained, FS1076 (MG1363 Δ3 ldh Δpta ΔadhE Δals), was able to produce pyruvate as the sole product. Since all the competitive pathways had been knocked out, we achieved growth-coupled production of pyruvate with high yield. More than 80 percent of the carbon flux was directed toward pyruvate, and a final titer of 54.6 g/L was obtained using a fed-batch fermentation setup. By introducing lactose catabolism into FS1076, we obtained the strain FS1080, which was able to generate pyruvate from lactose. We then demonstrated the potential of FS1080 for valorizing lactose contained in dairy side-streams, by achieving a high titer (40.1 g/L) and high yield (78.6%) of pyruvate using residual whey permeate (RWP) as substrate. The results obtained, show that the L. lactis platform is well-suited for transforming lactose in dairy waste into food-grade pyruvate, and the yields obtained are the highest reported in the literature. These results demonstrate that it is possible to achieve sustainable bioconversion of waste products from the dairy industry (RWP) to valuable products.
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Affiliation(s)
- Fan Suo
- Division of Production and Microbiology, National Food Institute, Technical University of Denmark, Lyngby, Denmark
| | - Jianming Liu
- Division of Production and Microbiology, National Food Institute, Technical University of Denmark, Lyngby, Denmark
| | - Jun Chen
- Division of Production and Microbiology, National Food Institute, Technical University of Denmark, Lyngby, Denmark
| | - Xuanji Li
- Section of Microbiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Christian Solem
- Division of Production and Microbiology, National Food Institute, Technical University of Denmark, Lyngby, Denmark
| | - Peter R. Jensen
- Division of Production and Microbiology, National Food Institute, Technical University of Denmark, Lyngby, Denmark
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4
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Cheng HJ, Sun YH, Chang HW, Cui FF, Xue HJ, Shen YB, Wang M, Luo JM. Compatible solutes adaptive alterations in Arthrobacter simplex during exposure to ethanol, and the effect of trehalose on the stress resistance and biotransformation performance. Bioprocess Biosyst Eng 2020; 43:895-908. [PMID: 31993798 DOI: 10.1007/s00449-020-02286-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 01/10/2020] [Indexed: 01/19/2023]
Abstract
Ethanol-tolerant Arthrobacter simplex is desirable since ethanol facilitates hydrophobic substrates dissolution on an industrial scale. Herein, alterations in compatible solutes were investigated under ethanol stress. The results showed that the amount of trehalose and glycerol increased while that of glutamate and proline decreased. The trehalose protectant role was verified and its concentration was positively related to the degree of cell tolerance. otsA, otsB and treS, three trehalose biosynthesis genes in A. simplex, also enhanced Escherichia coli stress tolerance, but the increased tolerance was dependent on the type and level of the stress. A. simplex strains accumulating trehalose showed a higher productivity in systems containing more ethanol and substrate because of better viability. The underlying mechanisms of trehalose were involved in better cell integrity, higher membrane stability, stronger reactive oxygen species scavenging capacity and higher energy level. Therefore, trehalose was a general protectant and the upregulation of its biosynthesis by genetic modification enhanced cell stress tolerance, consequently promoted productivity.
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Affiliation(s)
- Hong-Jin Cheng
- Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, Tianjin Key Lab of Industrial Microbiology, Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, College of Biotechnology, Tianjin University of Science and Technology, 89 PO Box, No 29, St No13 Tianjin Economic-Technological Development Area (TEDA), Tianjin, 300457, People's Republic of China
| | - Ya-Hua Sun
- Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, Tianjin Key Lab of Industrial Microbiology, Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, College of Biotechnology, Tianjin University of Science and Technology, 89 PO Box, No 29, St No13 Tianjin Economic-Technological Development Area (TEDA), Tianjin, 300457, People's Republic of China
| | - Han-Wen Chang
- Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, Tianjin Key Lab of Industrial Microbiology, Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, College of Biotechnology, Tianjin University of Science and Technology, 89 PO Box, No 29, St No13 Tianjin Economic-Technological Development Area (TEDA), Tianjin, 300457, People's Republic of China
| | - Fang-Fang Cui
- Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, Tianjin Key Lab of Industrial Microbiology, Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, College of Biotechnology, Tianjin University of Science and Technology, 89 PO Box, No 29, St No13 Tianjin Economic-Technological Development Area (TEDA), Tianjin, 300457, People's Republic of China
| | - Hai-Jie Xue
- Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, Tianjin Key Lab of Industrial Microbiology, Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, College of Biotechnology, Tianjin University of Science and Technology, 89 PO Box, No 29, St No13 Tianjin Economic-Technological Development Area (TEDA), Tianjin, 300457, People's Republic of China
| | - Yan-Bing Shen
- Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, Tianjin Key Lab of Industrial Microbiology, Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, College of Biotechnology, Tianjin University of Science and Technology, 89 PO Box, No 29, St No13 Tianjin Economic-Technological Development Area (TEDA), Tianjin, 300457, People's Republic of China
| | - Min Wang
- Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, Tianjin Key Lab of Industrial Microbiology, Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, College of Biotechnology, Tianjin University of Science and Technology, 89 PO Box, No 29, St No13 Tianjin Economic-Technological Development Area (TEDA), Tianjin, 300457, People's Republic of China
| | - Jian-Mei Luo
- Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, Tianjin Key Lab of Industrial Microbiology, Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, College of Biotechnology, Tianjin University of Science and Technology, 89 PO Box, No 29, St No13 Tianjin Economic-Technological Development Area (TEDA), Tianjin, 300457, People's Republic of China. .,Ministry of Education Key Laboratory of Molecular Microbiology and Technology, Nankai University, Tianjin, 300071, People's Republic of China.
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5
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Su Y, Guo QQ, Wang S, Zhang X, Wang J. Effects of betaine supplementation on L-threonine fed-batch fermentation by Escherichia coli. Bioprocess Biosyst Eng 2018; 41:1509-1518. [PMID: 30062600 DOI: 10.1007/s00449-018-1978-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 07/02/2018] [Indexed: 12/19/2022]
Abstract
Betaine can act as a stress protectant, methyl donor, or enzyme stabilizer in vitro for the biosynthesis of structurally complex compounds. The performances of betaine type and concentration on the metabolic processes of Escherichia coli JLTHR in a 5-L fermentor were investigated. The results showed that the maximum L-threonine production of 127.3 g/L and glucose conversion percentage of 58.12% was obtained fed with the glucose solution containing 2 g/L betaine hydrochloride, which increased by 14.5 and 6.87% more compared to that of the control, respectively. This study presents an analysis of the metabolic fluxes of E. coli JLTHR for the production of L-threonine with betaine supplementation. When betaine was fed into the fermentation culture medium, the metabolic flux entering into the pentose phosphate pathway (HMP) and biosynthesis route of L-threonine increased by 57.3 and 10.1%, respectively. In conclusion, exogenous addition of betaine was validated to be a feasible and efficacious approach to improve L-threonine production.
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Affiliation(s)
- Yuewen Su
- College of Biological and Agricultural Engineering, Jilin University, Changchun, China.,College of Life Sciences, Jilin University, Changchun, China
| | - Qun-Qun Guo
- College of Biological and Agricultural Engineering, Jilin University, Changchun, China.,College of Life Sciences, Jilin University, Changchun, China
| | - Sen Wang
- College of Biological and Agricultural Engineering, Jilin University, Changchun, China
| | - Xin Zhang
- College of Biological and Agricultural Engineering, Jilin University, Changchun, China
| | - Jian Wang
- College of Biological and Agricultural Engineering, Jilin University, Changchun, China.
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6
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Othoum G, Bougouffa S, Razali R, Bokhari A, Alamoudi S, Antunes A, Gao X, Hoehndorf R, Arold ST, Gojobori T, Hirt H, Mijakovic I, Bajic VB, Lafi FF, Essack M. In silico exploration of Red Sea Bacillus genomes for natural product biosynthetic gene clusters. BMC Genomics 2018; 19:382. [PMID: 29788916 PMCID: PMC5964695 DOI: 10.1186/s12864-018-4796-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 05/14/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The increasing spectrum of multidrug-resistant bacteria is a major global public health concern, necessitating discovery of novel antimicrobial agents. Here, members of the genus Bacillus are investigated as a potentially attractive source of novel antibiotics due to their broad spectrum of antimicrobial activities. We specifically focus on a computational analysis of the distinctive biosynthetic potential of Bacillus paralicheniformis strains isolated from the Red Sea, an ecosystem exposed to adverse, highly saline and hot conditions. RESULTS We report the complete circular and annotated genomes of two Red Sea strains, B. paralicheniformis Bac48 isolated from mangrove mud and B. paralicheniformis Bac84 isolated from microbial mat collected from Rabigh Harbor Lagoon in Saudi Arabia. Comparing the genomes of B. paralicheniformis Bac48 and B. paralicheniformis Bac84 with nine publicly available complete genomes of B. licheniformis and three genomes of B. paralicheniformis, revealed that all of the B. paralicheniformis strains in this study are more enriched in nonribosomal peptides (NRPs). We further report the first computationally identified trans-acyltransferase (trans-AT) nonribosomal peptide synthetase/polyketide synthase (PKS/ NRPS) cluster in strains of this species. CONCLUSIONS B. paralicheniformis species have more genes associated with biosynthesis of antimicrobial bioactive compounds than other previously characterized species of B. licheniformis, which suggests that these species are better potential sources for novel antibiotics. Moreover, the genome of the Red Sea strain B. paralicheniformis Bac48 is more enriched in modular PKS genes compared to B. licheniformis strains and other B. paralicheniformis strains. This may be linked to adaptations that strains surviving in the Red Sea underwent to survive in the relatively hot and saline ecosystems.
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Affiliation(s)
- Ghofran Othoum
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Salim Bougouffa
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Rozaimi Razali
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Ameerah Bokhari
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Soha Alamoudi
- Department of Biology, Science and Arts College, King Abdulaziz University, Rabigh, 21589 Kingdom of Saudi Arabia
| | - André Antunes
- Biology Department, Edge Hill University, L39 4QP, Ormskirk, Lancashire UK
| | - Xin Gao
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Robert Hoehndorf
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Stefan T. Arold
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Takashi Gojobori
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Heribert Hirt
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Ivan Mijakovic
- Department of Biology and Biological Engineering, Division of Systems & Synthetic Biology, Chalmers University of Technology, Kemivägen 10, 41296 Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Vladimir B. Bajic
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Feras F. Lafi
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
- Department of Medical Laboratories, Faculty of Health Sciences, American University of Madaba, PO Box 2882, Madaba, Amman JO-11821 Jordan
| | - Magbubah Essack
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
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7
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Guo S, Yi X, Zhang W, Wu M, Xin F, Dong W, Zhang M, Ma J, Wu H, Jiang M. Inducing hyperosmotic stress resistance in succinate-producing Escherichia coli by using the response regulator DR1558 from Deinococcus radiodurans. Process Biochem 2017. [DOI: 10.1016/j.procbio.2017.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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8
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Affiliation(s)
- Tao Jin
- Iowa State University; Department of Chemical and Biological Engineering; 2114 Sweeney Hall, 618 Bissell Rd. Ames, IA 50011 USA
| | - Jieni Lian
- Iowa State University; Department of Chemical and Biological Engineering; 2114 Sweeney Hall, 618 Bissell Rd. Ames, IA 50011 USA
| | - Laura R. Jarboe
- Iowa State University; Department of Chemical and Biological Engineering; 2114 Sweeney Hall, 618 Bissell Rd. Ames, IA 50011 USA
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Koppolu V, Vasigala VK. Role of Escherichia coli in Biofuel Production. Microbiol Insights 2016; 9:29-35. [PMID: 27441002 PMCID: PMC4946582 DOI: 10.4137/mbi.s10878] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 06/26/2016] [Accepted: 06/28/2016] [Indexed: 12/19/2022] Open
Abstract
Increased energy consumption coupled with depleting petroleum reserves and increased greenhouse gas emissions have renewed our interest in generating fuels from renewable energy sources via microbial fermentation. Central to this problem is the choice of microorganism that catalyzes the production of fuels at high volumetric productivity and yield from cheap and abundantly available renewable energy sources. Microorganisms that are metabolically engineered to redirect renewable carbon sources into desired fuel products are contemplated as best choices to obtain high volumetric productivity and yield. Considering the availability of vast knowledge in genomic and metabolic fronts, Escherichia coli is regarded as a primary choice for the production of biofuels. Here, we reviewed the microbial production of liquid biofuels that have the potential to be used either alone or in combination with the present-day fuels. We specifically highlighted the metabolic engineering and synthetic biology approaches used to improve the production of biofuels from E. coli over the past few years. We also discussed the challenges that still exist for the biofuel production from E. coli and their possible solutions.
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Affiliation(s)
- Veerendra Koppolu
- Scientist, Department of Analytical Biotechnology, MedImmune/AstraZeneca, Gaithersburg, MD, USA.; Former affiliation: Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA
| | - Veneela Kr Vasigala
- Rangaraya Medical College, NTR University of Health Sciences, Kakinada, AP, India
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10
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Zou H, Chen N, Shi M, Xian M, Song Y, Liu J. The metabolism and biotechnological application of betaine in microorganism. Appl Microbiol Biotechnol 2016; 100:3865-76. [PMID: 27005411 DOI: 10.1007/s00253-016-7462-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 03/08/2016] [Accepted: 03/09/2016] [Indexed: 11/29/2022]
Abstract
Glycine betaine (betaine) is widely distributed in nature and can be found in many microorganisms, including bacteria, archaea, and fungi. Due to its particular functions, many microorganisms utilize betaine as a functional chemical and have evolved different metabolic pathways for the biosynthesis and catabolism of betaine. As in animals and plants, the principle role of betaine is to protect microbial cells against drought, osmotic stress, and temperature stress. In addition, the role of betaine in methyl group metabolism has been observed in a variety of microorganisms. Recent studies have shown that betaine supplementation can improve the performance of microbial strains used for the fermentation of lactate, ethanol, lysine, pyruvate, and vitamin B12, during which betaine can act as stress protectant or methyl donor for the biosynthesis of structurally complex compounds. In this review, we summarize the transport, synthesis, catabolism, and functions of betaine in microorganisms and discuss potential engineering strategies that employ betaine as a methyl donor for the biosynthesis of complex secondary metabolites such as a variety of vitamins, coenzymes, and antibiotics. In conclusion, the biocompatibility, C/N ratio, abundance, and comprehensive metabolic information of betaine collectively indicate that this molecule has great potential for broad applications in microbial biotechnology.
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Affiliation(s)
- Huibin Zou
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China. .,CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.
| | - Ningning Chen
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Mengxun Shi
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Mo Xian
- CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Yimin Song
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Junhong Liu
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
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11
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Vorburger T, Nedielkov R, Brosig A, Bok E, Schunke E, Steffen W, Mayer S, Götz F, Möller HM, Steuber J. Role of the Na(+)-translocating NADH:quinone oxidoreductase in voltage generation and Na(+) extrusion in Vibrio cholerae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:473-82. [PMID: 26721205 DOI: 10.1016/j.bbabio.2015.12.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/25/2015] [Accepted: 12/16/2015] [Indexed: 01/05/2023]
Abstract
For Vibrio cholerae, the coordinated import and export of Na(+) is crucial for adaptation to habitats with different osmolarities. We investigated the Na(+)-extruding branch of the sodium cycle in this human pathogen by in vivo (23)Na-NMR spectroscopy. The Na(+) extrusion activity of cells was monitored after adding glucose which stimulated respiration via the Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR). In a V. cholerae deletion mutant devoid of the Na(+)-NQR encoding genes (nqrA-F), rates of respiratory Na(+) extrusion were decreased by a factor of four, but the cytoplasmic Na(+) concentration was essentially unchanged. Furthermore, the mutant was impaired in formation of transmembrane voltage (ΔΨ, inside negative) and did not grow under hypoosmotic conditions at pH8.2 or above. This growth defect could be complemented by transformation with the plasmid encoded nqr operon. In an alkaline environment, Na(+)/H(+) antiporters acidify the cytoplasm at the expense of the transmembrane voltage. It is proposed that, at alkaline pH and limiting Na(+) concentrations, the Na(+)-NQR is crucial for generation of a transmembrane voltage to drive the import of H(+) by electrogenic Na(+)/H(+) antiporters. Our study provides the basis to understand the role of the Na(+)-NQR in pathogenicity of V. cholerae and other pathogens relying on this primary Na(+) pump for respiration.
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Affiliation(s)
- Thomas Vorburger
- Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany
| | - Ruslan Nedielkov
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Alexander Brosig
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Eva Bok
- Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany
| | - Emina Schunke
- Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany
| | - Wojtek Steffen
- Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany
| | - Sonja Mayer
- Interfaculty Institute of Microbiology and Infection Medicine, Department of Microbial Genetics, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Friedrich Götz
- Interfaculty Institute of Microbiology and Infection Medicine, Department of Microbial Genetics, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Heiko M Möller
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
| | - Julia Steuber
- Institute of Microbiology, University of Hohenheim (Stuttgart), Garbenstraße 30, 70599 Stuttgart, Germany.
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Halang P, Vorburger T, Steuber J. Serine 26 in the PomB subunit of the flagellar motor is essential for hypermotility of Vibrio cholerae. PLoS One 2015; 10:e0123518. [PMID: 25874792 PMCID: PMC4398553 DOI: 10.1371/journal.pone.0123518] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 02/19/2015] [Indexed: 11/18/2022] Open
Abstract
Vibrio cholerae is motile by means of its single polar flagellum which is driven by the sodium-motive force. In the motor driving rotation of the flagellar filament, a stator complex consisting of subunits PomA and PomB converts the electrochemical sodium ion gradient into torque. Charged or polar residues within the membrane part of PomB could act as ligands for Na+, or stabilize a hydrogen bond network by interacting with water within the putative channel between PomA and PomB. By analyzing a large data set of individual tracks of swimming cells, we show that S26 located within the transmembrane helix of PomB is required to promote very fast swimming of V. cholerae. Loss of hypermotility was observed with the S26T variant of PomB at pH 7.0, but fast swimming was restored by decreasing the H+ concentration of the external medium. Our study identifies S26 as a second important residue besides D23 in the PomB channel. It is proposed that S26, together with D23 located in close proximity, is important to perturb the hydration shell of Na+ before its passage through a constriction within the stator channel.
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Affiliation(s)
- Petra Halang
- Institute of Microbiology, University of Hohenheim (Stuttgart), Stuttgart, Germany
| | - Thomas Vorburger
- Institute of Microbiology, University of Hohenheim (Stuttgart), Stuttgart, Germany
- * E-mail: (TV); (JS)
| | - Julia Steuber
- Institute of Microbiology, University of Hohenheim (Stuttgart), Stuttgart, Germany
- * E-mail: (TV); (JS)
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13
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Keating DH, Zhang Y, Ong IM, McIlwain S, Morales EH, Grass JA, Tremaine M, Bothfeld W, Higbee A, Ulbrich A, Balloon AJ, Westphall MS, Aldrich J, Lipton MS, Kim J, Moskvin OV, Bukhman YV, Coon JJ, Kiley PJ, Bates DM, Landick R. Aromatic inhibitors derived from ammonia-pretreated lignocellulose hinder bacterial ethanologenesis by activating regulatory circuits controlling inhibitor efflux and detoxification. Front Microbiol 2014; 5:402. [PMID: 25177315 PMCID: PMC4132294 DOI: 10.3389/fmicb.2014.00402] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/17/2014] [Indexed: 11/13/2022] Open
Abstract
Efficient microbial conversion of lignocellulosic hydrolysates to biofuels is a key barrier to the economically viable deployment of lignocellulosic biofuels. A chief contributor to this barrier is the impact on microbial processes and energy metabolism of lignocellulose-derived inhibitors, including phenolic carboxylates, phenolic amides (for ammonia-pretreated biomass), phenolic aldehydes, and furfurals. To understand the bacterial pathways induced by inhibitors present in ammonia-pretreated biomass hydrolysates, which are less well studied than acid-pretreated biomass hydrolysates, we developed and exploited synthetic mimics of ammonia-pretreated corn stover hydrolysate (ACSH). To determine regulatory responses to the inhibitors normally present in ACSH, we measured transcript and protein levels in an Escherichia coli ethanologen using RNA-seq and quantitative proteomics during fermentation to ethanol of synthetic hydrolysates containing or lacking the inhibitors. Our study identified four major regulators mediating these responses, the MarA/SoxS/Rob network, AaeR, FrmR, and YqhC. Induction of these regulons was correlated with a reduced rate of ethanol production, buildup of pyruvate, depletion of ATP and NAD(P)H, and an inhibition of xylose conversion. The aromatic aldehyde inhibitor 5-hydroxymethylfurfural appeared to be reduced to its alcohol form by the ethanologen during fermentation, whereas phenolic acid and amide inhibitors were not metabolized. Together, our findings establish that the major regulatory responses to lignocellulose-derived inhibitors are mediated by transcriptional rather than translational regulators, suggest that energy consumed for inhibitor efflux and detoxification may limit biofuel production, and identify a network of regulators for future synthetic biology efforts.
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Affiliation(s)
- David H Keating
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - Yaoping Zhang
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - Irene M Ong
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - Sean McIlwain
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - Eduardo H Morales
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA ; Department of Biomolecular Chemistry, University of Wisconsin-Madison Madison, WI, USA
| | - Jeffrey A Grass
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA ; Department of Biochemistry, University of Wisconsin-Madison Madison, WI, USA
| | - Mary Tremaine
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - William Bothfeld
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - Alan Higbee
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - Arne Ulbrich
- Department of Chemistry, University of Wisconsin-Madison Madison, WI, USA
| | - Allison J Balloon
- Department of Chemistry, University of Wisconsin-Madison Madison, WI, USA
| | - Michael S Westphall
- Department of Biomolecular Chemistry, University of Wisconsin-Madison Madison, WI, USA ; Department of Chemistry, University of Wisconsin-Madison Madison, WI, USA
| | - Josh Aldrich
- Pacific Northwest National Laboratory Richland, WA, USA
| | - Mary S Lipton
- Pacific Northwest National Laboratory Richland, WA, USA
| | - Joonhoon Kim
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA ; Department of Chemical and Biological Engineering, University of Wisconsin-Madison Madison, WI, USA
| | - Oleg V Moskvin
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - Yury V Bukhman
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - Joshua J Coon
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA ; Department of Biomolecular Chemistry, University of Wisconsin-Madison Madison, WI, USA ; Department of Chemistry, University of Wisconsin-Madison Madison, WI, USA
| | - Patricia J Kiley
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA ; Department of Biomolecular Chemistry, University of Wisconsin-Madison Madison, WI, USA
| | - Donna M Bates
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA
| | - Robert Landick
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison Madison, WI, USA ; Department of Biochemistry, University of Wisconsin-Madison Madison, WI, USA ; Department of Bacteriology, University of Wisconsin-Madison Madison, WI, USA
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Extracellular secretion of β-glucosidase in ethanologenic E. coli enhances ethanol fermentation of cellobiose. Appl Biochem Biotechnol 2014; 174:772-83. [PMID: 25096392 DOI: 10.1007/s12010-014-1108-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 07/22/2014] [Indexed: 01/11/2023]
Abstract
Consolidated bioprocessing of lignocellulose for ethanol production is realized by expressing cellulase enzymes on ethanologenic strain. In this study, an ethanologenic Escherichia coli ZY81 was constructed by integrating pyruvate decarboxylase gene pdc and alcohol dehydrogenase gene adhB from Zymomonas mobilis into the genome of E. coli JM109 to obtain the capability of ethanol production. Then, the β-glucosidase gene bglB from Bacillus polymyxa was cloned and secretively expressed in E. coli ZY81. The recombinant strain E. coli ZY81/bglB showed an obvious activity of β-glucosidase in extracellular location with more than half in periplasmic space. EDTA was found to promote the release of the periplasmic proteins by approximately tenfold. E. coli ZY81/bglB utilized cellobiose as sole carbon source for ethanol production with 33.99 % of theoretical yield.
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15
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McCloskey D, Gangoiti JA, King ZA, Naviaux RK, Barshop BA, Palsson BO, Feist AM. A model-driven quantitative metabolomics analysis of aerobic and anaerobic metabolism in E. coli K-12 MG1655 that is biochemically and thermodynamically consistent. Biotechnol Bioeng 2013; 111:803-15. [PMID: 24249002 DOI: 10.1002/bit.25133] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/30/2013] [Accepted: 10/07/2013] [Indexed: 12/24/2022]
Abstract
The advent of model-enabled workflows in systems biology allows for the integration of experimental data types with genome-scale models to discover new features of biology. This work demonstrates such a workflow, aimed at establishing a metabolomics platform applied to study the differences in metabolomes between anaerobic and aerobic growth of Escherichia coli. Constraint-based modeling was utilized to deduce a target list of compounds for downstream method development. An analytical and experimental methodology was developed and tailored to the compound chemistry and growth conditions of interest. This included the construction of a rapid sampling apparatus for use with anaerobic cultures. The resulting genome-scale data sets for anaerobic and aerobic growth were validated by comparison to previous small-scale studies comparing growth of E. coli under the same conditions. The metabolomics data were then integrated with the E. coli genome-scale metabolic model (GEM) via a sensitivity analysis that utilized reaction thermodynamics to reconcile simulated growth rates and reaction directionalities. This analysis highlighted several optimal network usage inconsistencies, including the incorrect use of the beta-oxidation pathway for synthesis of fatty acids. This analysis also identified enzyme promiscuity for the pykA gene, that is critical for anaerobic growth, and which has not been previously incorporated into metabolic models of E coli.
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Affiliation(s)
- Douglas McCloskey
- Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California, 92093-0412
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Stress responses of the industrial workhorse Bacillus licheniformis to osmotic challenges. PLoS One 2013; 8:e80956. [PMID: 24348917 PMCID: PMC3858371 DOI: 10.1371/journal.pone.0080956] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 10/08/2013] [Indexed: 11/19/2022] Open
Abstract
The Gram-positive endospore-forming bacterium Bacillus licheniformis can be found widely in nature and it is exploited in industrial processes for the manufacturing of antibiotics, specialty chemicals, and enzymes. Both in its varied natural habitats and in industrial settings, B. licheniformis cells will be exposed to increases in the external osmolarity, conditions that trigger water efflux, impair turgor, cause the cessation of growth, and negatively affect the productivity of cell factories in biotechnological processes. We have taken here both systems-wide and targeted physiological approaches to unravel the core of the osmostress responses of B. licheniformis. Cells were suddenly subjected to an osmotic upshift of considerable magnitude (with 1 M NaCl), and their transcriptional profile was then recorded in a time-resolved fashion on a genome-wide scale. A bioinformatics cluster analysis was used to group the osmotically up-regulated genes into categories that are functionally associated with the synthesis and import of osmostress-relieving compounds (compatible solutes), the SigB-controlled general stress response, and genes whose functional annotation suggests that salt stress triggers secondary oxidative stress responses in B. licheniformis. The data set focusing on the transcriptional profile of B. licheniformis was enriched by proteomics aimed at identifying those proteins that were accumulated by the cells through increased biosynthesis in response to osmotic stress. Furthermore, these global approaches were augmented by a set of experiments that addressed the synthesis of the compatible solutes proline and glycine betaine and assessed the growth-enhancing effects of various osmoprotectants. Combined, our data provide a blueprint of the cellular adjustment processes of B. licheniformis to both sudden and sustained osmotic stress.
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17
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Woodruff LB, Boyle NR, Gill RT. Engineering improved ethanol production in Escherichia coli with a genome-wide approach. Metab Eng 2013; 17:1-11. [DOI: 10.1016/j.ymben.2013.01.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/28/2012] [Accepted: 01/17/2013] [Indexed: 11/29/2022]
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18
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Wu W, Fan Z. A general inhibition kinetics model for ethanol production using a novel carbon source: sodium gluconate. Bioprocess Biosyst Eng 2013; 36:1631-40. [DOI: 10.1007/s00449-013-0938-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 02/25/2013] [Indexed: 11/24/2022]
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19
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Disruption of ptsG gene and manXYZ operon of ethanol-producing Escherichia coli KO11: Effects on glucose and xylose utilization and ethanol production. J Biosci Bioeng 2012; 113:608-10. [DOI: 10.1016/j.jbiosc.2011.12.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2011] [Revised: 12/08/2011] [Accepted: 12/30/2011] [Indexed: 11/22/2022]
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20
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Complex physiology and compound stress responses during fermentation of alkali-pretreated corn stover hydrolysate by an Escherichia coli ethanologen. Appl Environ Microbiol 2012; 78:3442-57. [PMID: 22389370 DOI: 10.1128/aem.07329-11] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The physiology of ethanologenic Escherichia coli grown anaerobically in alkali-pretreated plant hydrolysates is complex and not well studied. To gain insight into how E. coli responds to such hydrolysates, we studied an E. coli K-12 ethanologen fermenting a hydrolysate prepared from corn stover pretreated by ammonia fiber expansion. Despite the high sugar content (∼6% glucose, 3% xylose) and relatively low toxicity of this hydrolysate, E. coli ceased growth long before glucose was depleted. Nevertheless, the cells remained metabolically active and continued conversion of glucose to ethanol until all glucose was consumed. Gene expression profiling revealed complex and changing patterns of metabolic physiology and cellular stress responses during an exponential growth phase, a transition phase, and the glycolytically active stationary phase. During the exponential and transition phases, high cell maintenance and stress response costs were mitigated, in part, by free amino acids available in the hydrolysate. However, after the majority of amino acids were depleted, the cells entered stationary phase, and ATP derived from glucose fermentation was consumed entirely by the demands of cell maintenance in the hydrolysate. Comparative gene expression profiling and metabolic modeling of the ethanologen suggested that the high energetic cost of mitigating osmotic, lignotoxin, and ethanol stress collectively limits growth, sugar utilization rates, and ethanol yields in alkali-pretreated lignocellulosic hydrolysates.
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21
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Zhang H, Chong H, Ching CB, Jiang R. Random mutagenesis of global transcription factor cAMP receptor protein for improved osmotolerance. Biotechnol Bioeng 2011; 109:1165-72. [DOI: 10.1002/bit.24411] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 11/07/2011] [Accepted: 12/08/2011] [Indexed: 11/08/2022]
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22
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Effect of culture operating conditions on succinate production in a multiphase fed-batch bioreactor using an engineered Escherichia coli strain. Appl Microbiol Biotechnol 2011; 92:499-508. [DOI: 10.1007/s00253-011-3314-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 04/11/2011] [Accepted: 04/13/2011] [Indexed: 10/18/2022]
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Affiliation(s)
- Tiangang Liu
- Department of Chemistry, Stanford University, Stanford, California 94305
| | - Chaitan Khosla
- Department of Chemistry, Stanford University, Stanford, California 94305
- Department of Chemical Engineering, Stanford University, Stanford, California 94305
- Department of Biochemistry, Stanford University, Stanford, California 94305;
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Ma R, Zhang Y, Hong H, Lu W, Lin M, Chen M, Zhang W. Improved osmotic tolerance and ethanol production of ethanologenic Escherichia coli by IrrE, a global regulator of radiation-resistance of Deinococcus radiodurans. Curr Microbiol 2010; 62:659-64. [PMID: 20959988 DOI: 10.1007/s00284-010-9759-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Accepted: 09/03/2010] [Indexed: 12/01/2022]
Abstract
Successful fermentations to produce ethanol using ethanologenic Escherichia coli require tolerance to high concentrations of sugars. Here we demonstrate that irrE, encoding a regulatory protein for radiation-resistance in Deinococcus radiodurans, conferred improved osmotic stress tolerance to E. coli. Expression of the gene protected E. coli cells against 25% glucose or xylose, acid shock. It also markedly improved cellular viability, the transcriptional levels of trehalose biosynthetic genes (otsBA) and trehalose content in the IrrE-expressing strain compared with the control strain. IrrE expression also enhanced the expression levels and enzymatic activities of PDC and ADHB as well as ethanol production. Our results suggest that IrrE could potentially be used to improve osmotic stress tolerance and ethanol production in ethanologenic strains.
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Affiliation(s)
- Ruiqiang Ma
- College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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25
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Jia K, Zhang Y, Li Y. Systematic engineering of microorganisms to improve alcohol tolerance. Eng Life Sci 2010. [DOI: 10.1002/elsc.201000076] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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26
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Zhu Y, Eiteman MA, Lee SA, Altman E. Conversion of glycerol to pyruvate by Escherichia coli using acetate- and acetate/glucose-limited fed-batch processes. J Ind Microbiol Biotechnol 2009; 37:307-12. [PMID: 20012884 DOI: 10.1007/s10295-009-0675-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Accepted: 11/25/2009] [Indexed: 11/26/2022]
Abstract
We report the conversion of glycerol to pyruvate by E. coli ALS929 containing knockouts in the genes encoding for phosphoenolpyruvate synthase, lactate dehydrogenase, pyruvate formate lyase, the pyruvate dehydrogenase complex, and pyruvate oxidase. As a result of these knockouts, ALS929 has a growth requirement of acetate for the generation of acetyl CoA. In steady-state chemostat experiments using excess glycerol and limited by acetate, lower growth rates favored the formation of pyruvate from glycerol (0.60 g/g at 0.10 h(-1) versus 0.44 g/g at 0.25 h(-1)), while higher growth rates resulted in the maximum specific glycerol consumption rate (0.85 g/g h at 0.25 h(-1) versus 0.59 g/g h at 0.10 h(-1)). The presence of glucose significantly improved pyruvate productivity and yield from glycerol (0.72 g/g at 0.10 h(-1)). In fed-batch studies using exponential acetate/glucose-limited feeding at a constant growth rate of 0.10 h(-1), the final pyruvate concentration achieved was about 40 g/L in 36 h. A derivative of ALS929 which additionally knocked out methylglyoxal synthase did not further increase pyruvate productivity or yield, indicating that pyruvate formation was not limited by accumulation of methylglyoxal.
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Affiliation(s)
- Yihui Zhu
- Center for Molecular BioEngineering, Department of Biological and Agricultural Engineering, University of Georgia, Athens, GA 30602, USA
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27
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Mills TY, Sandoval NR, Gill RT. Cellulosic hydrolysate toxicity and tolerance mechanisms in Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS 2009; 2:26. [PMID: 19832972 PMCID: PMC2770041 DOI: 10.1186/1754-6834-2-26] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Accepted: 10/15/2009] [Indexed: 05/03/2023]
Abstract
The sustainable production of biofuels will require the efficient utilization of lignocellulosic biomass. A key barrier involves the creation of growth-inhibitory compounds by chemical pretreatment steps, which ultimately reduce the efficiency of fermentative microbial biocatalysts. The primary toxins include organic acids, furan derivatives, and phenolic compounds. Weak acids enter the cell and dissociate, resulting in a drop in intracellular pH as well as various anion-specific effects on metabolism. Furan derivatives, dehydration products of hexose and pentose sugars, have been shown to hinder fermentative enzyme function. Phenolic compounds, formed from lignin, can disrupt membranes and are hypothesized to interfere with the function of intracellular hydrophobic targets. This review covers mechanisms of toxicity and tolerance for these compounds with a specific focus on the important industrial organism Escherichia coli. Recent efforts to engineer E. coli for improved tolerance to these toxins are also discussed.
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Affiliation(s)
- Tirzah Y Mills
- Department of Chemical and Biological Engineering, UCB424/ECCH120, University of Colorado, Boulder, CO 80309, USA
| | - Nicholas R Sandoval
- Department of Chemical and Biological Engineering, UCB424/ECCH120, University of Colorado, Boulder, CO 80309, USA
| | - Ryan T Gill
- Department of Chemical and Biological Engineering, UCB424/ECCH120, University of Colorado, Boulder, CO 80309, USA
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28
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Engineering for biofuels: exploiting innate microbial capacity or importing biosynthetic potential? Nat Rev Microbiol 2009; 7:715-23. [DOI: 10.1038/nrmicro2186] [Citation(s) in RCA: 304] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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29
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Vorburger T, Stein A, Ziegler U, Kaim G, Steuber J. Functional role of a conserved aspartic acid residue in the motor of the Na(+)-driven flagellum from Vibrio cholerae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1198-204. [PMID: 19501041 DOI: 10.1016/j.bbabio.2009.05.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 05/20/2009] [Accepted: 05/20/2009] [Indexed: 11/15/2022]
Abstract
The flagellar motor consists of a rotor and a stator and couples the flux of cations (H(+) or Na(+)) to the generation of the torque necessary to drive flagellum rotation. The inner membrane proteins PomA and PomB are stator components of the Na(+)-driven flagellar motor from Vibrio cholerae. Affinity-tagged variants of PomA and PomB were co-expressed in trans in the non-motile V. cholerae pomAB deletion strain to study the role of the conserved D23 in the transmembrane helix of PomB. At pH 9, the D23E variant restored motility to 100% of that observed with wild type PomB, whereas the D23N variant resulted in a non-motile phenotype, indicating that a carboxylic group at position 23 in PomB is important for flagellum rotation. Motility tests at decreasing pH revealed a pronounced decline of flagellar function with a motor complex containing the PomB-D23E variant. It is suggested that the protonation state of the glutamate residue at position 23 determines the performance of the flagellar motor by altering the affinity of Na(+) to PomB. The conserved aspartate residue in the transmembrane helix of PomB and its H(+)-dependent homologs might act as a ligand for the coupling cation in the flagellar motor.
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Andersson C, Helmerius J, Hodge D, Berglund KA, Rova U. Inhibition of succinic acid production in metabolically engineeredEscherichia coliby neutralizing agent, organic acids, and osmolarity. Biotechnol Prog 2009; 25:116-23. [DOI: 10.1002/btpr.127] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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31
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High glycolytic flux improves pyruvate production by a metabolically engineered Escherichia coli strain. Appl Environ Microbiol 2008; 74:6649-55. [PMID: 18806005 DOI: 10.1128/aem.01610-08] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report pyruvate formation in Escherichia coli strain ALS929 containing mutations in the aceEF, pfl, poxB, pps, and ldhA genes which encode, respectively, the pyruvate dehydrogenase complex, pyruvate formate lyase, pyruvate oxidase, phosphoenolpyruvate synthase, and lactate dehydrogenase. The glycolytic rate and pyruvate productivity were compared using glucose-, acetate-, nitrogen-, or phosphorus-limited chemostats at a growth rate of 0.15 h(-1). Of these four nutrient limitation conditions, growth under acetate limitation resulted in the highest glycolytic flux (1.60 g/g . h), pyruvate formation rate (1.11 g/g h), and pyruvate yield (0.70 g/g). Additional mutations in atpFH and arcA (strain ALS1059) further elevated the steady-state glycolytic flux to 2.38 g/g h in an acetate-limited chemostat, with heterologous NADH oxidase expression causing only modest additional improvement. A fed-batch process with strain ALS1059 using defined medium with 5 mM betaine as osmoprotectant and an exponential feeding rate of 0.15 h(-1) achieved 90 g/liter pyruvate, with an overall productivity of 2.1 g/liter h and yield of 0.68 g/g.
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32
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Yomano LP, York SW, Zhou S, Shanmugam KT, Ingram LO. Re-engineering Escherichia coli for ethanol production. Biotechnol Lett 2008; 30:2097-103. [DOI: 10.1007/s10529-008-9821-3] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 07/23/2008] [Accepted: 08/11/2008] [Indexed: 11/29/2022]
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33
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Peterson JD, Ingram LO. Anaerobic respiration in engineered Escherichia coli with an internal electron acceptor to produce fuel ethanol. Ann N Y Acad Sci 2008; 1125:363-72. [PMID: 18378606 DOI: 10.1196/annals.1419.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Environmental concerns and unease with U.S. dependence on foreign oil have renewed interest in converting biomass into fuel ethanol. The volume of plant matter available makes lignocellulose conversion to ethanol desirable, although no one isolated organism has been shown to break bonds in lignocellulose and efficiently metabolize resulting sugars into one product. This work reviews directed engineering coupled with metabolic evolution resulting in microbial biocatalysts that produce up to 45 g L(-1) ethanol in 48 hours in a simple mineral salts medium and that convert various compounds of lignocellulosic materials to ethanol. Mutations contributing to ethanologenesis are discussed along with adding enzymatic capabilities to existing biocatalysts in order to decrease the commercial enzymes required to reduce plant matter into fermentable sugars.
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34
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Zhang L, Lang Y, Wang C, Nagata S. Promoting effect of compatible solute ectoine on the ethanol fermentation by Zymomonas mobilis CICC10232. Process Biochem 2008. [DOI: 10.1016/j.procbio.2008.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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35
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Jantama K, Haupt M, Svoronos SA, Zhang X, Moore J, Shanmugam K, Ingram L. Combining metabolic engineering and metabolic evolution to develop nonrecombinant strains ofEscherichia coli C that produce succinate and malate. Biotechnol Bioeng 2008; 99:1140-53. [DOI: 10.1002/bit.21694] [Citation(s) in RCA: 262] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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36
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Yanase H, Sato D, Yamamoto K, Matsuda S, Yamamoto S, Okamoto K. Genetic engineering of Zymobacter palmae for production of ethanol from xylose. Appl Environ Microbiol 2007; 73:2592-9. [PMID: 17308178 PMCID: PMC1855588 DOI: 10.1128/aem.02302-06] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Accepted: 02/12/2007] [Indexed: 11/20/2022] Open
Abstract
Its metabolic characteristics suggest that Zymobacter palmae gen. nov., sp. nov. could serve as a useful new ethanol-fermenting bacterium, but its biotechnological exploitation will require certain genetic modifications. We therefore engineered Z. palmae so as to broaden the range of its fermentable sugar substrates to include the pentose sugar xylose. The Escherichia coli genes encoding the xylose catabolic enzymes xylose isomerase, xylulokinase, transaldolase, and transketolase were introduced into Z. palmae, where their expression was driven by the Zymomonas mobilis glyceraldehyde-3-phosphate dehydrogenase promoter. When cultured with 40 g/liter xylose, the recombinant Z. palmae strain was able to ferment 16.4 g/liter xylose within 5 days, producing 91% of the theoretical yield of ethanol with no accumulation of organic acids as metabolic by-products. Notably, xylose acclimation enhanced both the expression of xylose catabolic enzymes and the rate of xylose uptake into recombinant Z. palmae, which enabled the acclimated organism to completely and simultaneously ferment a mixture of 40 g/liter glucose and 40 g/liter xylose within 8 h, producing 95% of the theoretical yield of ethanol. Thus, efficient fermentation of a mixture of glucose and xylose to ethanol can be accomplished by using Z. palmae expressing E. coli xylose catabolic enzymes.
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Affiliation(s)
- Hideshi Yanase
- Department of Biotechnology, Faculty of Engineering, Tottori University, 4-101 Koyamacho-Minami, Tottori, Tottori, Japan.
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Okuda N, Ninomiya K, Takao M, Katakura Y, Shioya S. Microaeration enhances productivity of bioethanol from hydrolysate of waste house wood using ethanologenic Escherichia coli KO11. J Biosci Bioeng 2007; 103:350-7. [PMID: 17502277 DOI: 10.1263/jbb.103.350] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Accepted: 01/17/2007] [Indexed: 11/17/2022]
Abstract
This is the first study showing the successful application of waste house wood (WHW) to the pilot-scale production of bioethanol by hydrolysis using diluted acid and fermentation using the ethanologenic recombinant Escherichia coli KO11. The major sugars in the WHW hydrolysate were glucose, mannose and xylose; the percentages were approximately 35%, 35% and 20% (w/w), respectively. In anaerobic fermentation using a 5-l reactor in which the oxygen transfer rate (OTR) was 0 mmol/(l x h), KO11 consumed only 25% of the xylose in the WHW hydrolysate over the examined fermentation time of 100 h; however, hexoses such as glucose and mannose were consumed completely. Microaeration at an OTR of 4 mmol/(l x h) enhanced the xylose utilization ratio of KO11 to 100%, at which the ethanol concentration was 35.4 g/l and the ethanol yield was 0.42, although the maximum ethanol concentrations were 28.8 and 26.6 g/l at OTRs of 0 mmol/(l x h) and 15 mmol/(l x h), respectively. Moreover, this microaerobic fermentation at OTR of 4 mmol/(l x h) was applied to 1000-l scale bioethanol production using the WHW hydrolysate. The xylose utilization ratio reached 100% and the ethanol yield was determined to be 0.45 for a 63-h fermentation, which were comparable to those obtained from the laboratory-scale fermentation.
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Affiliation(s)
- Naoyuki Okuda
- Bio Business Development Group, Tsukishima Kikai Co., Ltd., 17-15 Tsukuda 2-Chome, Chuo-ku, Tokyo 104-0051, Japan
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Lin PC, Türk K, Häse CC, Fritz G, Steuber J. Quinone reduction by the Na+-translocating NADH dehydrogenase promotes extracellular superoxide production in Vibrio cholerae. J Bacteriol 2007; 189:3902-8. [PMID: 17322313 PMCID: PMC1913329 DOI: 10.1128/jb.01651-06] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The pathogenicity of Vibrio cholerae is influenced by sodium ions which are actively extruded from the cell by the Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR). To study the function of the Na(+)-NQR in the respiratory chain of V. cholerae, we examined the formation of organic radicals and superoxide in a wild-type strain and a mutant strain lacking the Na(+)-NQR. Upon reduction with NADH, an organic radical was detected in native membranes by electron paramagnetic resonance spectroscopy which was assigned to ubisemiquinones generated by the Na(+)-NQR. The radical concentration increased from 0.2 mM at 0.08 mM Na(+) to 0.4 mM at 14.7 mM Na(+), indicating that the concentration of the coupling cation influences the redox state of the quinone pool in V. cholerae membranes. During respiration, V. cholerae cells produced extracellular superoxide with a specific activity of 10.2 nmol min(-1) mg(-1) in the wild type compared to 3.1 nmol min(-1) mg(-1) in the NQR deletion strain. Raising the Na(+) concentration from 0.1 to 5 mM increased the rate of superoxide formation in the wild-type V. cholerae strain by at least 70%. Rates of respiratory H(2)O(2) formation by wild-type V. cholerae cells (30.9 nmol min(-1) mg(-1)) were threefold higher than rates observed with the mutant strain lacking the Na(+)-NQR (9.7 nmol min(-1) mg(-1)). Our study shows that environmental Na(+) could stimulate ubisemiquinone formation by the Na(+)-NQR and hereby enhance the production of reactive oxygen species formed during the autoxidation of reduced quinones.
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Affiliation(s)
- Po-Chi Lin
- Biochemisches Institut, Universität Zürich, CH-8057 Zürich, Switzerland
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Kim Y, Ingram LO, Shanmugam KT. Construction of an Escherichia coli K-12 mutant for homoethanologenic fermentation of glucose or xylose without foreign genes. Appl Environ Microbiol 2007; 73:1766-71. [PMID: 17259366 PMCID: PMC1828829 DOI: 10.1128/aem.02456-06] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Conversion of lignocellulosic feedstocks to ethanol requires microorganisms that effectively ferment both hexose and pentose sugars. Towards this goal, recombinant organisms have been developed in which heterologous genes were added to platform organisms such as Saccharomyces cerevisiae, Zymomonas mobilis, and Escherichia coli. Using a novel approach that relies only on native enzymes, we have developed a homoethanologenic alternative, Escherichia coli strain SE2378. This mutant ferments glucose or xylose to ethanol with a yield of 82% under anaerobic conditions. An essential mutation in this mutant was mapped within the pdh operon (pdhR aceEF lpd), which encodes components of the pyruvate dehydrogenase complex. Anaerobic ethanol production by this mutant is apparently the result of a novel pathway that combines the activities of pyruvate dehydrogenase (typically active during aerobic, oxidative metabolism) with the fermentative alcohol dehydrogenase.
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Affiliation(s)
- Youngnyun Kim
- Department of Microbiology and Cell Science, Box 110700, University of Florida, Gainesville, FL 32611, USA
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Jarboe LR, Grabar TB, Yomano LP, Shanmugan KT, Ingram LO. Development of ethanologenic bacteria. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2007; 108:237-61. [PMID: 17665158 DOI: 10.1007/10_2007_068] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The utilization of lignocellulosic biomass as a petroleum alternative faces many challenges. This work reviews recent progress in the engineering of Escherichia coli and Klebsiella oxytoca to produce ethanol from biomass with minimal nutritional supplementation. A combination of directed engineering and metabolic evolution has resulted in microbial biocatalysts that produce up to 45 g L(-1) ethanol in 48 h in a simple mineral salts medium, and convert various lignocellulosic materials to ethanol. Mutations contributing to ethanologenesis are discussed. The ethanologenic biocatalyst design approach was applied to other commodity chemicals, including optically pure D: (-)- and L: (+)-lactic acid, succinate and L: -alanine with similar success. This review also describes recent progress in growth medium development, the reduction of hemicellulose hydrolysate toxicity and reduction of the demand for fungal cellulases.
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Affiliation(s)
- L R Jarboe
- Department of Microbiology and Cell Science, University of Florida, 32611, Gainesville, FL 32611, USA.
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41
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Martinez A, Grabar TB, Shanmugam KT, Yomano LP, York SW, Ingram LO. Low salt medium for lactate and ethanol production by recombinant Escherichia coli B. Biotechnol Lett 2006; 29:397-404. [PMID: 17160622 DOI: 10.1007/s10529-006-9252-y] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 10/31/2006] [Indexed: 10/23/2022]
Abstract
Individual nutrient salts were experimentally varied to determine the minimum requirements for efficient L (+)-lactate production by recombinant strains of Escherichia coli B. Based on these results, AM1 medium was formulated with low levels of alkali metals (4.5 mM and total salts (4.2 g l(-1)). This medium was equally effective for ethanol production from xylose and lactate production from glucose with average productivities of 18-19 mmol l(-1) h(-1) for both (initial 48 h of fermentation).
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Affiliation(s)
- Alfredo Martinez
- Institute of Biotechnology, National Autonomous University of Mexico, Cuernavaca, Morelos, Mexico
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Miller EN, Ingram LO. Combined effect of betaine and trehalose on osmotic tolerance of Escherichia coli in mineral salts medium. Biotechnol Lett 2006; 29:213-7. [PMID: 17151959 DOI: 10.1007/s10529-006-9226-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 09/26/2006] [Indexed: 11/29/2022]
Abstract
In mineral salts medium, supplementing with betaine in combination with increased production of endogenous osmoprotectant from a second copy of the trehalose biosynthetic genes (otsBA) improved growth of E. coli and increased the MIC for xylose, glucose, sodium lactate and NaCl. With these compounds, this combination was more effective than either betaine or trehalose alone. With succinate, this combination was no more effective than betaine alone. Neither approach improved tolerance to ethanol. A combination of betaine and increased trehalose may improve strain productivity for many bioproducts by promoting growth in the presence of high sugar concentrations.
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Affiliation(s)
- E N Miller
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
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Qureshi N, Dien B, Nichols N, Saha B, Cotta M. Genetically Engineered Escherichia Coli for Ethanol Production from Xylose. FOOD AND BIOPRODUCTS PROCESSING 2006. [DOI: 10.1205/fbp.05038] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Zhou S, Grabar TB, Shanmugam KT, Ingram LO. Betaine Tripled the Volumetric Productivity of d(-)-lactate by Escherichia coli Strain SZ132 in Mineral Salts Medium. Biotechnol Lett 2006; 28:671-6. [PMID: 16642307 DOI: 10.1007/s10529-006-0033-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Accepted: 02/07/2006] [Indexed: 10/24/2022]
Abstract
Osmotic stress restricts glycolytic flux, growth (rate and yield), D-lactate productivity, and D-lactate tolerance in Escherichia coli B strain SZ132 during batch fermentation in mineral salts medium with 10% (w/v) sugar. Addition of 1 mM: betaine, a non-metabolized protective osmolyte, doubled cell yield, increased specific productivity of D-lactate and glycolytic flux by 50%, and tripled volumetric productivity (from 8.6 to 25.7 mmol l(-1) h(-1); 0.8 to 2.3 g l(-1) h(-1)). Glycolytic flux and specific productivity in mineral salts medium with betaine exceeded that in Luria broth, substantially eliminating the need for complex nutrients during D-lactate production. In mineral salts medium supplemented with betaine, SZ132 produced approximately 1 mol D-lactate (90 g) per 100 g sugar (glucose or sucrose).
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Affiliation(s)
- S Zhou
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA
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Purvis JE, Yomano LP, Ingram LO. Enhanced trehalose production improves growth of Escherichia coli under osmotic stress. Appl Environ Microbiol 2005; 71:3761-9. [PMID: 16000787 PMCID: PMC1168978 DOI: 10.1128/aem.71.7.3761-3769.2005] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The biosynthesis of trehalose has been previously shown to serve as an important osmoprotectant and stress protectant in Escherichia coli. Our results indicate that overproduction of trehalose (integrated lacI-Ptac-otsBA) above the level produced by the native regulatory system can be used to increase the growth of E. coli in M9-2% glucose medium at 37 degrees C to 41 degrees C and to increase growth at 37 degrees C in the presence of a variety of osmotic-stress agents (hexose sugars, inorganic salts, and pyruvate). Smaller improvements were noted with xylose and some fermentation products (ethanol and pyruvate). Based on these results, overproduction of trehalose may be a useful trait to include in biocatalysts engineered for commodity chemicals.
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Affiliation(s)
- J E Purvis
- Dept. of Microbiology and Cell Science, Bldg. 981 Museum Road, IFAS, P.O. Box 110700, University of Florida, Gainesville, FL 32611, USA
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Lee K. A media design program for lactic acid production coupled with extraction by electrodialysis. BIORESOURCE TECHNOLOGY 2005; 96:1505-10. [PMID: 15939279 DOI: 10.1016/j.biortech.2004.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2003] [Revised: 11/12/2004] [Accepted: 11/18/2004] [Indexed: 05/02/2023]
Abstract
The aim of this study was to investigate industrial media for lactic acid fermentation to reduce the cost of nitrogen sources. Corn steep liquor (CSL) was successfully used at 5% (v/v) in batch fermentations. Use of soluble CSL improved the productivity approximately 20% with an advantage of clearer fermentation broth. Yeast extract (YE)-complemented CSL media further increased the productivity. It was found that 3.1 g L(-1) yeast extract and 5% CSL could be an effective substitute for 15 g L(-1) yeast extract in 10% glucose medium. Spent brewery yeast was also used as a sole nitrogen source equivalent to 5% CSL. Lactic acid was recovered by electrodialysis from the cell free broth. Depleted cell free broth supplemented with 5 g L(-1) of yeast extract performed reasonably in batch cultures. Reuse of the fermentation broth may reduce the cost of raw materials as well as minimize the fermentation wastes.
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Affiliation(s)
- KiBeom Lee
- Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), South Korea.
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Causey TB, Shanmugam KT, Yomano LP, Ingram LO. Engineering Escherichia coli for efficient conversion of glucose to pyruvate. Proc Natl Acad Sci U S A 2004; 101:2235-40. [PMID: 14982993 PMCID: PMC356934 DOI: 10.1073/pnas.0308171100] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Escherichia coli TC44, a derivative of W3110, was engineered for the production of pyruvate from glucose by combining mutations to minimize ATP yield, cell growth, and CO2 production (DeltaatpFH DeltaadhE DeltasucA) with mutations that eliminate acetate production [poxB::FRT (FLP recognition target) DeltaackA] and fermentation products (DeltafocA-pflB DeltafrdBC DeltaldhA DeltaadhE). In mineral salts medium containing glucose as the sole carbon source, strain TC44(DeltafocA-pflB DeltafrdBC DeltaldhA DeltaatpFH DeltaadhE DeltasucA poxB::FRT DeltaackA) converted glucose to pyruvate with a yield of 0.75 g of pyruvate per g of glucose (77.9% of theoretical yield; 1.2 g of pyruvate liters(-1).h(-1)). A maximum of 749 mM pyruvate was produced with excess glucose. Glycolytic flux was >50% faster for TC44 producing pyruvate than for the wild-type W3110 during fully aerobic metabolism. The tolerance of E. coli to such drastic changes in metabolic flow and energy production implies considerable elasticity in permitted pool sizes for key metabolic intermediates such as pyruvate and acetyl-CoA. In strain TC44, pyruvate yield, pyruvate titer, and the rate of pyruvate production in mineral salts medium were equivalent or better than previously reported for other biocatalysts (yeast and bacteria) requiring complex vitamin feeding strategies and complex nutrients. TC44 offers the potential to improve the economics of pyruvate production by reducing the costs of materials, product purification, and waste disposal.
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Affiliation(s)
- T B Causey
- Department of Microbiology and Cell Science, University of Florida, Box 110700, Gainesville, FL 32611, USA
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