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Ahmadpanah H, Motamedian E, Mardanpour MM. Metabolic regulation boosts bioelectricity generation in Zymomonas mobilis microbial fuel cell, surpassing ethanol production. Sci Rep 2023; 13:20673. [PMID: 38001147 PMCID: PMC10673858 DOI: 10.1038/s41598-023-47846-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 11/19/2023] [Indexed: 11/26/2023] Open
Abstract
Zymomonas mobilis (Z. mobilis), a bacterium known for its ethanol production capabilities, can also generate electricity by transitioning from ethanol production to electron generation. The purpose of this study is to investigate the ability of Z. mobilis to produce bioelectricity when utilized as a biocatalyst in a single-chamber microbial fuel cell (MFC). Given the bacterium's strong inclination towards ethanol production, a metabolic engineering strategy was devised to identify key reactions responsible for redirecting electrons from ethanol towards electricity generation. To evaluate the electroactivity of cultured Z. mobilis and its ethanol production in the presence of regulators, the reduction of soluble Fe(III) was utilized. Among the regulators tested, CuCl2 demonstrated superior effectiveness. Consequently, the MFC was employed to analyze the electrochemical properties of Z. mobilis using both a minimal and modified medium. By modifying the bacterial medium, the maximum current and power density of the MFC fed with Z. mobilis increased by more than 5.8- and sixfold, respectively, compared to the minimal medium. These findings highlight the significant impact of metabolic redirection in enhancing the performance of MFCs. Furthermore, they establish Z. mobilis as an active electrogenesis microorganism capable of power generation in MFCs.
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Affiliation(s)
- Hananeh Ahmadpanah
- Department of Biotechnology, Faculty of Chemical Engineering, Tarbiat Modares University, P.O. Box 14115‑143, Tehran, Iran
| | - Ehsan Motamedian
- Department of Biotechnology, Faculty of Chemical Engineering, Tarbiat Modares University, P.O. Box 14115‑143, Tehran, Iran.
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Improved Hydrogen Peroxide Stress Resistance of Zymomonas mobilis NADH Dehydrogenase (ndh) and Alcohol Dehydrogenase (adhB) Mutants. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8060289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Unintended shifts in stress resistance of microbial strains with engineered central metabolism may impact their growth and production performance under oxidative, lignocellulosic, solvent, and other stress conditions, and as such, must be taken into account in bioprocess design. In the present work, we studied oxidative stress resistance in mutant strains of the facultatively anaerobic, ethanologenic bacterium Zymomonas mobilis with modified respiratory (inactivated NADH dehydrogenase Ndh, by disruption of ndh) and ethanologenic (inactivated iron-containing alcohol dehydrogenase isoenzyme ADH II, by disruption of adhB) catabolism, using exogenously added H2O2 in the concentration range of 2–6 mM as the oxidative stressor. Both mutations improved H2O2 resistance and enhanced catalase activity by a factor of 2–5, while the overexpression of Ndh had an opposite effect. Strains with a catalase-negative background were unable to grow already at 1 mM hydrogen peroxide, and their H2O2 resistance did not depend on AdhB or Ndh expression levels. Hence, the improved resistance of the ndh and adhB mutants to H2O2 resulted from their elevated catalase activity. The interrelation between these mutations, the catabolic redox balance, catalase activity, and oxidative stress defense in Z. mobilis is discussed.
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Enhancing Secretion of Endoglucanase in Zymomonas mobilis by Disturbing Peptidoglycan Synthesis. Appl Environ Microbiol 2021; 88:e0216121. [PMID: 34818110 DOI: 10.1128/aem.02161-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Zymomonas mobilis (Z. mobilis) is a potential candidate for consolidated bioprocessing (CBP) strain in lignocellulosic biorefinery. However, the low-level secretion of cellulases limits this CBP process, and the mechanism of protein secretion affected by cell wall peptidoglycan is also not well understood. Here we constructed several Penicillin Binding Proteins (PBPs)-deficient strains derivated from Z. mobilis S192 to perturb the cell wall peptidoglycan network and investigated the effects of peptidoglycan on the endoglucanase secretion. Results showed that extracellular recombinant endoglucanase production was significantly enhanced in PBPs mutant strains, notably, △1089/0959 (4.09-fold) and △0959 (5.76-fold) in comparison to parent strains. Besides, for PBPs-deficient strains, the growth performance was not significantly inhibited but with enhanced antibiotic sensitivity and reduced inhibitor tolerance, otherwise, cell morphology was altered obviously. The concentration of intracellular soluble peptidoglycan was increased, especially for single gene deletion. Outer membrane permeability of PBPs-deficient strains was also improved, notably, △1089/0959 (1.14-fold) and △0959 (1.07-fold), which might explain the increased endoglucanase extracellular secretion. Our finding indicated that PBPs-deficient Z. mobilis is capable of increasing endoglucanase extracellular secretion via cell wall peptidoglycan disturbance and it will provide a foundation for the development of CBP technology in Z. mobilis in the future. IMPORTANCE Cell wall peptidoglycan has the function to maintain cell robustness, and also acts as the barrier to secret recombinant proteins from the cytoplasm to extracellular space in Z. mobilis and other bacterias. Herein, we perturb the peptidoglycan synthesis network via knocking out PBPs (ZMO0197, ZMO0959, ZMO1089) in order to enhance recombinant endoglycanase extracellular secretion in Z. mobilis S912. This study can not only lay the foundation for understanding the regulatory network of cell wall synthesis but also provide guidance for the construction of CBP strains in Z. mobilis.
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Zhu W, Shi X, Qi Y, Wang X, Chang L, Zhao C, Zhu L, Jiang J. Commensal microbiota and host metabolic divergence are associated with the adaptation of Diploderma vela to spatially heterogeneous environments. Integr Zool 2021; 17:346-365. [PMID: 34520122 DOI: 10.1111/1749-4877.12590] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/03/2021] [Accepted: 09/06/2021] [Indexed: 01/04/2023]
Abstract
Heterogeneous environment adaptation is critical to understand the species evolution and response to climate change. However, how narrow-range species adapt to micro-geographic heterogeneity has been overlooked, and there is a lack of insights from metabolism and commensal microbiota. Here, we studied the environmental adaptation for 3 geographic populations (>40 km apart) of Diploderma vela, a lizard endemic to dry-hot valleys of the Hengduan Mountain Region. The climatic boundary caused a cooler, droughtier, and barren environment for northernmost population (RM) than the middle (QZK) and southernmost populations (FS). Correspondingly, significant divergences in liver and muscle metabolism and commensal microbiota were detected between RM and QZK or FS individuals, but not between QZK and FS individuals. Phospholipid composition, coenzyme level (i.e. pyridoxal and NAD+ ), and cholesterol metabolism (e.g. androgen and estriol synthesis) constituted the major metabolic difference between RM and QZK/FS groups. FS and QZK individuals kept abundant Proteobacteria and antifungal strains, while RM individuals maintained more Firmicutes and Bacteroidota. Strong associations existed between varied host metabolite and gut microbes. How were these interpopulation variations associated to the environment adaptation were discussed. These results provided some novel insights into the environmental adaptation and implicated the consequence of climate change on narrow-range species.
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Affiliation(s)
- Wei Zhu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu, China
| | - Xiudong Shi
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yin Qi
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu, China.,Mangkang Ecological Station, Tibet Ecological Safety Monitor Network, Chengdu, China
| | - Xiaoyi Wang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Liming Chang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Chunlin Zhao
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu, China
| | - Lifeng Zhu
- College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Jianping Jiang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chengdu, China.,Mangkang Ecological Station, Tibet Ecological Safety Monitor Network, Chengdu, China
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The Ethanologenic Bacterium Zymomonas mobilis Divides Asymmetrically and Exhibits Heterogeneity in DNA Content. Appl Environ Microbiol 2021; 87:AEM.02441-20. [PMID: 33452021 DOI: 10.1128/aem.02441-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/23/2020] [Indexed: 02/04/2023] Open
Abstract
The alphaproteobacterium Zymomonas mobilis exhibits extreme ethanologenic physiology, making this species a promising biofuel producer. Numerous studies have investigated its biology relevant to industrial applications and mostly at the population level. However, the organization of single cells in this industrially important polyploid species has been largely uncharacterized. In the present study, we characterized basic cellular behavior of Z. mobilis strain Zm6 under anaerobic conditions at the single-cell level. We observed that growing Z. mobilis cells often divided at a nonmidcell position, which contributed to variant cell size at birth. However, the cell size variance was regulated by a modulation of cell cycle span, mediated by a correlation of bacterial tubulin homologue FtsZ ring accumulation with cell growth. The Z. mobilis culture also exhibited heterogeneous cellular DNA content among individual cells, which might have been caused by asynchronous replication of chromosome that was not coordinated with cell growth. Furthermore, slightly angled divisions might have resulted in temporary curvatures of attached Z. mobilis cells. Overall, the present study uncovers a novel bacterial cell organization in Z. mobilis IMPORTANCE With increasing environmental concerns about the use of fossil fuels, development of a sustainable biofuel production platform has been attracting significant public attention. Ethanologenic Z. mobilis species are endowed with an efficient ethanol fermentation capacity that surpasses, in several respects, that of baker's yeast (Saccharomyces cerevisiae), the most-used microorganism for ethanol production. For development of a Z. mobilis culture-based biorefinery, an investigation of its uncharacterized cell biology is important, because bacterial cellular organization and metabolism are closely associated with each other in a single cell compartment. In addition, the current work demonstrates that the polyploid bacterium Z. mobilis exhibits a distinctive mode of bacterial cell organization, likely reflecting its unique metabolism that does not prioritize incorporation of nutrients for cell growth. Thus, another significant result of this work is to advance our general understanding in the diversity of bacterial cell architecture.
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Liu CG, Cao LY, Wen Y, Li K, Mehmood MA, Zhao XQ, Bai FW. Intracellular redox manipulation of Zymomonas mobilis for improving tolerance against lignocellulose hydrolysate-derived stress. Chem Eng Sci 2020. [DOI: 10.1016/j.ces.2020.115933] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Fuchino K, Bruheim P. Increased salt tolerance in Zymomonas mobilis strain generated by adaptative evolution. Microb Cell Fact 2020; 19:147. [PMID: 32690090 PMCID: PMC7372843 DOI: 10.1186/s12934-020-01406-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 07/13/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Ethanologenic alphaproteobacterium Zymomonas mobilis has been acknowledged as a promising biofuel producer. There have been numerous efforts to engineer this species applicable for an industrial-scale bioethanol production. Although Z. mobilis is robustly resilient to certain abiotic stress such as ethanol, the species is known to be sensitive to saline stress at a mild concentration, which hampers its industrial use as an efficient biocatalyst. To overcome this issue, we implemented a laboratory adaptive evolution approach to obtain salt tolerant Z. mobilis strain. RESULTS During an adaptive evolution, we biased selection by cell morphology to exclude stressed cells. The evolved strains significantly improved growth and ethanol production in the medium supplemented with 0.225 M NaCl. Furthermore, comparative metabolomics revealed that the evolved strains did not accumulate prototypical osmolytes, such as proline, to counter the stress during their growth. The sequenced genomes of the studied strains suggest that the disruption of ZZ6_1149 encoding carboxyl-terminal protease was likely responsible for the improved phenotype. CONCLUSIONS The present work successfully generated strains able to grow and ferment glucose under the saline condition that severely perturbs parental strain physiology. Our approach to generate strains, cell shape-based diagnosis and selection, might be applicable to other kinds of strain engineering in Z. mobilis.
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Affiliation(s)
- Katsuya Fuchino
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway.
| | - Per Bruheim
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway
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Todhanakasem T, Wu B, Simeon S. Perspectives and new directions for bioprocess optimization using Zymomonas mobilis in the ethanol production. World J Microbiol Biotechnol 2020; 36:112. [PMID: 32656581 DOI: 10.1007/s11274-020-02885-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 06/29/2020] [Indexed: 12/28/2022]
Abstract
Zymomonas mobilis is an ethanologenic microbe that has a demonstrated potential for use in lignocellulosic biorefineries for bioethanol production. Z. mobilis exhibits a number of desirable characteristics for use as an ethanologenic microbe, with capabilities for metabolic engineering and bioprocess modification. Many advanced genetic tools, including mutation techniques, screening methods and genome editing have been successively performed to improve various Z. mobilis strains as potential consolidated ethanologenic microbes. Many bioprocess strategies have also been applied to this organism for bioethanol production. Z. mobilis biofilm reactors have been modified with various benefits, including high bacterial populations, less fermentation times, high productivity, high cell stability, resistance to the high concentration of substrates and toxicity, and higher product recovery. We suggest that Z. mobilis biofilm reactors could be used in bioethanol production using lignocellulosic substrates under batch, continuous and repeated batch processes.
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Affiliation(s)
- Tatsaporn Todhanakasem
- Department of Agro- Industry, Faculty of Biotechnology, Assumption University, Ramkhamhaeng Road, Bangkapi, Bangkok, 10240, Thailand.
| | - Bo Wu
- Biomass Energy Technology Research Center, Biogas Institute of Ministry of Agriculture and Rural Affairs, Renmin Rd. S 4-13, Chengdu, 610041, China
| | - Saw Simeon
- Absolute Clean Energy Public Company Limited, ITF Tower 7th Floor, Silom Road, Bang Rak, Bangkok, 10500, Thailand
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Metabolic Profiling of Glucose-Fed Metabolically Active Resting Zymomonas mobilis Strains. Metabolites 2020; 10:metabo10030081. [PMID: 32110884 PMCID: PMC7142471 DOI: 10.3390/metabo10030081] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/17/2020] [Accepted: 02/24/2020] [Indexed: 11/17/2022] Open
Abstract
Zymomonas mobilis is the most efficient bacterial ethanol producer and its physiology is potentially applicable to industrial-scale bioethanol production. However, compared to other industrially important microorganisms, the Z. mobilis metabolome and adaptation to various nutritional and genetic perturbations have been poorly characterized. For rational metabolic engineering, it is essential to understand how central metabolism and intracellular redox balance are maintained in Z. mobilis under various conditions. In this study, we applied quantitative mass spectrometry-based metabolomics to explore how glucose-fed non-growing Z. mobilis Zm6 cells metabolically adapt to change of oxygen availability. Mutants partially impaired in ethanol synthesis (Zm6 adhB) or oxidative stress response (Zm6 cat) were also examined. Distinct patterns of adaptation of central metabolite pools due to the change in cultivation condition and between the mutants and Zm6 reference strain were observed. Decreased NADH/NAD ratio under aerobic incubation corresponded to higher concentrations of the phosphorylated glycolytic intermediates, in accordance with predictions of the kinetic model of Entner–Doudoroff pathway. The effects on the metabolite pools of aerobic to anaerobic transition were similar in the mutants, yet less pronounced. The present data on metabolic plasticity of non-growing Z. mobilis cells will facilitate the further metabolic engineering of the respective strains and their application as biocatalysts.
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Zymomonas mobilis metabolism: Novel tools and targets for its rational engineering. Adv Microb Physiol 2020; 77:37-88. [PMID: 34756211 DOI: 10.1016/bs.ampbs.2020.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Zymomonas mobilis is an α-proteobacterium that interests the biofuel industry due to its perfect ethanol fermentation yields. From its first description as a bacterial isolate in fermented alcoholic beverages to date, Z. mobilis has been rigorously studied in directions basic and applied. The Z. mobilis powerful Entner-Doudoroff glycolytic pathway has been the center of rigorous biochemical studies and, aside from ethanol, it has attracted interest in terms of high-added-value chemical manufacturing. Energetic balances and the effects of respiration have been explored in fundamental directions as also in applications pursuing strain enhancement and the utilization of alternative carbon sources. Metabolic modeling has addressed the optimization of the biochemical circuitry at various conditions of growth and/or substrate utilization; it has been also critical in predicting desirable end-product yields via flux redirection. Lastly, stress tolerance has received particular attention, since it directly determines biocatalytical performance at challenging bioreactor conditions. At a genetic level, advances in the genetic engineering of the organism have brought forth beneficial manipulations in the Z. mobilis gene pool, e.g., knock-outs, knock-ins and gene stacking, aiming to broaden the metabolic repertoire and increase robustness. Recent omic and expressional studies shed light on the genomic content of the most applied strains and reveal landscapes of activity manifested at ambient or reactor-based conditions. Studies such as those reviewed in this work, contribute to the understanding of the biology of Z. mobilis, enable insightful strain development, and pave the way for the transformation of Z. mobilis into a consummate organism for biomass conversion.
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Kalnenieks U, Balodite E, Rutkis R. Metabolic Engineering of Bacterial Respiration: High vs. Low P/O and the Case of Zymomonas mobilis. Front Bioeng Biotechnol 2019; 7:327. [PMID: 31781557 PMCID: PMC6861446 DOI: 10.3389/fbioe.2019.00327] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 10/28/2019] [Indexed: 11/13/2022] Open
Abstract
Respiratory chain plays a pivotal role in the energy and redox balance of aerobic bacteria. By engineering respiration, it is possible to alter the efficiency of energy generation and intracellular redox state, and thus affect the key bioprocess parameters: cell yield, productivity and stress resistance. Here we summarize the current metabolic engineering and synthetic biology approaches to bacterial respiratory metabolism, with a special focus on the respiratory chain of the ethanologenic bacterium Zymomonas mobilis. Electron transport in Z. mobilis can serve as a model system of bacterial respiration with low oxidative phosphorylation efficiency. Its application for redox balancing and relevance for improvement of stress tolerance are analyzed.
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Affiliation(s)
- Uldis Kalnenieks
- Institute of Microbiology and Biotechnology, University of Latvia, Riga, Latvia
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Roles of d-Lactate Dehydrogenases in the Anaerobic Growth of Shewanella oneidensis MR-1 on Sugars. Appl Environ Microbiol 2019; 85:AEM.02668-18. [PMID: 30504209 DOI: 10.1128/aem.02668-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 11/18/2018] [Indexed: 11/20/2022] Open
Abstract
Shewanella oneidensis MR-1 is a facultative anaerobe that respires using a variety of electron acceptors. Although this organism is incapable of fermentative growth in the absence of electron acceptors, its genome encodes LdhA (a putative fermentative NADH-dependent d-lactate dehydrogenase [d-LDH]) and Dld (a respiratory quinone-dependent d-LDH). However, the physiological roles of LdhA in MR-1 are unclear. Here, we examined the activity, transcriptional regulation, and traits of deletion mutants to gain insight into the roles of LdhA in the anaerobic growth of MR-1. Analyses of d-LDH activity in MR-1 and the ldhA deletion mutant confirmed that LdhA functions as an NADH-dependent d-LDH that catalyzes the reduction of pyruvate to d-lactate. In vivo and in vitro assays revealed that ldhA expression was positively regulated by the cyclic-AMP receptor protein, a global transcription factor that regulates anaerobic respiratory pathways in MR-1, suggesting that LdhA functions in coordination with anaerobic respiration. Notably, we found that a deletion mutant of all four NADH dehydrogenases (NDHs) in MR-1 (ΔNDH mutant) retained the ability to grow on N-acetylglucosamine under fumarate-respiring conditions, while an additional deletion of ldhA or dld deprived the ΔNDH mutant of this growth ability. These results indicate that LdhA-Dld serves as a bypass of NDH in electron transfer from NADH to quinones. Our findings suggest that the LdhA-Dld system manages intracellular redox balance by utilizing d-lactate as a temporal electron sink under electron acceptor-limited conditions.IMPORTANCE NADH-dependent LDHs are conserved among diverse organisms and contribute to NAD+ regeneration in lactic acid fermentation. However, this type of LDH is also present in nonfermentative bacteria, including members of the genus Shewanella, while their physiological roles in these bacteria remain unknown. Here, we show that LdhA (an NADH-dependent d-LDH) works in concert with Dld (a quinone-dependent d-LDH) to transfer electrons from NADH to quinones during sugar catabolism in S. oneidensis MR-1. Our results indicate that d-lactate acts as an intracellular electron mediator to transfer electrons from NADH to membrane quinones. In addition, d-lactate serves as a temporal electron sink when respiratory electron acceptors are not available. Our study suggests novel physiological roles for d-LDHs in providing nonfermentative bacteria with catabolic flexibility under electron acceptor-limited conditions.
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Zhang K, Lu X, Li Y, Jiang X, Liu L, Wang H. New technologies provide more metabolic engineering strategies for bioethanol production in Zymomonas mobilis. Appl Microbiol Biotechnol 2019; 103:2087-2099. [PMID: 30661108 DOI: 10.1007/s00253-019-09620-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/02/2019] [Accepted: 01/03/2019] [Indexed: 02/06/2023]
Abstract
Bioethanol has been considered as a potentially renewable energy source, and metabolic engineering plays an important role in the production of biofuels. As an efficient ethanol-producing bacterium, Zymomonas mobilis has garnered special attention due to its high sugar uptake, ethanol yield, and tolerance. Different metabolic engineering strategies have been used to establish new metabolic pathways for Z. mobilis to broaden its substrate range, remove competing pathways, and enhance its tolerance to ethanol and lignocellulosic hydrolysate inhibitors. Recent advances in omics technology, computational modeling and simulation, system biology, and synthetic biology contribute to the efficient re-design and manipulation of microbes via metabolic engineering at the whole-cell level. In this review, we summarize the progress of some new technologies used for metabolic engineering to improve bioethanol production and tolerance in Z. mobilis. Some successful examples of metabolic engineering used to develop strains for ethanol production are described in detail. Lastly, some important strategies for future metabolic engineering efforts are also highlighted.
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Affiliation(s)
- Kun Zhang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Xinxin Lu
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Yi Li
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Xiaobing Jiang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Lei Liu
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China
| | - Hailei Wang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, Henan, China.
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Wu B, Qin H, Yang Y, Duan G, Yang S, Xin F, Zhao C, Shao H, Wang Y, Zhu Q, Tan F, Hu G, He M. Engineered Zymomonas mobilis tolerant to acetic acid and low pH via multiplex atmospheric and room temperature plasma mutagenesis. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:10. [PMID: 30627218 PMCID: PMC6321654 DOI: 10.1186/s13068-018-1348-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 12/24/2018] [Indexed: 05/19/2023]
Abstract
BACKGROUND Cellulosic biofuels are sustainable compared to fossil fuels. However, inhibitors, such as acetic acid generated during lignocellulose pretreatment and hydrolysis, would significantly inhibit microbial fermentation efficiency. Microbial mutants able to tolerate high concentration of acetic acid are needed urgently to alleviate this inhibition. RESULTS Zymomonas mobilis mutants AQ8-1 and AC8-9 with enhanced tolerance against acetic acid were generated via a multiplex atmospheric and room temperature plasma (mARTP) mutagenesis. The growth and ethanol productivity of AQ8-1 and AC8-9 were both improved in the presence of 5.0-8.0 g/L acetic acid. Ethanol yield reached 84% of theoretical value in the presence of 8.0 g/L acetic acid (~ pH 4.0). Furthermore, a mutant tolerant to pH 3.5, named PH1-29, was generated via the third round of ARTP mutagenesis. PH1-29 showed enhanced growth and ethanol production under both sterilized/unsterilized conditions at pH 4.0 or 3.5. Intracellular NAD levels revealed that mARTP mutants could modulate NADH/NAD+ ratio to respond to acetic acid and low pH stresses. Moreover, genomic re-sequencing revealed that eleven single nucleic variations (SNVs) were likely related to acetic acid and low pH tolerance. Most SNVs were targeted in regions between genes ZMO0952 and ZMO0956, ZMO0152 and ZMO0153, and ZMO0373 and ZMO0374. CONCLUSIONS The multiplex mutagenesis strategy mARTP was efficient for enhancing the tolerance in Z. mobilis. The ARTP mutants generated in this study could serve as potential cellulosic ethanol producers.
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Affiliation(s)
- Bo Wu
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Han Qin
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Yiwei Yang
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Guowei Duan
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Shihui Yang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan, 430062 China
| | - Fengxue Xin
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 Puzhu Rd, Pukou District, Nanjing, 211816 China
| | - Chunyan Zhao
- College of Life Science, Sichuan Normal University, Section 2-1819, Chenglong Avenue, Chengdu, 610101 China
| | - Huanhuan Shao
- College of Life Science, Sichuan Normal University, Section 2-1819, Chenglong Avenue, Chengdu, 610101 China
| | - Yanwei Wang
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Qili Zhu
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Furong Tan
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Guoquan Hu
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Mingxiong He
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
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15
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Zhang L, Bao W, Wei R, Fu S, Gong H. Inactivating NADH:quinone oxidoreductases affects the growth and metabolism of Klebsiella pneumoniae. Biotechnol Appl Biochem 2018; 65:857-864. [PMID: 30063071 DOI: 10.1002/bab.1684] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 07/22/2018] [Indexed: 11/10/2022]
Abstract
NADH:quinone oxidoreductases (NQOs) act as the electron entry sites in bacterial respiration and oxidize intracellular NADH that is essential for the synthesis of numerous molecules. Klebsiella pneumoniae contains three NQOs (NDH-1, NDH-2, and NQR). The effects of inactivating these NQOs, separately and together, on cell metabolism were investigated under different culture conditions. Defective growth was evident in NDH-1-NDH-2 double and NDH-1-NDH-2-NQR triple deficient mutants, which was probably due to damage to the respiratory chain. The results also showed that K. pneumoniae can flexibly use NQOs to maintain normal growth in single NQO-deficient mutants. And more interestingly, under aerobic conditions, inactivating NDH-1 resulted in a high intracellular NADH:NAD+ ratio, which was proven to be beneficial for 2,3-butanediol production. Compared with the parent strain, 2,3-butanediol production by the NDH-1-deficient mutant was increased by 46% and 62% in glycerol- and glucose-based media, respectively. Thus, our findings provide a practical strategy for metabolic engineering of respiratory chains to promote the biosynthesis of 2,3-butanediol in K. pneumoniae.
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Affiliation(s)
- Lijuan Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Wenjing Bao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Renquan Wei
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Shuilin Fu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
| | - Heng Gong
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, People's Republic of China
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16
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Wang X, He Q, Yang Y, Wang J, Haning K, Hu Y, Wu B, He M, Zhang Y, Bao J, Contreras LM, Yang S. Advances and prospects in metabolic engineering of Zymomonas mobilis. Metab Eng 2018; 50:57-73. [PMID: 29627506 DOI: 10.1016/j.ymben.2018.04.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/31/2018] [Accepted: 04/01/2018] [Indexed: 12/22/2022]
Abstract
Biorefinery of biomass-based biofuels and biochemicals by microorganisms is a competitive alternative of traditional petroleum refineries. Zymomonas mobilis is a natural ethanologen with many desirable characteristics, which makes it an ideal industrial microbial biocatalyst for commercial production of desirable bioproducts through metabolic engineering. In this review, we summarize the metabolic engineering progress achieved in Z. mobilis to expand its substrate and product ranges as well as to enhance its robustness against stressful conditions such as inhibitory compounds within the lignocellulosic hydrolysates and slurries. We also discuss a few metabolic engineering strategies that can be applied in Z. mobilis to further develop it as a robust workhorse for economic lignocellulosic bioproducts. In addition, we briefly review the progress of metabolic engineering in Z. mobilis related to the classical synthetic biology cycle of "Design-Build-Test-Learn", as well as the progress and potential to develop Z. mobilis as a model chassis for biorefinery practices in the synthetic biology era.
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Affiliation(s)
- Xia Wang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan 430062, China.
| | - Qiaoning He
- Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan 430062, China.
| | - Yongfu Yang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan 430062, China.
| | - Jingwen Wang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan 430062, China.
| | - Katie Haning
- Institute for Cellular and Molecular Biology, Department of Chemical Engineering, Cockrell School of Engineering, University of Texas at Austin, Austin, TX, United States.
| | - Yun Hu
- Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan 430062, China.
| | - Bo Wu
- Key Laboratory of Development and Application of Rural Renewable Energy, Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, South Renmin Road, Chengdu 610041, China.
| | - Mingxiong He
- Key Laboratory of Development and Application of Rural Renewable Energy, Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, South Renmin Road, Chengdu 610041, China.
| | - Yaoping Zhang
- DOE-Great Lakes Bioenergy Research Center (GLBRC), University of Wisconsin-Madison, Madison, WI, United States.
| | - Jie Bao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
| | - Lydia M Contreras
- Institute for Cellular and Molecular Biology, Department of Chemical Engineering, Cockrell School of Engineering, University of Texas at Austin, Austin, TX, United States.
| | - Shihui Yang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan 430062, China.
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17
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Hirose A, Kasai T, Aoki M, Umemura T, Watanabe K, Kouzuma A. Electrochemically active bacteria sense electrode potentials for regulating catabolic pathways. Nat Commun 2018; 9:1083. [PMID: 29540717 PMCID: PMC5852097 DOI: 10.1038/s41467-018-03416-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 02/09/2018] [Indexed: 01/08/2023] Open
Abstract
Electrochemically active bacteria (EAB) receive considerable attention for their utility in bioelectrochemical processes. Although electrode potentials are known to affect the metabolic activity of EAB, it is unclear whether EAB are able to sense and respond to electrode potentials. Here, we show that, in the presence of a high-potential electrode, a model EAB Shewanella oneidensis MR-1 can utilize NADH-dependent catabolic pathways and a background formate-dependent pathway to achieve high growth yield. We also show that an Arc regulatory system is involved in sensing electrode potentials and regulating the expression of catabolic genes, including those for NADH dehydrogenase. We suggest that these findings may facilitate the use of EAB in biotechnological processes and offer the molecular bases for their ecological strategies in natural habitats.
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Affiliation(s)
- Atsumi Hirose
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Takuya Kasai
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Motohide Aoki
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Tomonari Umemura
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Kazuya Watanabe
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Atsushi Kouzuma
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan.
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18
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Yang Y, Hu M, Tang Y, Geng B, Qiu M, He Q, Chen S, Wang X, Yang S. Progress and perspective on lignocellulosic hydrolysate inhibitor tolerance improvement in Zymomonas mobilis. BIORESOUR BIOPROCESS 2018. [DOI: 10.1186/s40643-018-0193-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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19
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Ai Z, Lv X, Huang S, Liu G, Sun X, Chen H, Sun J, Feng Z. The effect of controlled and uncontrolled pH cultures on the growth of Lactobacillus delbrueckii subsp. bulgaricus. Lebensm Wiss Technol 2017. [DOI: 10.1016/j.lwt.2016.11.057] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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20
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Wang JL, Wu B, Qin H, You Y, Liu S, Shui ZX, Tan FR, Wang YW, Zhu QL, Li YB, Ruan ZY, Ma KD, Dai LC, Hu GQ, He MX. Engineered Zymomonas mobilis for salt tolerance using EZ-Tn5-based transposon insertion mutagenesis system. Microb Cell Fact 2016; 15:101. [PMID: 27287016 PMCID: PMC4901475 DOI: 10.1186/s12934-016-0503-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/01/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The cell growth and ethanol yield of Zymomonas mobilis may be detrimentally affected by salt stress frequently present in some biomass-based fermentation systems, leading to a decrease in the rate of sugar conversion to ethanol or other bioproducts. To address this problem, improving the salt tolerance of Z. mobilis is a desirable way. However, limited progress has been made in development of Z. mobilis with higher salt tolerance for some technical challenges in the past decades. Recently, transposon insertion mutant system has been widely used as a novel genetic tool in many organisms to develop mutant strains. In this study, Tn5-based transposon insertion mutagenesis system firstly used for construction of higher salt tolerance strain in Z. mobilis. RESULTS Approximately 200 Z. mobilis ZM4 mutants were generated by using Tn5-based transposon mutagenesis system. The mutant strain ZMT2 with improved salt tolerance phenotype was obtained by screening on RM agar plates with additional 1 % NaCl. Strain ZMT2 was confirmed to exhibit better fermentation performance under NaCl stress than wild type of strain ZM4. The transposon insertion was located in ZMO1122 (himA) by genome walking. Discruption of himA gene showed that himA may play an important role in response to salt tolerance in Z. mobils. CONCLUSIONS The mutant strain ZMT2 with a transposon insertion in himA gene of the genome showed obviously higher sugar conversion rate to ethonal under up to 2 % NaCl stress than did the wild ZM4 strain. Besides, ZMT2 exhibited shared fermentative capabilities with wild ZM4 strain under no or low NaCl stress. This report firstly showed that himA played a role in responding to NaCl stress. Furthermore, the result indicated that Tn5-based transposon mutagenesis system was a feasible tool not only for genetic engineering in Z. mobilis strain improvement, but also in tapping resistent genes.
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Affiliation(s)
- Jing-Li Wang
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Bo Wu
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Han Qin
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Yang You
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Song Liu
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Zong-Xia Shui
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Fu-Rong Tan
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Yan-Wei Wang
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Qi-Li Zhu
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Yan-Bin Li
- Xinjiang Production and Construction Corps Key Laboratory of Protection and Utilization of Biological Resources, College of Life Sciences, Tarim University, Tarim Basin, Alaer City, 843300, People's Republic of China
| | - Zhi-Yong Ruan
- Key Laboratory of Microbial Resources (Ministry of Agriculture, China), Institute of Agricultural Resources and Regional Planning, CAAS, Beijing, 100081, People's Republic of China
| | - Ke-Dong Ma
- College of Environmental and Chemical Engineering, Dalian University, Dalian, 116622, People's Republic of China
| | - Li-Chun Dai
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Guo-Quan Hu
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China
| | - Ming-Xiong He
- Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nanlu, Chengdu, 610041, People's Republic of China.
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21
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Rutkis R, Strazdina I, Balodite E, Lasa Z, Galinina N, Kalnenieks U. The Low Energy-Coupling Respiration in Zymomonas mobilis Accelerates Flux in the Entner-Doudoroff Pathway. PLoS One 2016; 11:e0153866. [PMID: 27100889 PMCID: PMC4839697 DOI: 10.1371/journal.pone.0153866] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 04/05/2016] [Indexed: 11/18/2022] Open
Abstract
Performing oxidative phosphorylation is the primary role of respiratory chain both in bacteria and eukaryotes. Yet, the branched respiratory chains of prokaryotes contain alternative, low energy-coupling electron pathways, which serve for functions other than oxidative ATP generation (like those of respiratory protection, adaptation to low-oxygen media, redox balancing, etc.), some of which are still poorly understood. We here demonstrate that withdrawal of reducing equivalents by the energetically uncoupled respiratory chain of the bacterium Zymomonas mobilis accelerates its fermentative catabolism, increasing the glucose consumption rate. This is in contrast to what has been observed in other respiring bacteria and yeast. This effect takes place after air is introduced to glucose-consuming anaerobic cell suspension, and can be simulated using a kinetic model of the Entner-Doudoroff pathway in combination with a simple net reaction of NADH oxidation that does not involve oxidative phosphorylation. Although aeration hampers batch growth of respiring Z. mobilis culture due to accumulation of toxic byproducts, nevertheless under non-growing conditions respiration is shown to confer an adaptive advantage for the wild type over the non-respiring Ndh knock-out mutant. If cells get occasional access to limited amount of glucose for short periods of time, the elevated glucose uptake rate selectively improves survival of the respiring Z. mobilis phenotype.
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Affiliation(s)
- Reinis Rutkis
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia
| | - Inese Strazdina
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia
| | - Elina Balodite
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia
| | - Zane Lasa
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia
| | - Nina Galinina
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia
| | - Uldis Kalnenieks
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Street 1, Riga, LV-1004, Latvia
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22
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Yang S, Mohagheghi A, Franden MA, Chou YC, Chen X, Dowe N, Himmel ME, Zhang M. Metabolic engineering of Zymomonas mobilis for 2,3-butanediol production from lignocellulosic biomass sugars. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:189. [PMID: 27594916 PMCID: PMC5010730 DOI: 10.1186/s13068-016-0606-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 08/26/2016] [Indexed: 05/18/2023]
Abstract
BACKGROUND To develop pathways for advanced biofuel production, and to understand the impact of host metabolism and environmental conditions on heterologous pathway engineering for economic advanced biofuels production from biomass, we seek to redirect the carbon flow of the model ethanologen Zymomonas mobilis to produce desirable hydrocarbon intermediate 2,3-butanediol (2,3-BDO). 2,3-BDO is a bulk chemical building block, and can be upgraded in high yields to gasoline, diesel, and jet fuel. RESULTS 2,3-BDO biosynthesis pathways from various bacterial species were examined, which include three genes encoding acetolactate synthase, acetolactate decarboxylase, and butanediol dehydrogenase. Bioinformatics analysis was carried out to pinpoint potential bottlenecks for high 2,3-BDO production. Different combinations of 2,3-BDO biosynthesis metabolic pathways using genes from different bacterial species have been constructed. Our results demonstrated that carbon flux can be deviated from ethanol production into 2,3-BDO biosynthesis, and all three heterologous genes are essential to efficiently redirect pyruvate from ethanol production for high 2,3-BDO production in Z. mobilis. The down-selection of best gene combinations up to now enabled Z. mobilis to reach the 2,3-BDO production of more than 10 g/L from glucose and xylose, as well as mixed C6/C5 sugar streams derived from the deacetylation and mechanical refining process. CONCLUSIONS This study confirms the value of integrating bioinformatics analysis and systems biology data during metabolic engineering endeavors, provides guidance for value-added chemical production in Z. mobilis, and reveals the interactions between host metabolism, oxygen levels, and a heterologous 2,3-BDO biosynthesis pathway. Taken together, this work provides guidance for future metabolic engineering efforts aimed at boosting 2,3-BDO titer anaerobically.
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Affiliation(s)
- Shihui Yang
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, 80401 USA
- Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan, 430062 China
| | - Ali Mohagheghi
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, 80401 USA
| | - Mary Ann Franden
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, 80401 USA
| | - Yat-Chen Chou
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, 80401 USA
| | - Xiaowen Chen
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, 80401 USA
| | - Nancy Dowe
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, 80401 USA
| | - Michael E. Himmel
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Min Zhang
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, 80401 USA
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