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Branska B, Koppova K, Husakova M, Patakova P. Application of fed-batch strategy to fully eliminate the negative effect of lignocellulose-derived inhibitors in ABE fermentation. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:87. [PMID: 38915101 PMCID: PMC11197323 DOI: 10.1186/s13068-024-02520-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 05/16/2024] [Indexed: 06/26/2024]
Abstract
BACKGROUND Inhibitors that are released from lignocellulose biomass during its treatment represent one of the major bottlenecks hindering its massive utilization in the biotechnological production of chemicals. This study demonstrates that negative effect of inhibitors can be mitigated by proper feeding strategy. Both, crude undetoxified lignocellulose hydrolysate and complex medium supplemented with corresponding inhibitors were tested in acetone-butanol-ethanol (ABE) fermentation using Clostridium beijerinckii NRRL B-598 as the producer strain. RESULTS First, it was found that the sensitivity of C. beijerinckii to inhibitors varied with different growth stages, being the most significant during the early acidogenic phase and less pronounced during late acidogenesis and early solventogenesis. Thus, a fed-batch regime with three feeding schemes was tested for toxic hydrolysate (no growth in batch mode was observed). The best results were obtained when the feeding of an otherwise toxic hydrolysate was initiated close to the metabolic switch, resulting in stable and high ABE production. Complete utilization of glucose, and up to 88% of xylose, were obtained. The most abundant inhibitors present in the alkaline wheat straw hydrolysate were ferulic and coumaric acids; both phenolic acids were efficiently detoxified by the intrinsic metabolic activity of clostridia during the early stages of cultivation as well as during the feeding period, thus preventing their accumulation. Finally, the best feeding strategy was verified using a TYA culture medium supplemented with both inhibitors, resulting in 500% increase in butanol titer over control batch cultivation in which inhibitors were added prior to inoculation. CONCLUSION Properly timed sequential feeding effectively prevented acid-crash and enabled utilization of otherwise toxic substrate. This study unequivocally demonstrates that an appropriate biotechnological process control strategy can fully eliminate the negative effects of lignocellulose-derived inhibitors.
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Affiliation(s)
- Barbora Branska
- Department of Biotechnology, University of Chemistry and Technology Prague, Technická 5, 16628, Prague, Czech Republic.
| | - Kamila Koppova
- Department of Biotechnology, University of Chemistry and Technology Prague, Technická 5, 16628, Prague, Czech Republic
| | - Marketa Husakova
- Department of Biotechnology, University of Chemistry and Technology Prague, Technická 5, 16628, Prague, Czech Republic
| | - Petra Patakova
- Department of Biotechnology, University of Chemistry and Technology Prague, Technická 5, 16628, Prague, Czech Republic
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2
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Ujor VC, Okonkwo CC. Microbial detoxification of lignocellulosic biomass hydrolysates: Biochemical and molecular aspects, challenges, exploits and future perspectives. Front Bioeng Biotechnol 2022; 10:1061667. [PMID: 36483774 PMCID: PMC9723337 DOI: 10.3389/fbioe.2022.1061667] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 10/31/2022] [Indexed: 08/26/2023] Open
Abstract
Valorization of lignocellulosic biomass (LB) has the potential to secure sustainable energy production without impacting food insecurity, whist relieving over reliance on finite fossil fuels. Agro-derived lignocellulosic residues such as wheat straw, switchgrass, rice bran, and miscanthus have gained relevance as feedstocks for the production of biofuels and chemicals. However, the microorganisms employed in fermentative conversion of carbohydrates to fuels and chemicals are unable to efficiently utilize the sugars derived from LB due to co-production of lignocellulose-derived microbial inhibitory compounds (LDMICs) during LB pretreatment. LDMICs impact microbial growth by inhibition of specific enzymes, cause DNA and cell membrane damage, and elicit cellular redox imbalance. Over the past decade, success has been achieved with the removal of LDMICs prior to fermentation. However, LDMICs removal by chemical processes is often accompanied by sugar losses, which negatively impacts the overall production cost. Hence, in situ removal of LDMICs by fermentative organisms during the fermentation process has garnered considerable attention as the "go-to" approach for economical LDMICs detoxification and bio-chemicals production. In situ removal of LDMICs has been pursued by either engineering more robust biocatalysts or isolating novel microbial strains with the inherent capacity to mineralize or detoxify LDMICs to less toxic compounds. While some success has been made along this line, efficient detoxification and robust production of target bio-chemicals in lignocellulosic hydrolysates (LHs) under largely anaerobic fermentative conditions remains a lingering challenge. Consequently, LB remains an underutilized substrate for bio-chemicals production. In this review, the impact of microbial LH detoxification on overall target molecule production is discussed. Further, the biochemical pathways and mechanisms employed for in situ microbial detoxification of furanic LDMICs [e.g., furfural and 5-hydroxymethylfurfural (HMF)] and phenolic LDMICs (e.g., syringaldehyde, p-coumaric acid, 4-hydroxybenzaldehyde, vanillin, and ferulic acid) are discussed. More importantly, metabolic engineering strategies for the development of LDMIC-tolerant and bio-chemicals overproducing strains and processes are highlighted.
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Affiliation(s)
- Victor C. Ujor
- Metabolic Engineering and Fermentation Science Group, Department of Food Science, University of Wisconsin-Madison, Madison, WI, United States
| | - Christopher C. Okonkwo
- Biotechnology Program, College of Science, The Roux Institute, Northeastern University, Portland, ME, United States
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3
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Mechanistic Insight into Phenolic Compounds Toxicity and State-of-the-art Strategies for Enhancing the Tolerance of Escherichia coli to Phenolic Compounds. BIOTECHNOL BIOPROC E 2022. [DOI: 10.1007/s12257-022-0019-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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4
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Liu L, Ma X, Bilal M, Wei L, Tang S, Luo H, Zhao Y, Wang Z, Duan X. Toxicity and inhibition mechanism of gallic acid on physiology and fermentation performance of Escherichia coli. BIORESOUR BIOPROCESS 2022; 9:76. [PMID: 38647760 PMCID: PMC10992115 DOI: 10.1186/s40643-022-00564-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: 04/23/2022] [Accepted: 07/10/2022] [Indexed: 11/10/2022] Open
Abstract
Gallic acid is a natural phenolic acid that has a stress inhibition effect on Escherichia coli. This study by integrates fermentation characteristics and transcriptional analyses to elucidate the physiological mechanism of E. coli 3110 response to gallic acid. Compared with the control (without stress), the cell growth was severely retarded, and irregular cell morphology appeared in the case of high levels of gallic acid stress. The glucose consumption of E. coli was reduced successively with the increase of gallic acid content in the fermentation medium. After 20 h of gallic acid stress, cofactor levels (ATP, NAD+ and NADH) of E. coli 3110 were similarly decreased, indicating a more potent inhibitory effect of gallic acid on E. coli. The transcriptional analysis revealed that gallic acid altered the gene expression profiles related to five notable differentially regulated pathways. The genes related to the two-component system were up-regulated, while the genes associated with ABC-transporter, energy metabolism, carbon metabolism, and fatty acid biosynthesis were down-regulated. This is the first report to comprehensively assess the toxicity of gallic acid on E. coli. This study has implications for the efficient production of phenolic compounds by E. coli and provides new ideas for the study of microbial tolerance to environmental stress and the identification of associated tolerance targets.
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Affiliation(s)
- Lina Liu
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China.
| | - Xiaolong Ma
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China
| | - Muhammad Bilal
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China
| | - Linlin Wei
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China
| | - Shijie Tang
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China
| | - Hongzhen Luo
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China
| | - Yuping Zhao
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China
| | - Zhaoyu Wang
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China
| | - Xuguo Duan
- College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China
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5
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Yi X, Wu J, Jiang H, Zhao Y, Mei J. Kinase expression enhances phenolic aldehydes conversion and ethanol fermentability of Zymomonas mobilis. Bioprocess Biosyst Eng 2022; 45:1319-1329. [PMID: 35786774 DOI: 10.1007/s00449-022-02747-3] [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: 03/28/2022] [Accepted: 06/11/2022] [Indexed: 11/26/2022]
Abstract
Kinases modulate the various physiological activities of microbial fermenting strains including the conversion of lignocellulose-derived phenolic aldehydes (4-hydroxyaldehyde, vanillin, and syringaldehyde). Here, we comprehensively investigated the gene transcriptional profiling of the kinases under the stress of phenolic aldehydes for ethanologenic Zymomonas mobilis using DNA microarray. Among 47 kinase genes, three genes of ZMO0003 (adenylylsulfate kinase), ZMO1162 (histidine kinase), and ZMO1391 (diacylglycerol kinase), were differentially expressed against 4-hydroxybenzaldehyde and vanillin, in which the overexpression of ZMO1162 promoted the phenolic aldehydes conversion and ethanol fermentability. The perturbance originated from plasmid-based expression of ZMO1162 gene contributed to a unique expression profiling of genome-encoding genes under all three phenolic aldehydes stress. Differentially expressed ribosome genes were predicted as one of the main contributors to phenolic aldehydes conversion and thus finally enhanced ethanol fermentability for Z. mobilis ZM4. The results provided an insight into the kinases on regulation of phenolic aldehydes conversion and ethanol fermentability for Z. mobilis ZM4, as well as the target object for rational design of robust biorefinery strains.
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Affiliation(s)
- Xia Yi
- Jiangxi Provincial Key Laboratory of Systems Biomedicine, Jiujiang University, 17 Lufeng Road, Jiujiang, 332000, China.
- National-Local Joint Engineering Research Center for Biomass Refining and High-Quality Utilization, Changzhou University, Changzhou, 213164, China.
| | - Jianfang Wu
- Jiangxi Provincial Key Laboratory of Systems Biomedicine, Jiujiang University, 17 Lufeng Road, Jiujiang, 332000, China
| | - He Jiang
- Jiangxi Provincial Key Laboratory of Systems Biomedicine, Jiujiang University, 17 Lufeng Road, Jiujiang, 332000, China
| | - Yan Zhao
- Jiangxi Provincial Key Laboratory of Systems Biomedicine, Jiujiang University, 17 Lufeng Road, Jiujiang, 332000, China
| | - Jun Mei
- Jiangxi Provincial Key Laboratory of Systems Biomedicine, Jiujiang University, 17 Lufeng Road, Jiujiang, 332000, China
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6
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Patakova P, Branska B, Vasylkivska M, Jureckova K, Musilova J, Provaznik I, Sedlar K. Transcriptomic studies of solventogenic clostridia, Clostridium acetobutylicum and Clostridium beijerinckii. Biotechnol Adv 2021; 58:107889. [PMID: 34929313 DOI: 10.1016/j.biotechadv.2021.107889] [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: 08/27/2021] [Revised: 12/10/2021] [Accepted: 12/14/2021] [Indexed: 12/13/2022]
Abstract
Solventogenic clostridia are not a strictly defined group within the genus Clostridium but its representatives share some common features, i.e. they are anaerobic, non-pathogenic, non-toxinogenic and endospore forming bacteria. Their main metabolite is typically 1-butanol but depending on species and culture conditions, they can form other metabolites such as acetone, isopropanol, ethanol, butyric, lactic and acetic acids, and hydrogen. Although these organisms were previously used for the industrial production of solvents, they later fell into disuse, being replaced by more efficient chemical production. A return to a more biological production of solvents therefore requires a thorough understanding of clostridial metabolism. Transcriptome analysis, which reflects the involvement of individual genes in all cellular processes within a population, at any given (sampling) moment, is a valuable tool for gaining a deeper insight into clostridial life. In this review, we describe techniques to study transcription, summarize the evolution of these techniques and compare methods for data processing and visualization of solventogenic clostridia, particularly the species Clostridium acetobutylicum and Clostridium beijerinckii. Individual approaches for evaluating transcriptomic data are compared and their contributions to advancements in the field are assessed. Moreover, utilization of transcriptomic data for reconstruction of computational clostridial metabolic models is considered and particular models are described. Transcriptional changes in glucose transport, central carbon metabolism, the sporulation cycle, butanol and butyrate stress responses, the influence of lignocellulose-derived inhibitors on growth and solvent production, and other respective topics, are addressed and common trends are highlighted.
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Affiliation(s)
- Petra Patakova
- University of Chemistry and Technology Prague, Technicka 5, 16628 Prague 6, Czech Republic.
| | - Barbora Branska
- University of Chemistry and Technology Prague, Technicka 5, 16628 Prague 6, Czech Republic
| | - Maryna Vasylkivska
- University of Chemistry and Technology Prague, Technicka 5, 16628 Prague 6, Czech Republic
| | | | - Jana Musilova
- Brno University of Technology, Technicka 10, 61600 Brno, Czech Republic
| | - Ivo Provaznik
- Brno University of Technology, Technicka 10, 61600 Brno, Czech Republic
| | - Karel Sedlar
- Brno University of Technology, Technicka 10, 61600 Brno, Czech Republic
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7
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Yi X, Lin L, Mei J, Wang W. Transporter proteins in Zymomonas mobilis contribute to the tolerance of lignocellulose-derived phenolic aldehyde inhibitors. Bioprocess Biosyst Eng 2021; 44:1875-1882. [PMID: 33839896 DOI: 10.1007/s00449-021-02567-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/31/2021] [Indexed: 01/29/2023]
Abstract
Transporter proteins are of great importance for improving the tolerance of fermentation strains to lignocellulose-derived furans and phenolic inhibitors. Different from the documented transporter proteins responsible for the tolerance of furfural and 5-hydroxymethyl-furfural (HMF), transporters responsible for that of varied phenolic aldehyde inhibitors were less investigated and elucidated. Here, an interesting phenomenon was found that no phenolic alcohols were accumulated from phenolic aldehydes degradation in Zymomonas mobilis. A transcriptional profiling of transporter genes was established in Z. mobilis ZM4 under phenolic aldehydes stress using DNA microarray. Six transporter proteins were identified as the potential candidates responsible for the tolerance of phenolic aldehydes including ABC transporter (ZMO0799 and ZMO0800), MFS transporter (ZMO1288 and ZMO1856), and RND transporter (ZMO0282 and ZMO0798). Furthermore, the analysis showed that the key transporters were significantly correlated with oxidoreductases and transcriptional regulators. This work would provide several important transporter genes serving as synthetic biology tools for improving the robustness of biorefinery strains.
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Affiliation(s)
- Xia Yi
- Jiangxi Provincial Key Laboratory of Systems Biomedicine, Jiujiang University, 17 Lufeng Road, Jiujiang, 332000, China.
| | - Ling Lin
- Jiangxi Provincial Key Laboratory of Systems Biomedicine, Jiujiang University, 17 Lufeng Road, Jiujiang, 332000, China
| | - Jun Mei
- Jiangxi Provincial Key Laboratory of Systems Biomedicine, Jiujiang University, 17 Lufeng Road, Jiujiang, 332000, China
| | - Wei Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
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8
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Jiménez-Bonilla P, Zhang J, Wang Y, Blersch D, de-Bashan LE, Guo L, Wang Y. Enhancing the tolerance of Clostridium saccharoperbutylacetonicum to lignocellulosic-biomass-derived inhibitors for efficient biobutanol production by overexpressing efflux pumps genes from Pseudomonas putida. BIORESOURCE TECHNOLOGY 2020; 312:123532. [PMID: 32502888 DOI: 10.1016/j.biortech.2020.123532] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 04/30/2020] [Accepted: 05/02/2020] [Indexed: 06/11/2023]
Abstract
Furan aldehydes and phenolic compounds generated during biomass pretreatment can inhibit fermentation for biofuel production. Efflux pumps actively transport small molecules out of cells, thus sustaining normal microbial metabolism. Pseudomonas putida has outstanding tolerance to butanol and other small molecules, and we hypothesize that its efflux pump could play essential roles for such robustness. Here, we overexpressed efflux pump genes from P. putida to enhance tolerance of hyper-butanol producing Clostridium saccharoperbutylacetonicum to fermentation inhibitors. Interestingly, overexpression of the whole unit resulted in decreased tolerance, while overexpression of the subunit (srpB) alone exerted significant enhanced robustness of the strain. Compared to the control, the engineered strain had enhanced capability to grow in media containing 17% more furfural or 50% more ferulic acid, and produced ~14 g/L butanol (comparable to fermentation under regular conditions without inhibitors). This study provided valuable reference for boosting microbial robustness towards efficient biofuel production from lignocellulosic materials.
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Affiliation(s)
- Pablo Jiménez-Bonilla
- Department of Biosystems Engineering, Auburn University, Auburn, AL 36849, USA; School of Chemistry, National University (UNA), Heredia, Costa Rica
| | - Jie Zhang
- Department of Biosystems Engineering, Auburn University, Auburn, AL 36849, USA
| | - Yifen Wang
- Department of Biosystems Engineering, Auburn University, Auburn, AL 36849, USA; Center for Bioenergy and Bioproducts, Auburn University, Auburn, AL 36849, USA
| | - David Blersch
- Department of Biosystems Engineering, Auburn University, Auburn, AL 36849, USA
| | - Luz-Estela de-Bashan
- Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), Av. IPN 195, La Paz, B.C.S. 23096, Mexico; The Bashan Institute of Science, 1730 Post Oak Court, Auburn, AL 36830, USA; Department of Entomology and Plant Pathology, Auburn University, 301 Funchess Hall, Auburn, AL 36849, USA
| | - Liang Guo
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Yi Wang
- Department of Biosystems Engineering, Auburn University, Auburn, AL 36849, USA; Center for Bioenergy and Bioproducts, Auburn University, Auburn, AL 36849, USA.
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9
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Ma Y, Li L, Awasthi MK, Tian H, Lu M, Megharaj M, Pan Y, He W. Time-course transcriptome analysis reveals the mechanisms of Burkholderia sp. adaptation to high phenol concentrations. Appl Microbiol Biotechnol 2020; 104:5873-5887. [PMID: 32415321 DOI: 10.1007/s00253-020-10672-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 04/28/2020] [Accepted: 05/05/2020] [Indexed: 01/02/2023]
Abstract
Microbial tolerance to phenolic pollutants is the key to their efficient biodegradation. However, the metabolic mechanisms that allow some microorganisms to adapt to high phenol concentrations remain unclear. In this study, to reveal the underlying mechanisms of how Burkholderia sp. adapt to high phenol concentrations, the strain's tolerance ability and time-course transcriptome in combination with cell phenotype were evaluated. Surprisingly, Burkholderia sp. still grew normally after a long adaptation to a relatively high phenol concentration (1500 mg/L) and exhibited some time-dependent changes compared to unstressed cells prior to the phenol addition. Time-course transcriptome analysis results revealed that the mechanism of adaptations to phenol was an evolutionary process that transitioned from tolerance to positive degradation through precise gene regulation at appropriate times. Specifically, basal stress gene expression was upregulated and contributed to phenol tolerance, which involved stress, DNA repair, membrane, efflux pump and antioxidant protein-coding genes, while a phenol degradation gene cluster was specifically induced. Interestingly, both the catechol and protocatechuate branches of the β-ketoadipate pathway contributed to the early stage of phenol degradation, but only the catechol branch was used in the late stage. In addition, pathways involving flagella, chemotaxis, ATP-binding cassette transporters and two-component systems were positively associated with strain survival under phenolic stress. This study provides the first insights into the specific response of Burkholderia sp. to high phenol stress and shows potential for application in remediation of polluted environments. KEY POINTS: • Shock, DNA repair and antioxidant-related genes contributed to phenol tolerance. • β-Ketoadipate pathway branches differed at different stages of phenol degradation. • Adaptation mechanisms transitioned from negative tolerance to positive degradation.
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Affiliation(s)
- Yinghui Ma
- Microbiology Institute of Shaanxi, Shaanxi Academy of Sciences, Xi'an, 710043, Shaanxi, PR China.,College of Natural Resources and Environment, Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Northwest A&F University, Yangling, 712100, Shaanxi, PR China
| | - Lijun Li
- Microbiology Institute of Shaanxi, Shaanxi Academy of Sciences, Xi'an, 710043, Shaanxi, PR China.
| | - Mukesh Kumar Awasthi
- College of Natural Resources and Environment, Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Northwest A&F University, Yangling, 712100, Shaanxi, PR China
| | - Haixia Tian
- College of Natural Resources and Environment, Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Northwest A&F University, Yangling, 712100, Shaanxi, PR China
| | - Meihuan Lu
- Microbiology Institute of Shaanxi, Shaanxi Academy of Sciences, Xi'an, 710043, Shaanxi, PR China
| | - Mallavarapu Megharaj
- Global Centre for Environmental Remediation, Faculty of Science, University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia
| | - Yalei Pan
- Shaanxi Collaborative Innovation Center of Chinese Medicine Resources Industrialization, Shaanxi University of Chinese Medicine, Xianyang, 712046, PR China
| | - Wenxiang He
- College of Natural Resources and Environment, Key Laboratory of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Northwest A&F University, Yangling, 712100, Shaanxi, PR China.
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10
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Wen Z, Ledesma‐Amaro R, Lu M, Jiang Y, Gao S, Jin M, Yang S. Combined evolutionary engineering and genetic manipulation improve low pH tolerance and butanol production in a synthetic microbial
Clostridium
community. Biotechnol Bioeng 2020; 117:2008-2022. [DOI: 10.1002/bit.27333] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/14/2020] [Accepted: 03/12/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Zhiqiang Wen
- School of Environmental and Biological Engineering, Nanjing University of Science & Technology Nanjing China
| | | | - Minrui Lu
- School of Environmental and Biological Engineering, Nanjing University of Science & Technology Nanjing China
| | - Yu Jiang
- Huzhou Center of Industrial Biotechnology, Shanghai Institutes of Biological SciencesChinese Academy of Sciences Zhejiang China
- Shanghai TaoYuSheng Biotechnology Co., Ltd. Shanghai China
| | - Shuliang Gao
- Zhejiang Huarui Biotechnology Co., Ltd. Zhejiang China
| | - Mingjie Jin
- School of Environmental and Biological Engineering, Nanjing University of Science & Technology Nanjing China
| | - Sheng Yang
- Huzhou Center of Industrial Biotechnology, Shanghai Institutes of Biological SciencesChinese Academy of Sciences Zhejiang China
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of Sciences Shanghai China
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11
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Yang Y, Lang N, Zhang L, Wu H, Jiang W, Gu Y. A novel regulatory pathway consisting of a two-component system and an ABC-type transporter contributes to butanol tolerance in Clostridium acetobutylicum. Appl Microbiol Biotechnol 2020; 104:5011-5023. [DOI: 10.1007/s00253-020-10555-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 02/23/2020] [Accepted: 03/16/2020] [Indexed: 11/28/2022]
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12
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Luo H, Zheng P, Bilal M, Xie F, Zeng Q, Zhu C, Yang R, Wang Z. Efficient bio-butanol production from lignocellulosic waste by elucidating the mechanisms of Clostridium acetobutylicum response to phenolic inhibitors. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 710:136399. [PMID: 31923698 DOI: 10.1016/j.scitotenv.2019.136399] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/24/2019] [Accepted: 12/27/2019] [Indexed: 05/12/2023]
Abstract
Lignocellulosic biomass is considered abundant renewable feedstock to constitute a green and environmentally friendly approach for biofuels (bio-butanol) production as an effective substitute for fossil resources. However, a variety of fermentable inhibitors can be generated in hydrolysates during the biomass pretreatment process. Among them, phenolics including phenolic acids and phenolic aldehydes are the most toxic inhibitors to solventogenic clostridia for bio-butanol production. This study elucidates the physiological mechanism of Clostridium acetobutylicum ATCC 824 response to phenolic inhibitors by the integration of kinetics and transcriptional analysis. Butanol fermentations were stressed by 0.4 g/L phenolic acids or 0.4 g/L phenolic aldehydes at 12 h at the beginning of solventogenesis. With post-stress for 12 h, butanol titer was 7.01 g/L in fermentation with phenolic acid stress, while only 5.82 g/L butanol was produced in the case of phenolic aldehydes stress. Reductions in the two fermentations were 27.6% and 40.0% in comparison with the control (without stress), indicated that phenolic aldehydes had a stronger inhibitory effect on solvents synthesis in C. acetobutylicum than phenolic acids. Additionally, the transcriptional analysis revealed that phenolics altered the gene expression profiles related to membrane transporters such as ATP-binding cassette (ABC)-transporter and phosphotransferase system (PTS), glycolysis, and heat shock proteins. The lower expression levels of PTS-related genes might result in reduced glucose consumption and finally inhibited solvents synthesis under phenolic aldehydes stress. Some genes encoding histidine kinase (CA_C0323, CA_C0903, and CA_C3319) were also affected by phenolics, which might inhibit sporulation. In conclusion, our results provide valuable guidance for the construction of robust strain to efficiently produce bio-butanol from lignocellulosic biomass.
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Affiliation(s)
- Hongzhen Luo
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China.
| | - Panli Zheng
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China
| | - Muhammad Bilal
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China
| | - Fang Xie
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China
| | - Qingwei Zeng
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China
| | - Chun Zhu
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China
| | - Rongling Yang
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China
| | - Zhaoyu Wang
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China
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13
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Liu J, Luo Y, Guo T, Tang C, Chai X, Zhao W, Bai J, Lin Q. Cost-effective pigment production by Monascus purpureus using rice straw hydrolysate as substrate in submerged fermentation. J Biosci Bioeng 2019; 129:229-236. [PMID: 31500988 DOI: 10.1016/j.jbiosc.2019.08.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 08/14/2019] [Indexed: 12/20/2022]
Abstract
Monascus pigments (MPs), the secondary metabolites produced by the fungal strains of Monascus spp., hold commercial importance in not only the food and meat industries, but also therapeutic, cosmetic, and textile industries. To reduce the cost of MPs production, the utilization of rice straw hydrolysate as a substrate in submerged fermentation was investigated. The atmospheric and room temperature plasma (ARTP) mutation system was employed to develop a mutant strain Monascus purpureus M630, with high total extracellular Monascus pigments (exMPs) production of 34.12 U/mL in submerged fermentation with glucose-based medium. The results revealed that M. purpureus M630 produces 8.61 U/mL and 20.86 U/mL of exMPs in rice straw hydrolysate alone or in combination with glucose fermentation medium, respectively. Furfural (Fur) and 5'-hydroxymethyl furfural (5'-HMF), produced during pretreatment and hydrolysis of rice straw; are generally inhibitory for microbial growth and fermentation. Our findings revealed that M. purpureus M630 develops the tolerance and adaptation mechanisms in response to 5'-HMF and Fur during growth and MPs biosynthesis in rice straw hydrolysate. In conclusion, we report that rice straw hydrolysate can serve as an efficient and low-cost substitute for the MP production through submerged fermentation by Monascus spp.
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Affiliation(s)
- Jun Liu
- Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, Hunan Key Laboratory of Processed Food for Special Medical Purpose, College of Food Science and Engineering, National Engineering Laboratory for Deep Process of Rice and Byproducts, Central South University of Forestry and Technology, Changsha, Hunan 410004, China; Key Laboratory of Staple Grain Processing, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Zhengzhou, Henan 450002, China
| | - Yunchuan Luo
- Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, Hunan Key Laboratory of Processed Food for Special Medical Purpose, College of Food Science and Engineering, National Engineering Laboratory for Deep Process of Rice and Byproducts, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
| | - Ting Guo
- Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, Hunan Key Laboratory of Processed Food for Special Medical Purpose, College of Food Science and Engineering, National Engineering Laboratory for Deep Process of Rice and Byproducts, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
| | - Chenglun Tang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 Puzhu South Road, Nanjing 211816, China
| | - Xueying Chai
- Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, Hunan Key Laboratory of Processed Food for Special Medical Purpose, College of Food Science and Engineering, National Engineering Laboratory for Deep Process of Rice and Byproducts, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
| | - Wen Zhao
- Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, Hunan Key Laboratory of Processed Food for Special Medical Purpose, College of Food Science and Engineering, National Engineering Laboratory for Deep Process of Rice and Byproducts, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
| | - Jie Bai
- Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, Hunan Key Laboratory of Processed Food for Special Medical Purpose, College of Food Science and Engineering, National Engineering Laboratory for Deep Process of Rice and Byproducts, Central South University of Forestry and Technology, Changsha, Hunan 410004, China
| | - Qinlu Lin
- Hunan Key Laboratory of Grain-Oil Deep Process and Quality Control, Hunan Key Laboratory of Processed Food for Special Medical Purpose, College of Food Science and Engineering, National Engineering Laboratory for Deep Process of Rice and Byproducts, Central South University of Forestry and Technology, Changsha, Hunan 410004, China.
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14
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Dos Santos Vieira CF, Maugeri Filho F, Maciel Filho R, Pinto Mariano A. Acetone-free biobutanol production: Past and recent advances in the Isopropanol-Butanol-Ethanol (IBE) fermentation. BIORESOURCE TECHNOLOGY 2019; 287:121425. [PMID: 31085056 DOI: 10.1016/j.biortech.2019.121425] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/02/2019] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
Production of butanol for fuel via the conventional Acetone-Butanol-Ethanol fermentation has been considered economically risky because of a potential oversupply of acetone. Alternatively, acetone is converted into isopropanol by specific solventogenic Clostridium species in the Isopropanol-Butanol-Ethanol (IBE) fermentation. This route, although less efficient, has been gaining attention because IBE mixtures are a potential fuel. The present work is dedicated to reviewing past and recent advances in microorganisms, feedstock, and fermentation equipment for IBE production. In our analysis we demonstrate the importance of novel engineered IBE-producing Clostridium strains and cell retention systems to decrease the staggering number of fermentation tanks required by IBE plants equipped with conventional technology. We also summarize the recent progress on recovery techniques integrated with fermentation, especially gas stripping. In addition, we assessed ongoing pilot-plant efforts that have been enabling IBE production from woody feedstock.
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Affiliation(s)
- Carla Ferreira Dos Santos Vieira
- Laboratory of Optimization, Design, and Advanced Control - Fermentation Division (LOPCA-Ferm), School of Chemical Engineering, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Francisco Maugeri Filho
- Bioprocess and Metabolic Engineering Laboratory (LEMeB), School of Food Engineering, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Rubens Maciel Filho
- Laboratory of Optimization, Design, and Advanced Control - Fermentation Division (LOPCA-Ferm), School of Chemical Engineering, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Adriano Pinto Mariano
- Laboratory of Optimization, Design, and Advanced Control - Fermentation Division (LOPCA-Ferm), School of Chemical Engineering, University of Campinas (UNICAMP), Campinas, SP, Brazil.
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15
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Okonkwo CC, Ujor V, Ezeji TC. Chromosomal integration of aldo-keto-reductase and short-chain dehydrogenase/reductase genes in Clostridium beijerinckii NCIMB 8052 enhanced tolerance to lignocellulose-derived microbial inhibitory compounds. Sci Rep 2019; 9:7634. [PMID: 31114009 PMCID: PMC6529405 DOI: 10.1038/s41598-019-44061-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 05/08/2019] [Indexed: 12/23/2022] Open
Abstract
In situ detoxification of lignocellulose-derived microbial inhibitory compounds is an economical strategy for the fermentation of lignocellulose-derived sugars to fuels and chemicals. In this study, we investigated homologous integration and constitutive expression of Cbei_3974 and Cbei_3904, which encode aldo-keto reductase and previously annotated short chain dehydrogenase/reductase, respectively, in Clostridium beijerinckii NCIMB 8052 (Cb), resulting in two strains: Cb_3974 and Cb_3904. Expression of Cbei_3974 led to 2-fold increase in furfural detoxification relative to Cb_3904 and Cb_wild type. Correspondingly, butanol production was up to 1.2-fold greater in furfural-challenged cultures of Cb_3974 relative to Cb_3904 and Cb_wild type. With 4-hydroxybezaldehyde and syringaldehyde supplementation, Cb_3974 showed up to 2.4-fold increase in butanol concentration when compared to Cb_3904 and Cb_wild type. Syringic and vanillic acids were considerably less deleterious to all three strains of Cb tested. Overall, Cb_3974 showed greater tolerance to furfural, 4-hydroxybezaldehyde, and syringaldehyde with improved capacity for butanol production. Hence, development of Cb_3974 represents a significant progress towards engineering solventogenic Clostridium species that are tolerant to lignocellulosic biomass hydrolysates as substrates for ABE fermentation.
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Affiliation(s)
- Christopher Chukwudi Okonkwo
- Department of Animal Sciences, The Ohio State University, and Ohio State Agricultural Research and Development Center (OARDC), 305 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH, 44691, USA
| | - Victor Ujor
- Bioenergy and Biological Waste Management Program, Agricultural Technical Institute, The Ohio State University, 1328 Dover Road, Wooster, OH, 44691, USA
| | - Thaddeus Chukwuemeka Ezeji
- Department of Animal Sciences, The Ohio State University, and Ohio State Agricultural Research and Development Center (OARDC), 305 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH, 44691, USA.
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16
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Improved n-Butanol Production from Clostridium cellulovorans by Integrated Metabolic and Evolutionary Engineering. Appl Environ Microbiol 2019; 85:AEM.02560-18. [PMID: 30658972 DOI: 10.1128/aem.02560-18] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/11/2019] [Indexed: 12/29/2022] Open
Abstract
Clostridium cellulovorans DSM 743B offers potential as a chassis strain for biomass refining by consolidated bioprocessing (CBP). However, its n-butanol production from lignocellulosic biomass has yet to be demonstrated. This study demonstrates the construction of a coenzyme A (CoA)-dependent acetone-butanol-ethanol (ABE) pathway in C. cellulovorans by introducing adhE1 and ctfA-ctfB-adc genes from Clostridium acetobutylicum ATCC 824, which enabled it to produce n-butanol using the abundant and low-cost agricultural waste of alkali-extracted, deshelled corn cobs (AECC) as the sole carbon source. Then, a novel adaptive laboratory evolution (ALE) approach was adapted to strengthen the n-butanol tolerance of C. cellulovorans to fully utilize its n-butanol output potential. To further improve n-butanol production, both metabolic engineering and evolutionary engineering were combined, using the evolved strain as a host for metabolic engineering. The n-butanol production from AECC of the engineered C. cellulovorans was increased 138-fold, from less than 0.025 g/liter to 3.47 g/liter. This method represents a milestone toward n-butanol production by CBP, using a single recombinant clostridium strain. The engineered strain offers a promising CBP-enabling microbial chassis for n-butanol fermentation from lignocellulose.IMPORTANCE Due to a lack of genetic tools, Clostridium cellulovorans DSM 743B has not been comprehensively explored as a putative strain platform for n-butanol production by consolidated bioprocessing (CBP). Based on the previous study of genetic tools, strain engineering of C. cellulovorans for the development of a CBP-enabling microbial chassis was demonstrated in this study. Metabolic engineering and evolutionary engineering were integrated to improve the n-butanol production of C. cellulovorans from the low-cost renewable agricultural waste of alkali-extracted, deshelled corn cobs (AECC). The n-butanol production from AECC was increased 138-fold, from less than 0.025 g/liter to 3.47 g/liter, which represents the highest titer of n-butanol produced using a single recombinant clostridium strain by CBP reported to date. This engineered strain serves as a promising chassis for n-butanol production from lignocellulose by CBP.
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17
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Luo H, Zheng P, Xie F, Yang R, Liu L, Han S, Zhao Y, Bilal M. Co-production of solvents and organic acids in butanol fermentation by Clostridium acetobutylicum in the presence of lignin-derived phenolics. RSC Adv 2019; 9:6919-6927. [PMID: 35518483 PMCID: PMC9061099 DOI: 10.1039/c9ra00325h] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 02/21/2019] [Indexed: 12/16/2022] Open
Abstract
Co-production of solvents (butanol, acetone, and ethanol) and organic acids (butyrate and acetate) by Clostridium acetobutylicum using lignocellulosic biomass as a substrate could further enlarge the application scope of butanol fermentation. This is mainly because solvents and organic acids could be used for production of fine chemicals such as butyl butyrate, butyl oleate, etc. However, many phenolic fermentation inhibitors are formed during the pretreatment process because of lignin degradation. The present study investigated the effects of five typical lignin-derived phenolics on the biosynthesis of solvents and organic acids in C. acetobutylicum ATCC 824. Results obtained in 100 mL anaerobic bottles indicated that butanol concentration was enhanced from 10.29 g L−1 to 11.36 g L−1 by the addition of 0.1 g L−1 vanillin. Subsequently, a pH-control strategy was proposed in a 5 L anaerobic fermenter to alleviate the “acid crash” phenomenon and improve butanol fermentation performance, simultaneously. Notably, organic acid concentration was enhanced from 6.38 g L−1 (control) to a high level of 9.21–12.57 g L−1 with vanillin or/and vanillic acid addition (0.2 g L−1) under the pH-control strategy. Furthermore, the butyrate/butanol ratio reached the highest level of 0.80 g g−1 with vanillin/vanillic acid co-addition, and solvent concentration reached 13.85 g L−1, a comparable level to the control (13.69 g L−1). The effectiveness and robustness of the strategy for solvent and organic acid co-production was also verified under five typical phenolic environments. In conclusion, these results suggest that the proposed process strategy would potentially promote butanol fermentative products from renewable biomass. Lignin-derived phenolics enhance solvent and organic acid biosynthesis in butanol fermentation by Clostridium acetobutylicum ATCC 824.![]()
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Affiliation(s)
- Hongzhen Luo
- School of Life Science and Food Engineering
- Huaiyin Institute of Technology
- Huaian 223003
- China
| | - Panli Zheng
- School of Life Science and Food Engineering
- Huaiyin Institute of Technology
- Huaian 223003
- China
| | - Fang Xie
- School of Life Science and Food Engineering
- Huaiyin Institute of Technology
- Huaian 223003
- China
| | - Rongling Yang
- School of Life Science and Food Engineering
- Huaiyin Institute of Technology
- Huaian 223003
- China
| | - Lina Liu
- School of Life Science and Food Engineering
- Huaiyin Institute of Technology
- Huaian 223003
- China
| | - Shuo Han
- Department of Chemistry
- Missouri University of Science and Technology
- Rolla
- USA
| | - Yuping Zhao
- School of Life Science and Food Engineering
- Huaiyin Institute of Technology
- Huaian 223003
- China
| | - Muhammad Bilal
- School of Life Science and Food Engineering
- Huaiyin Institute of Technology
- Huaian 223003
- China
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18
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Liao Z, Guo X, Hu J, Suo Y, Fu H, Wang J. The significance of proline on lignocellulose-derived inhibitors tolerance in Clostridium acetobutylicum ATCC 824. BIORESOURCE TECHNOLOGY 2019; 272:561-569. [PMID: 30396113 DOI: 10.1016/j.biortech.2018.10.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 10/15/2018] [Accepted: 10/16/2018] [Indexed: 06/08/2023]
Abstract
When lignocellulosic biomass was used for acetone-butanol-ethanol (ABE) fermentation, several lignocellulose-derived inhibitors, which are toxic to Clostridium acetobutylicum, were generated during acid hydrolysis process and seriously hindered the industrialization of lignocellulosic butanol. In this study, an engineered strain 824(proABC) with significantly improved tolerance to multiple lignocellulose-derived inhibitors (formic acid and phenolic compounds) was constructed by strengthening the proline biosynthesis. The engineered strain exhibited more effective synthesis ability of proline and scavenging ability of reactive oxygen species (ROS). Consequently, the butanol produced by 824(proABC) was 1-, 2.4- or 3.4-fold higher than that of the wild type strain when using the undetoxified hydrolysate of soybean straw, rice straw or corn straw as the substrate, respectively. Therefore, enhancing the proline biosynthesis can be used as an effective strategy to improve the tolerance of C. acetobutylicum to multiple lignocellulose-derived inhibitors, and 824(proABC) has great potential to produce butanol from undetoxified lignocellulosic hydrolysates.
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Affiliation(s)
- Zhengping Liao
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Xiaolong Guo
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Jialei Hu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Yukai Suo
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Hongxin Fu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China.
| | - Jufang Wang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China; State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China.
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19
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The draft genome sequence of Clostridium sp. strain LJ4 with high furan and phenolic derivates' tolerances occurring from lignocellulosic hydrolysates. 3 Biotech 2018; 8:406. [PMID: 30237953 DOI: 10.1007/s13205-018-1430-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 09/10/2018] [Indexed: 10/28/2022] Open
Abstract
The genome of a wild-type solventogenic Clostridium sp. strain LJ4 that could directly convert undetoxified lignocellulosic hydrolysate to butanol and tolerate high concentration of furan and phenolic derivates occurring in the lignocellulosic hydrolysate is described. 16S rDNA gene sequencing and analysis indicated that it is closely related to Clostridium acetobutylicum. The genome size of strain LJ4 is 3.90 Mp, which has a G + C content of 30.72% and encodes 2711 proteins. It also has one 0.19 Mp plasmid with 181 predicted encoding proteins. Alcohol dehydrogenases (ADs) and a nicotinamide adenine dinucleotide phosphate (NADPH)-dependent flavin mononucleotide (FMN) reductase were identified, which may play key roles in inhibitors' resistance in lignocellulosic hydrolysate.
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20
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Solvent production from xylose. Appl Microbiol Biotechnol 2018; 102:8707-8715. [PMID: 30109398 DOI: 10.1007/s00253-018-9254-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/17/2018] [Accepted: 07/18/2018] [Indexed: 02/04/2023]
Abstract
Xylose is the second most abundant sugar derived from lignocellulose; it is considered less desirable than glucose for fermentation, and strategies that specifically increase xylose utilization in wild type or engineered cells are goals for biofuel production. Issues arise with xylose utilization because of carbohydrate catabolite repression, which is the preferential utilization of glucose relative to xylose in fermentations with both pure and mixed cultures. Taken together the low substrate utilization rates and solvent yields with xylose compared to glucose, many industrial fermentations ignore the xylolytic portion of the reaction in lieu of methods to maintain high glucose. This is shortsighted given the massive potential for xylose generation from a number of sustainable biomass feedstocks, based on utilization of the hemicellulose fraction(s) that enter pretreatment. A number of strategies have been developed in recent years to address xylose utilization and solvent production from xylose in systems with just xylose, or in systems with mixtures of glucose plus xylose, which are more typical of pretreated lignocellulose. The approaches vary in terms of complexity, stability, and ease of introduction to existing fermentation infrastructure (i.e., so-called drop-in fermentation strategies). Some approaches can be considered traditional engineering approaches (e.g., change the reaction conditions), while others are more subtle cellular approaches to eliminate the impacts of catabolite repression. Finally, genetic engineering has been used to increase xylose utilization, although this can be considered a relatively nascent approach compared to manipulations completed to date for glucose utilization.
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