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Nawab S, Zhang Y, Ullah MW, Lodhi AF, Shah SB, Rahman MU, Yong YC. Microbial host engineering for sustainable isobutanol production from renewable resources. Appl Microbiol Biotechnol 2024; 108:33. [PMID: 38175234 DOI: 10.1007/s00253-023-12821-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 12/10/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024]
Abstract
Due to the limited resources and environmental problems associated with fossil fuels, there is a growing interest in utilizing renewable resources for the production of biofuels through microbial fermentation. Isobutanol is a promising biofuel that could potentially replace gasoline. However, its production efficiency is currently limited by the use of naturally isolated microorganisms. These naturally isolated microorganisms often encounter problems such as a limited range of substrates, low tolerance to solvents or inhibitors, feedback inhibition, and an imbalanced redox state. This makes it difficult to improve their production efficiency through traditional process optimization methods. Fortunately, recent advancements in genetic engineering technologies have made it possible to enhance microbial hosts for the increased production of isobutanol from renewable resources. This review provides a summary of the strategies and synthetic biology approaches that have been employed in the past few years to improve naturally isolated or non-natural microbial hosts for the enhanced production of isobutanol by utilizing different renewable resources. Furthermore, it also discusses the challenges that are faced by engineered microbial hosts and presents future perspectives to enhancing isobutanol production. KEY POINTS: • Promising potential of isobutanol to replace gasoline • Engineering of native and non-native microbial host for isobutanol production • Challenges and opportunities for enhanced isobutanol production.
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Affiliation(s)
- Said Nawab
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - YaFei Zhang
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Muhammad Wajid Ullah
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Adil Farooq Lodhi
- Department of Microbiology, Faculty of Biological and Health Sciences, Hazara University, Mansehra, Pakistan
| | - Syed Bilal Shah
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Mujeeb Ur Rahman
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Yang-Chun Yong
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China.
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Wang J, Kasuga T, Fan Z. Cellobionate production from sodium hydroxide pretreated wheat straw by engineered Neurospora crassa HL10. Bioprocess Biosyst Eng 2024:10.1007/s00449-024-03061-w. [PMID: 38995362 DOI: 10.1007/s00449-024-03061-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 07/03/2024] [Indexed: 07/13/2024]
Abstract
This study investigated cellobionate production from a lignocellulosic substrate using Neurospora crassa HL10. Utilizing NaOH-pretreated wheat straw as the substrate obviated the need for an exogenous redox mediator addition, as lignin contained in the pretreated wheat served as a natural mediator. The low laccase production by N. crassa HL10 on pretreated wheat straw caused slow cellobionate production, and exogenous laccase addition accelerated the process. Cycloheximide induced substantial laccase production in N. crassa HL10, enabling the strain to yield approximately 57 mM cellobionate from pretreated wheat straw (equivalent to 20 g/L cellulose), shortening the conversion time from 8 to 6 days. About 92% of the cellulose contained in the pretreated wheat straw is converted to cellobionate. In contrast to existing methods requiring pure cellobiose or cellulase enzymes, this process efficiently converts a low-cost feedstock into cellobionate at a high yield without enzyme or redox mediator supplementation.
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Affiliation(s)
- Jiajie Wang
- Department of Biological and Agricultural Engineering, University of California , Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Takao Kasuga
- Department of Plant Pathology, University of California , Davis, One Shields Avenue, Davis, CA, 95616, USA
- United States Department of Agriculture-Agricultural Research Service, University of California, Davis, CA, 95616, USA
| | - Zhiliang Fan
- Department of Biological and Agricultural Engineering, University of California , Davis, One Shields Avenue, Davis, CA, 95616, USA.
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Gu P, Li F, Huang Z. Engineering Escherichia coli for Isobutanol Production from Xylose or Glucose-Xylose Mixture. Microorganisms 2023; 11:2573. [PMID: 37894231 PMCID: PMC10609591 DOI: 10.3390/microorganisms11102573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/11/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023] Open
Abstract
Aiming to overcome the depletion of fossil fuels and serious environmental pollution, biofuels such as isobutanol have garnered increased attention. Among different synthesis methods, the microbial fermentation of isobutanol from raw substrate is a promising strategy due to its low cost and environmentally friendly and optically pure products. As an important component of lignocellulosics and the second most common sugar in nature, xylose has become a promising renewable resource for microbial production. However, bottlenecks in xylose utilization limit its wide application as substrates. In this work, an isobutanol synthetic pathway from xylose was first constructed in E. coli MG1655 through the combination of the Ehrlich and Dahms pathways. The engineering of xylose transport and electron transport chain complexes further improved xylose assimilation and isobutanol production. By optimizing xylose supplement concentration, the recombinant E. coli strain BWL4 could produce 485.35 mg/L isobutanol from 20 g/L of xylose. To our knowledge, this is the first report related to isobutanol production using xylose as a sole carbon source in E. coli. Additionally, a glucose-xylose mixture was utilized as the carbon source. The Entner-Doudorof pathway was used to assimilate glucose, and the Ehrlich pathway was applied for isobutanol production. After carefully engineering the recombinant E. coli, strain BWL9 could produce 528.72 mg/L isobutanol from a mixture of 20 g/L glucose and 10 g/L xylose. The engineering strategies applied in this work provide a useful reference for the microbial production of isobutanol from xylose or glucose-xylose mixture.
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Affiliation(s)
- Pengfei Gu
- School of Biological Science and Technology, University of Jinan, Jinan 250022, China;
| | - Fangfang Li
- Yantai Food and Drug Control and Test Center, Yantai 264003, China;
| | - Zhaosong Huang
- School of Biological Science and Technology, University of Jinan, Jinan 250022, China;
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Gu P, Zhao S, Niu H, Li C, Jiang S, Zhou H, Li Q. Synthesis of isobutanol using acetate as sole carbon source in Escherichia coli. Microb Cell Fact 2023; 22:196. [PMID: 37759284 PMCID: PMC10537434 DOI: 10.1186/s12934-023-02197-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
BACKGROUND With concerns about depletion of fossil fuel and environmental pollution, synthesis of biofuels such as isobutanol from low-cost substrate by microbial cell factories has attracted more and more attention. As one of the most promising carbon sources instead of food resources, acetate can be utilized by versatile microbes and converted into numerous valuable chemicals. RESULTS An isobutanol synthetic pathway using acetate as sole carbon source was constructed in E. coli. Pyruvate was designed to be generated via acetyl-CoA by pyruvate-ferredoxin oxidoreductase YdbK or anaplerotic pathway. Overexpression of transhydrogenase and NAD kinase increased the isobutanol titer of recombinant E. coli from 121.21 mg/L to 131.5 mg/L under batch cultivation. Further optimization of acetate supplement concentration achieved 157.05 mg/L isobutanol accumulation in WY002, representing the highest isobutanol titer by using acetate as sole carbon source. CONCLUSIONS The utilization of acetate as carbon source for microbial production of valuable chemicals such as isobutanol could reduce the consumption of food-based substrates and save production cost. Engineering strategies applied in this study will provide a useful reference for microbial production of pyruvate derived chemical compounds from acetate.
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Affiliation(s)
- Pengfei Gu
- School of Biological Science and Technology, University of Jinan, Jinan, 250022, People's Republic of China.
| | - Shuo Zhao
- School of Biological Science and Technology, University of Jinan, Jinan, 250022, People's Republic of China
| | - Hao Niu
- School of Biological Science and Technology, University of Jinan, Jinan, 250022, People's Republic of China
| | - Chengwei Li
- RZBC GROUP CO., LTD, Rizhao, 276800, Shandong, China
| | | | - Hao Zhou
- RZBC GROUP CO., LTD, Rizhao, 276800, Shandong, China
| | - Qiang Li
- School of Biological Science and Technology, University of Jinan, Jinan, 250022, People's Republic of China
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Bieringer E, García Vázquez U, Klein L, Moretó Bravo N, Tobler M, Weuster-Botz D. Bioproduction and applications of aldobionic acids with a focus on maltobionic and cellobionic acid. Bioprocess Biosyst Eng 2023:10.1007/s00449-023-02872-7. [PMID: 37058246 DOI: 10.1007/s00449-023-02872-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 03/27/2023] [Indexed: 04/15/2023]
Abstract
Aldobionic acids are sugar acids which consist of a disaccharide with an anomeric acid group. The most famous is lactobionic acid (LBA). LBA is used in many applications such as food and beverages, pharmaceuticals and medicine, cosmetics or chemical processes. During the last decade, all these industries are observing a shift of consumer preferences towards plant-based options. Thus, the biotechnological industry is trying to replace the animal-derived LBA. Maltobionic acid (MBA) and cellobionic acid (CBA) are two stereoisomers of LBA which have emerged as vegan alternatives. However, MBA and CBA face different obstacles related to their industrial production. While traditionally used electrochemical or chemical catalysis often rely on cost intensive and/or hazardous catalysts, novel production methods with microorganisms are still poorly studied. In the first part, this paper discusses both alternatives in terms of their characteristics and applications. In the second part, it reviews the long-studied chemical production and the novel bioproduction methods, which are based on enzymatic and microbial systems. This review concludes with a discussion of future work needed to bring their production to the industrial scale.
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Affiliation(s)
- Emmeran Bieringer
- TUM School of Engineering and Design, Department of Energy and Process Engineering, Chair of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany
| | - Uxía García Vázquez
- TUM School of Engineering and Design, Technical University of Munich, Boltzmannstraße 15, 85748, Garching, Germany
| | - Luisa Klein
- TUM School of Engineering and Design, Technical University of Munich, Boltzmannstraße 15, 85748, Garching, Germany
| | - Núria Moretó Bravo
- TUM School of Natural Sciences, Technical University of Munich, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Matthias Tobler
- TUM Campus Straubing for Biotechnology and Sustainability, Technical University of Munich, Petersgasse 5, 94315, Straubing, Germany
| | - Dirk Weuster-Botz
- TUM School of Engineering and Design, Department of Energy and Process Engineering, Chair of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany.
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Efficient production of cellobionic acid using whole-cell biocatalyst of genetically modified Pseudomonas taetrolens. Bioprocess Biosyst Eng 2022; 45:1057-1064. [PMID: 35412074 DOI: 10.1007/s00449-022-02725-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/28/2022] [Indexed: 11/02/2022]
Abstract
Pseudomonas taetrolens has previously been shown to convert cellobiose to cellobionic acid (CBA), which can potentially be used in cosmetics, food, and pharmaceutical industries. The cellobiose-oxidizing activity of the P. taetrolens strain, which expressed the homologous quinoprotein glucose dehydrogenase (GDH), was increased by approximately 50.8% compared to the original strain. Whole-cell biocatalyst (WCB) of the genetically modified P. taetrolens strain [pDSK-GDH] was prepared simply by fermentation and washing processes. Reaction conditions for the proper use of WCB, such as reaction temperature, cell density to be added, and cell harvest time for preparing WCB, were investigated. The highest CBA productivity (18.2 g/L/h) was achieved when WCB prepared in the late-exponential phase of cell culture was used at 35 °C with cell density of 10 at OD600nm. Under these conditions, 200 g/L of cellobiose was all converted to CBA in 11 h, and the WCB of P. taetrolens [pDSK-GDH] maintained the maximum catalytic activity during at least six cycles without a significant decline in the productivity. Our results suggest that the manufacture of WCB based on genetically engineered P. taetrolens and its optimized use could be further developed as an economically viable option for the large-scale production of CBA.
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Lakshmi NM, Binod P, Sindhu R, Awasthi MK, Pandey A. Microbial engineering for the production of isobutanol: current status and future directions. Bioengineered 2021; 12:12308-12321. [PMID: 34927549 PMCID: PMC8809953 DOI: 10.1080/21655979.2021.1978189] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Fermentation-derived alcohols have gained much attention as an alternate fuel due to its minimal effects on atmosphere. Besides its application as biofuel it is also used as raw material for coating resins, deicing fluid, additives in polishes, etc. Among the liquid alcohol type of fuels, isobutanol has more advantage than ethanol. Isobutanol production is reported in native yeast strains, but the production titer is very low which is about 200 mg/L. In order to improve the production, several genetic and metabolic engineering approaches have been carried out. Genetically engineered organism has been reported to produce maximum of 50 g/L of isobutanol which is far more than the native strain without any modification. In bacteria mostly last two steps in Ehrlich pathway, catalyzed by enzymes ketoisovalerate decarboxylase and alcohol dehydrogenase, are heterologously expressed to improve the production. Native Saccharomyces cerevisiae can produce isobutanol in negligible amount since it possesses the pathway for its production through valine degradation pathway. Further modifications in the existing pathways made the improvement in isobutanol production in many microbial strains. Fermentation using cost-effective lignocellulosic biomass and an efficient downstream process can yield isobutanol in environment friendly and sustainable manner. The present review describes the various genetic and metabolic engineering practices adopted to improve the isobutanol production in microbial strains and its downstream processing.
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Affiliation(s)
- Nair M Lakshmi
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (Csir-niist), Thiruvananthapuram Kerala, India.,Academy of Scientific and Innovative Research (Acsir), Ghaziabad, Uttar Pradesh India
| | - Parameswaran Binod
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (Csir-niist), Thiruvananthapuram Kerala, India
| | - Raveendran Sindhu
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (Csir-niist), Thiruvananthapuram Kerala, India
| | - Mukesh Kumar Awasthi
- College of Natural Resources and Environment, North West a & F University, Yangling, Shaanxi China
| | - Ashok Pandey
- Centre for Innovation and Translational Research CSIR-Indian Institute of Toxicology Research (Csir-iitr), Lucknow India.,Centre for Energy and Environmental Sustainability, Lucknow Uttar Pradesh, India
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Metabolic engineering of Escherichia coli for the production of isobutanol: a review. World J Microbiol Biotechnol 2021; 37:168. [PMID: 34487256 DOI: 10.1007/s11274-021-03140-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 08/30/2021] [Indexed: 10/20/2022]
Abstract
With the ongoing depletion of fossil fuel resources and emerging environmental issues, increasing research effort is being dedicated to producing biofuels from renewable substrates. With its advantages over ethanol in terms of energy density, octane number, and hygroscopicity, isobutanol is considered a potential alternative to traditional gasoline. However, as wild-type microorganisms cannot achieve the production of isobutanol with high titers and yields, rational genetic engineering has been employed to enhance its production. Herein, we review the latest developments in the metabolic engineering of Escherichia coli for the production of isobutanol, including those related to the utilization of diverse carbon sources, balancing the redox state, improving isobutanol tolerance, and application of synthetic biology circuits and tools.
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Hoffman SM, Alvarez M, Alfassi G, Rein DM, Garcia-Echauri S, Cohen Y, Avalos JL. Cellulosic biofuel production using emulsified simultaneous saccharification and fermentation (eSSF) with conventional and thermotolerant yeasts. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:157. [PMID: 34274018 PMCID: PMC8285809 DOI: 10.1186/s13068-021-02008-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 07/05/2021] [Indexed: 05/16/2023]
Abstract
BACKGROUND Future expansion of corn-derived ethanol raises concerns of sustainability and competition with the food industry. Therefore, cellulosic biofuels derived from agricultural waste and dedicated energy crops are necessary. To date, slow and incomplete saccharification as well as high enzyme costs have hindered the economic viability of cellulosic biofuels, and while approaches like simultaneous saccharification and fermentation (SSF) and the use of thermotolerant microorganisms can enhance production, further improvements are needed. Cellulosic emulsions have been shown to enhance saccharification by increasing enzyme contact with cellulose fibers. In this study, we use these emulsions to develop an emulsified SSF (eSSF) process for rapid and efficient cellulosic biofuel production and make a direct three-way comparison of ethanol production between S. cerevisiae, O. polymorpha, and K. marxianus in glucose and cellulosic media at different temperatures. RESULTS In this work, we show that cellulosic emulsions hydrolyze rapidly at temperatures tolerable to yeast, reaching up to 40-fold higher conversion in the first hour compared to microcrystalline cellulose (MCC). To evaluate suitable conditions for the eSSF process, we explored the upper temperature limits for the thermotolerant yeasts Kluyveromyces marxianus and Ogataea polymorpha, as well as Saccharomyces cerevisiae, and observed robust fermentation at up to 46, 50, and 42 °C for each yeast, respectively. We show that the eSSF process reaches high ethanol titers in short processing times, and produces close to theoretical yields at temperatures as low as 30 °C. Finally, we demonstrate the transferability of the eSSF technology to other products by producing the advanced biofuel isobutanol in a light-controlled eSSF using optogenetic regulators, resulting in up to fourfold higher titers relative to MCC SSF. CONCLUSIONS The eSSF process addresses the main challenges of cellulosic biofuel production by increasing saccharification rate at temperatures tolerable to yeast. The rapid hydrolysis of these emulsions at low temperatures permits fermentation using non-thermotolerant yeasts, short processing times, low enzyme loads, and makes it possible to extend the process to chemicals other than ethanol, such as isobutanol. This transferability establishes the eSSF process as a platform for the sustainable production of biofuels and chemicals as a whole.
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Affiliation(s)
- Shannon M Hoffman
- Department of Chemical and Biological Engineering, Hoyt Laboratory, Princeton University, 101 Hoyt Laboratory, William Street, Princeton, NJ, 08544, USA
| | - Maria Alvarez
- Department of Chemical and Biological Engineering, Hoyt Laboratory, Princeton University, 101 Hoyt Laboratory, William Street, Princeton, NJ, 08544, USA
- Department of Chemical Engineering, University of Vigo, 36310, Vigo, Spain
| | - Gilad Alfassi
- Department of Biotechnology Engineering, ORT Braude College, Karmiel, Israel
| | - Dmitry M Rein
- Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Sergio Garcia-Echauri
- Department of Chemical and Biological Engineering, Hoyt Laboratory, Princeton University, 101 Hoyt Laboratory, William Street, Princeton, NJ, 08544, USA
| | - Yachin Cohen
- Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - José L Avalos
- Department of Chemical and Biological Engineering, Hoyt Laboratory, Princeton University, 101 Hoyt Laboratory, William Street, Princeton, NJ, 08544, USA.
- The Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ, USA.
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA.
- Princeton Environmental Institute, Princeton University, Princeton, NJ, 08544, USA.
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Acedos MG, de la Torre I, Santos VE, García-Ochoa F, García JL, Galán B. Modulating redox metabolism to improve isobutanol production in Shimwellia blattae. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:8. [PMID: 33407735 PMCID: PMC7789792 DOI: 10.1186/s13068-020-01862-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/17/2020] [Indexed: 05/04/2023]
Abstract
BACKGROUND Isobutanol is a candidate to replace gasoline from fossil resources. This higher alcohol can be produced from sugars using genetically modified microorganisms. Shimwellia blattae (p424IbPSO) is a robust strain resistant to high concentration of isobutanol that can achieve a high production rate of this alcohol. Nevertheless, this strain, like most strains developed for isobutanol production, has some limitations in its metabolic pathway. Isobutanol production under anaerobic conditions leads to a depletion of NADPH, which is necessary for two enzymes in the metabolic pathway. In this work, two independent approaches have been studied to mitigate the co-substrates imbalance: (i) using a NADH-dependent alcohol dehydrogenase to reduce the NADPH dependence of the pathway and (ii) using a transhydrogenase to increase NADPH level. RESULTS The addition of the NADH-dependent alcohol dehydrogenase from Lactococcus lactis (AdhA) to S. blattae (p424IbPSO) resulted in a 19.3% higher isobutanol production. The recombinant strain S. blattae (p424IbPSO, pIZpntAB) harboring the PntAB transhydrogenase produced 39.0% more isobutanol than the original strain, reaching 5.98 g L-1 of isobutanol. In both strains, we observed a significant decrease in the yields of by-products such as lactic acid or ethanol. CONCLUSIONS The isobutanol biosynthesis pathway in S. blattae (p424IbPSO) uses the endogenous NADPH-dependent alcohol dehydrogenase YqhD to complete the pathway. The addition of NADH-dependent AdhA leads to a reduction in the consumption of NADPH that is a bottleneck of the pathway. The higher consumption of NADH by AdhA reduces the availability of NADH required for the transformation of pyruvate into lactic acid and ethanol. On the other hand, the expression of PntAB from E. coli increases the availability of NADPH for IlvC and YqhD and at the same time reduces the availability of NADH and thus, the production of lactic acid and ethanol. In this work it is shown how the expression of AdhA and PntAB enzymes in Shimwellia blattae increases yield from 11.9% to 14.4% and 16.4%, respectively.
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Affiliation(s)
- Miguel G Acedos
- Chemical and Materials Engineering Department, Chemical Sciences School, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Isabel de la Torre
- Chemical and Materials Engineering Department, Chemical Sciences School, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Victoria E Santos
- Chemical and Materials Engineering Department, Chemical Sciences School, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Félix García-Ochoa
- Chemical and Materials Engineering Department, Chemical Sciences School, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - José L García
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas, CSIC, 28040, Madrid, Spain
| | - Beatriz Galán
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas, CSIC, 28040, Madrid, Spain.
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Biorefinery: The Production of Isobutanol from Biomass Feedstocks. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10228222] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Environmental issues have prompted the vigorous development of biorefineries that use agricultural waste and other biomass feedstock as raw materials. However, most current biorefinery products are cellulosic ethanol. There is an urgent need for biorefineries to expand into new bioproducts. Isobutanol is an important bulk chemical with properties that are close to gasoline, making it a very promising biofuel. The use of microorganisms to produce isobutanol has been extensively studied, but there is still a considerable gap to achieving the industrial production of isobutanol from biomass. This review summarizes current metabolic engineering strategies that have been applied to biomass isobutanol production and recent advances in the production of isobutanol from different biomass feedstocks.
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Tao W, Kasuga T, Li S, Huang H, Fan Z. Homoethanol production from cellobionate and glycerol using recombinant Klebsiella oxytoca strains. Biochem Eng J 2019. [DOI: 10.1016/j.bej.2019.107364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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13
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Homoethanol Production from Glycerol and Gluconate Using Recombinant Klebsiella oxytoca Strains. Appl Environ Microbiol 2019; 85:AEM.02122-18. [PMID: 30578264 DOI: 10.1128/aem.02122-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 11/30/2018] [Indexed: 11/20/2022] Open
Abstract
Gluconic acid, an oxidized cellulose degradation product, could be produced from cellulosic biomass. Glycerol is an inexpensive and renewable resource for fuels and chemicals production and is available as a byproduct of biodiesel production. Gluconate is a more oxidized substrate than glucose, whereas glycerol is a more reduced substrate than glucose. Although the production of homoethanol from glucose can be achieved, the conversion of gluconate to ethanol is accompanied by the production of oxidized byproduct such as acetate, and reduced byproducts such as 1,3-propanediol are produced, along with ethanol, when glycerol is used as the carbon source. When gluconate and glycerol are used as the sole carbon source by Klebsiella oxytoca BW21, the ethanol yield is about 62 to 64%. Coutilization of both gluconate and glycerol in batch fermentation increased the yield of ethanol to about 78.7% and decreased by-product accumulation (such as acetate and 1,3-propanediol) substantially. Decreasing by-product formation by deleting the pta, frd, ldh, pflA, and pduC genes in strain BW21 increased the ethanol yield to 89.3% in the batch fermentation of a glycerol-gluconate mixture. These deletions produced the strain K. oxytoca WT26. However, the utilization rate of glycerol was significantly slower than that of gluconate in batch fermentation. In addition, substantial amounts of glycerol remain unutilized after gluconate was depleted in batch fermentation. Continuous fed-batch fermentation was used to solve the utilization rate mismatch problem for gluconate and glycerol. An ethanol yield of 97.2% was achieved in continuous fed-batch fermentation of these two substrates, and glycerol was completely used at the end of the fermentation.IMPORTANCE Gluconate is a biomass-derived degradation product, and glycerol can be obtained as a biodiesel byproduct. Compared to glucose, using them as the sole substrate is accompanied by the production of by-products. Our study shows that through pathway engineering and adoption of a fed-batch culture system, high-yield homoethanol production that usually can be achieved by using glucose as the substrate is achievable using gluconate and glycerol as cosubstrates. The same strategy is expected to be able to achieve homofermentative production of other products, such as lactate and 2,3-butanediol, which can be typically achieved using glucose as the substrate and inexpensive biodiesel-derived glycerol and biomass-derived gluconate as the cosubstrates.
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Acedos MG, de la Torre I, Santos VE, Garcia-Ochoa F. Kinetic Modeling of the Isobutanol Production from Glucose Using Shimwellia blattae (p424IbPSO) Strain: Effect of Initial Substrate Concentration. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.8b05121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Miguel G. Acedos
- Chemical & Materials Engineering Department, Universidad Complutense, 28040 Madrid, Spain
| | - Isabel de la Torre
- Chemical & Materials Engineering Department, Universidad Complutense, 28040 Madrid, Spain
| | - Victoria E. Santos
- Chemical & Materials Engineering Department, Universidad Complutense, 28040 Madrid, Spain
| | - Felix Garcia-Ochoa
- Chemical & Materials Engineering Department, Universidad Complutense, 28040 Madrid, Spain
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15
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Photomixotrophic chemical production in cyanobacteria. Curr Opin Biotechnol 2018; 50:65-71. [DOI: 10.1016/j.copbio.2017.11.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/11/2017] [Accepted: 11/13/2017] [Indexed: 11/19/2022]
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16
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Miao R, Xie H, Lindblad P. Enhancement of photosynthetic isobutanol production in engineered cells of Synechocystis PCC 6803. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:267. [PMID: 30275907 PMCID: PMC6158846 DOI: 10.1186/s13068-018-1268-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 09/20/2018] [Indexed: 05/23/2023]
Abstract
BACKGROUND Cyanobacteria, oxygenic photoautotrophic prokaryotes, can be engineered to produce various valuable chemicals from solar energy and CO2 in direct processes. The concept of photosynthetic production of isobutanol, a promising chemical and drop-in biofuel, has so far been demonstrated for Synechocystis PCC 6803 and Synechococcus elongatus PCC 7942. In Synechocystis PCC 6803, a heterologous expression of α-ketoisovalerate decarboxylase (Kivd) from Lactococcus lactis resulted in an isobutanol and 3-methyl-1-butanol producing strain. Kivd was identified as a bottleneck in the metabolic pathway and its activity was further improved by reducing the size of its substrate-binding pocket with a single replacement of serine-286 to threonine (KivdS286T). However, isobutanol production still remained low. RESULTS In the present study, we report on how cultivation conditions significantly affect the isobutanol production in Synechocystis PCC 6803. A HCl-titrated culture grown under medium light (50 μmol photons m-2 s-1) showed the highest isobutanol production with an in-flask titer of 194 mg l-1 after 10 days and 435 mg l-1 at day 40. This corresponds to a cumulative isobutanol production of 911 mg l-1, with a maximal production rate of 43.6 mg l-1 day-1 observed between days 4 and 6. Additional metabolic bottlenecks in the isobutanol biosynthesis pathway were further addressed. The expression level of KivdS286T was significantly affected when co-expressed with another gene downstream in a single operon and in a convergent oriented operon. Moreover, the expression of the ADH encoded by codon-optimized slr1192 and co-expression of IlvC and IlvD were identified as potential approaches to further enhance isobutanol production in Synechocystis PCC 6803. CONCLUSION The present study demonstrates the importance of a suitable cultivation condition to enhance isobutanol production in Synechocystis PCC 6803. Chemostat should be used to further increase both the total titer as well as the rate of production. Furthermore, identified bottleneck, Kivd, should be expressed at the highest level to further enhance isobutanol production.
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Affiliation(s)
- Rui Miao
- Microbial Chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
| | - Hao Xie
- Microbial Chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
| | - Peter Lindblad
- Microbial Chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
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17
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Mao S, Liu Y, Hou Y, Ma X, Yang J, Han H, Wu J, Jia L, Qin H, Lu F. Efficient production of sugar-derived aldonic acids by Pseudomonas fragi TCCC11892. RSC Adv 2018; 8:39897-39901. [PMID: 35558231 PMCID: PMC9091311 DOI: 10.1039/c8ra07556e] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/18/2018] [Indexed: 11/21/2022] Open
Abstract
Pseudomonas fragi TCCC11892 was found to be an efficient producer of aldonic acids which are receiving increased interest due to their applications in nanotechnology, food, pharmaceutical and chemical industries.
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18
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Miao R, Liu X, Englund E, Lindberg P, Lindblad P. Isobutanol production in Synechocystis PCC 6803 using heterologous and endogenous alcohol dehydrogenases. Metab Eng Commun 2017; 5:45-53. [PMID: 29188183 PMCID: PMC5699533 DOI: 10.1016/j.meteno.2017.07.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 07/18/2017] [Accepted: 07/27/2017] [Indexed: 12/24/2022] Open
Abstract
Isobutanol is a flammable compound that can be used as a biofuel due to its high energy density and suitable physical and chemical properties. In this study, we examined the capacity of engineered strains of Synechocystis PCC 6803 containing the α-ketoisovalerate decarboxylase from Lactococcus lactis and different heterologous and endogenous alcohol dehydrogenases (ADH) for isobutanol production. A strain expressing an introduced kivd without any additional copy of ADH produced 3 mg L-1 OD750-1 isobutanol in 6 days. After the cultures were supplemented with external addition of isobutyraldehyde, the substrate for ADH, 60.8 mg L-1 isobutanol was produced after 24 h when OD750 was 0.8. The in vivo activities of four different ADHs, two heterologous and two putative endogenous in Synechocystis, were examined and the Synechocystis endogenous ADH encoded by slr1192 showed the highest efficiency for isobutanol production. Furthermore, the strain overexpressing the isobutanol pathway on a self-replicating vector with the strong Ptrc promoter showed significantly higher gene expression and isobutanol production compared to the corresponding strains expressing the same operon introduced on the genome. Hence, this study demonstrates that Synechocystis endogenous AHDs have a high capacity for isobutanol production, and identifies kivd encoded α-ketoisovalerate decarboxylase as one of the likely bottlenecks for further isobutanol production.
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Affiliation(s)
| | | | | | | | - Peter Lindblad
- Microbial chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden
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19
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Retooling microorganisms for the fermentative production of alcohols. Curr Opin Biotechnol 2017; 50:1-10. [PMID: 28888164 DOI: 10.1016/j.copbio.2017.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 12/31/2022]
Abstract
Bioengineering and synthetic biology approaches have revolutionised the field of biotechnology, enabling the introduction of non-native and de novo pathways for biofuels production. This 'retooling' of microorganisms is also applied to the utilisation of mixed carbon components derived from lignocellulosic biomass, a major technical barrier for the development of economically viable fermentations. This review will discuss recent advances in microorganism engineering for efficient production of alcohols from waste biomass. These advances span the introduction of new pathways to alcohols, host modifications for more cost-effective utilisation of lignocellulosic waste and modifications of existing pathways for generating new fuel additives.
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20
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Davis D, Doloman A, Podgorski GJ, Vargis E, Flann NS. Exploiting Self-organization in Bioengineered Systems: A Computational Approach. Front Bioeng Biotechnol 2017; 5:27. [PMID: 28503548 PMCID: PMC5408088 DOI: 10.3389/fbioe.2017.00027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 04/03/2017] [Indexed: 11/13/2022] Open
Abstract
The productivity of bioengineered cell factories is limited by inefficiencies in nutrient delivery and waste and product removal. Current solution approaches explore changes in the physical configurations of the bioreactors. This work investigates the possibilities of exploiting self-organizing vascular networks to support producer cells within the factory. A computational model simulates de novo vascular development of endothelial-like cells and the resultant network functioning to deliver nutrients and extract product and waste from the cell culture. Microbial factories with vascular networks are evaluated for their scalability, robustness, and productivity compared to the cell factories without a vascular network. Initial studies demonstrate that at least an order of magnitude increase in production is possible, the system can be scaled up, and the self-organization of an efficient vascular network is robust. The work suggests that bioengineered multicellularity may offer efficiency improvements difficult to achieve with physical engineering approaches.
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Affiliation(s)
- Delin Davis
- Computer Science Department, Utah State University, Logan, UT, USA
| | - Anna Doloman
- Department of Biological Engineering, Utah State University, Logan, UT, USA
| | | | - Elizabeth Vargis
- Department of Biological Engineering, Utah State University, Logan, UT, USA
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21
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Lin H, Hildebrand A, Kasuga T, Fan Z. Engineering Neurospora crassa for cellobionate production directly from cellulose without any enzyme addition. Enzyme Microb Technol 2017; 99:25-31. [DOI: 10.1016/j.enzmictec.2016.12.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 12/27/2016] [Accepted: 12/28/2016] [Indexed: 10/20/2022]
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22
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Wong SS, Mi L, Liao JC. Microbial Production of Butanols. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1002/9783527807833.ch19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Sio Si Wong
- University of California; Department of Chemical and Biomolecular Engineering; 420 Westwood Plaza, 5531Boelter Hall Los Angeles CA 90095 USA
| | - Luo Mi
- University of California; Department of Chemical and Biomolecular Engineering; 420 Westwood Plaza, 5531Boelter Hall Los Angeles CA 90095 USA
| | - James C. Liao
- University of California; Department of Chemical and Biomolecular Engineering; 420 Westwood Plaza, 5531Boelter Hall Los Angeles CA 90095 USA
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23
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Corrêa TLR, dos Santos LV, Pereira GAG. AA9 and AA10: from enigmatic to essential enzymes. Appl Microbiol Biotechnol 2016; 100:9-16. [PMID: 26476647 DOI: 10.1007/s00253-015-7040-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 09/20/2015] [Accepted: 09/24/2015] [Indexed: 12/15/2022]
Abstract
The lignocellulosic biomass, comprised mainly of cellulose, hemicellulose, and lignin, is a strong competitor for petroleum to obtain fuels and other products because of its renewable nature, low cost, and non-competitiveness with food production when obtained from agricultural waste. Due to its recalcitrance, lignocellulosic material requires an arsenal of enzymes for its deconstruction and the consequent release of fermentable sugars. In this context, enzymes currently classified as auxiliary activity 9 (AA9/formerly GH61) and 10 (AA10/formerly CBM 33) or lytic polysaccharide monooxygenases (LPMO) have emerged as cellulase boosting enzymes. AA9 and AA10 are the new paradigm for deconstruction of lignocellulosic biomass by enhancing the activity and decreasing the loading of classical enzymes to the reaction and, consequently, reducing costs of the hydrolysis step in the second-generation ethanol production chain. In view of that disclosed above, the goal of this work is to review experimental data that supports the relevance of AA9 and AA10 for the biomass deconstruction field.
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24
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Desai SH, Koryakina I, Case AE, Toney MD, Atsumi S. Biological conversion of gaseous alkenes to liquid chemicals. Metab Eng 2016; 38:98-104. [PMID: 27424209 DOI: 10.1016/j.ymben.2016.07.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/11/2016] [Indexed: 10/21/2022]
Abstract
Industrial gas-to-liquid (GTL) technologies are well developed. They generally employ syngas, require complex infrastructure, and need high capital investment to be economically viable. Alternatively, biological conversion has the potential to be more efficient, and easily deployed to remote areas on relatively small scales for the utilization of otherwise stranded resources. The present study demonstrates a novel biological GTL process in which engineered Escherichia coli converts C2-C4 gaseous alkenes into liquid diols. Diols are versatile industrially important chemicals, used routinely as antifreeze agents, polymer precursors amongst many other applications. Heterologous co-expression of a monooxygenase and an epoxide hydrolase in E. coli allows whole cell conversion of C2-C4 alkenes for the formation of ethylene glycol, 1,2-propanediol, 1,2-butanediol, and 2,3-butanediol at ambient temperature and pressure in one pot. Increasing intracellular NADH supply via addition of formate and a formate dehydrogenase increases ethylene glycol production titers, resulting in an improved productivity of 9mg/L/h and a final titer of 250mg/L. This represents a novel biological method for GTL conversion of alkenes to industrially valuable diols.
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Affiliation(s)
- Shuchi H Desai
- Department of Chemistry, University of California-Davis, Davis, CA, USA
| | - Irina Koryakina
- Department of Chemistry, University of California-Davis, Davis, CA, USA
| | - Anna E Case
- Department of Chemistry, University of California-Davis, Davis, CA, USA
| | - Michael D Toney
- Department of Chemistry, University of California-Davis, Davis, CA, USA.
| | - Shota Atsumi
- Department of Chemistry, University of California-Davis, Davis, CA, USA.
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25
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Kang A, Lee TS. Converting Sugars to Biofuels: Ethanol and Beyond. Bioengineering (Basel) 2015; 2:184-203. [PMID: 28952477 PMCID: PMC5597089 DOI: 10.3390/bioengineering2040184] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 10/15/2015] [Accepted: 10/20/2015] [Indexed: 11/16/2022] Open
Abstract
To date, the most significant sources of biofuels are starch- or sugarcane-based ethanol, which have been industrially produced in large quantities in the USA and Brazil, respectively. However, the ultimate goal of biofuel production is to produce fuels from lignocellulosic biomass-derived sugars with optimal fuel properties and compatibility with the existing fuel distribution infrastructure. To achieve this goal, metabolic pathways have been constructed to produce various fuel molecules that are categorized into fermentative alcohols (butanol and isobutanol), non-fermentative alcohols from 2-keto acid pathways, fatty acids-derived fuels and isoprenoid-derived fuels. This review will focus on current metabolic engineering efforts to improve the productivity and the yield of several key biofuel molecules. Strategies used in these metabolic engineering efforts can be summarized as follows: (1) identification of better enzymes; (2) flux control of intermediates and precursors; (3) elimination of competing pathways; (4) redox balance and cofactor regeneration; and (5) bypassing regulatory mechanisms. In addition to metabolic engineering approaches, host strains are optimized by improving sugar uptake and utilization, and increasing tolerance to toxic hydrolysates, metabolic intermediates and/or biofuel products.
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Affiliation(s)
- Aram Kang
- Joint BioEnergy Institute, Emeryville, CA 94608, USA.
- Biological Systems & Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | - Taek Soon Lee
- Joint BioEnergy Institute, Emeryville, CA 94608, USA.
- Biological Systems & Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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26
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Kitaoka M. Diversity of phosphorylases in glycoside hydrolase families. Appl Microbiol Biotechnol 2015; 99:8377-90. [PMID: 26293338 DOI: 10.1007/s00253-015-6927-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/05/2015] [Indexed: 01/02/2023]
Abstract
Phosphorylases are useful catalysts for the practical preparation of various sugars. The number of known specificities was 13 in 2002 and is now 30. The drastic increase in available genome sequences has facilitated the discovery of novel activities. Most of these novel phosphorylase activities have been identified through the investigations of glycoside hydrolase families containing known phosphorylases. Here, the diversity of phosphorylases in each family is described in detail.
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Affiliation(s)
- Motomitsu Kitaoka
- National Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki, 305-8642, Japan.
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27
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Li X, Chomvong K, Yu VY, Liang JM, Lin Y, Cate JHD. Cellobionic acid utilization: from Neurospora crassa to Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:120. [PMID: 26279678 PMCID: PMC4537572 DOI: 10.1186/s13068-015-0303-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 07/31/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND Economical production of fuels and chemicals from plant biomass requires the efficient use of sugars derived from the plant cell wall. Neurospora crassa, a model lignocellulosic degrading fungus, is capable of breaking down the complex structure of the plant cell wall. In addition to cellulases and hemicellulases, N. crassa secretes lytic polysaccharide monooxygenases (LPMOs), which cleave cellulose by generating oxidized sugars-particularly aldonic acids. However, the strategies N. crassa employs to utilize these sugars are unknown. RESULTS We identified an aldonic acid utilization pathway in N. crassa, comprised of an extracellular hydrolase (NCU08755), cellobionic acid transporter (CBT-1, NCU05853) and cellobionic acid phosphorylase (CAP, NCU09425). Extracellular cellobionic acid could be imported directly by CBT-1 or cleaved to gluconic acid and glucose by a β-glucosidase (NCU08755) outside the cells. Intracellular cellobionic acid was further cleaved to glucose 1-phosphate and gluconic acid by CAP. However, it remains unclear how N. crassa utilizes extracellular gluconic acid. The aldonic acid pathway was successfully implemented in Saccharomyces cerevisiae when N. crassa gluconokinase was co-expressed, resulting in cellobionic acid consumption in both aerobic and anaerobic conditions. CONCLUSIONS We successfully identified a branched aldonic acid utilization pathway in N. crassa and transferred its essential components into S. cerevisiae, a robust industrial microorganism.
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Affiliation(s)
- Xin Li
- />Department of Molecular and Cell Biology, University of California, Berkeley, CA USA
| | - Kulika Chomvong
- />Department of Plant and Microbial Biology, University of California, Berkeley, CA USA
| | - Vivian Yaci Yu
- />Department of Molecular and Cell Biology, University of California, Berkeley, CA USA
| | - Julie M Liang
- />Department of Chemistry, University of California, Berkeley, CA USA
| | - Yuping Lin
- />Department of Molecular and Cell Biology, University of California, Berkeley, CA USA
| | - Jamie H D Cate
- />Department of Molecular and Cell Biology, University of California, Berkeley, CA USA
- />Department of Chemistry, University of California, Berkeley, CA USA
- />Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA USA
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28
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Nam YW, Nihira T, Arakawa T, Saito Y, Kitaoka M, Nakai H, Fushinobu S. Crystal Structure and Substrate Recognition of Cellobionic Acid Phosphorylase, Which Plays a Key Role in Oxidative Cellulose Degradation by Microbes. J Biol Chem 2015; 290:18281-92. [PMID: 26041776 DOI: 10.1074/jbc.m115.664664] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Indexed: 01/02/2023] Open
Abstract
The microbial oxidative cellulose degradation system is attracting significant research attention after the recent discovery of lytic polysaccharide mono-oxygenases. A primary product of the oxidative and hydrolytic cellulose degradation system is cellobionic acid (CbA), the aldonic acid form of cellobiose. We previously demonstrated that the intracellular enzyme belonging to glycoside hydrolase family 94 from cellulolytic fungus and bacterium is cellobionic acid phosphorylase (CBAP), which catalyzes reversible phosphorolysis of CbA into glucose 1-phosphate and gluconic acid (GlcA). In this report, we describe the biochemical characterization and the three-dimensional structure of CBAP from the marine cellulolytic bacterium Saccharophagus degradans. Structures of ligand-free and complex forms with CbA, GlcA, and a synthetic disaccharide product from glucuronic acid were determined at resolutions of up to 1.6 Å. The active site is located near the dimer interface. At subsite +1, the carboxylate group of GlcA and CbA is recognized by Arg-609 and Lys-613. Additionally, one residue from the neighboring protomer (Gln-190) is involved in the carboxylate recognition of GlcA. A mutational analysis indicated that these residues are critical for the binding and catalysis of the aldonic and uronic acid acceptors GlcA and glucuronic acid. Structural and sequence comparisons with other glycoside hydrolase family 94 phosphorylases revealed that CBAPs have a unique subsite +1 with a distinct amino acid residue conservation pattern at this site. This study provides molecular insight into the energetically efficient metabolic pathway of oxidized sugars that links the oxidative cellulolytic pathway to the glycolytic and pentose phosphate pathways in cellulolytic microbes.
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Affiliation(s)
- Young-Woo Nam
- From the Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takanori Nihira
- Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan, and
| | - Takatoshi Arakawa
- From the Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yuka Saito
- Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan, and
| | - Motomitsu Kitaoka
- National Food Research Institute, National Agriculture and Food Research Organization, Tsukuba, Ibaraki 305-8642, Japan
| | - Hiroyuki Nakai
- Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan, and
| | - Shinya Fushinobu
- From the Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan,
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