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Xiao Y, Dong S, Liu YJ, You C, Feng Y, Cui Q. Key roles of β-glucosidase BglA for the catabolism of both laminaribiose and cellobiose in the lignocellulolytic bacterium Clostridium thermocellum. Int J Biol Macromol 2023; 250:126226. [PMID: 37558019 DOI: 10.1016/j.ijbiomac.2023.126226] [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: 04/05/2023] [Revised: 07/31/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023]
Abstract
The thermophilic bacterium Clostridium thermocellum efficiently degrades polysaccharides into oligosaccharides. The metabolism of β-1,4-linked cello-oligosaccharides is initiated by three enzymes, i.e., the cellodextrin phosphorylase (Cdp), the cellobiose phosphorylase (Cbp), and the β-glucosidase A (BglA), in C. thermocellum. In comparison, how the oligosaccharides containing other kinds of linkage are utilized is rarely understood. In this study, we found that BglA could hydrolyze the β-1,3-disaccharide laminaribiose with much higher activity than that against the β-1,4-disaccharide cellobiose. The structural basis of the substrate specificity was analyzed by crystal structure determination and molecular docking. Genetic deletions of BglA and Cbp, respectively, and enzymatic analysis of cell extracts demonstrated that BglA is the key enzyme responsible for laminaribiose metabolism. Furthermore, the deletion of BglA can suppress the expression of Cbp and the deletion of Cbp can up-regulate the expression of BglA, indicating that BglA and Cbp have cross-regulation and BglA is also critical for cellobiose metabolism. These insights pave the way for both a fundamental understanding of metabolism and regulation in C. thermocellum and emphasize the importance of the degradation and utilization of polysaccharides containing β-1,3-linked glycosidic bonds in lignocellulose biorefinery.
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Affiliation(s)
- Yan Xiao
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Sheng Dong
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Ya-Jun Liu
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Chun You
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China.
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2
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Song Y, Wang Z, Long Y, Mao Y, Jiang F, Lu Y. 2-Alkyl-anthraquinones inhibit Candida albicans biofilm via inhibiting the formation of matrix and hyphae. Res Microbiol 2022; 173:103955. [PMID: 35550403 DOI: 10.1016/j.resmic.2022.103955] [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: 12/07/2021] [Revised: 05/01/2022] [Accepted: 05/02/2022] [Indexed: 10/18/2022]
Abstract
Candida albicans can form biofilm on biotic and abiotic surfaces of medical implants to cause superficial and systemic infections under specific condition. The formation of hyphae and matrix of C. albicans are considered as probable virulence factors. We assessed the inhibitory activities of 26 anthraquinones against C. albicans biofilm formation, which were substituted by different functional groups including hydroxyl groups, amino groups, carboxyl groups, alkyl groups, and glycoside groups at C1- or C2-position. Among them, anthraquinones without substituents at other positions but only an alkyl group attached to C2-position, namely 2-alkyl-anthraquinones were determined to have significant anti-biofilm activities. Furthermore, 2-ethylanthraquinone can significantly affect genes related to extracellular matrix (PMT6 and IFD6), and hyphal formation (HWP1, ECE1 and EFG1), leading to the disrupted formation of biofilm, by detail transcriptomics analysis. We believed that 2-ethylanthraquinone could inspire more discoveries of anti-biofilm agents against C. albicans.
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Affiliation(s)
- Yuanyuan Song
- State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009, China
| | - Ziqi Wang
- State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009, China
| | - Yijing Long
- State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009, China
| | - Yang Mao
- State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009, China
| | - Feng Jiang
- State Key Laboratory of Natural Medicines, School of Engineering, China Pharmaceutical University, Nanjing, 210009, China.
| | - Yuanyuan Lu
- State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009, China.
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3
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Gardner JG, Schreier HJ. Unifying themes and distinct features of carbon and nitrogen assimilation by polysaccharide-degrading bacteria: a summary of four model systems. Appl Microbiol Biotechnol 2021; 105:8109-8127. [PMID: 34611726 DOI: 10.1007/s00253-021-11614-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 11/24/2022]
Abstract
Our current understanding of enzymatic polysaccharide degradation has come from a huge number of in vitro studies with purified enzymes. While this vast body of work has been invaluable in identifying and characterizing novel mechanisms of action and engineering desirable traits into these enzymes, a comprehensive picture of how these enzymes work as part of a native in vivo system is less clear. Recently, several model bacteria have emerged with genetic systems that allow for a more nuanced study of carbohydrate active enzymes (CAZymes) and how their activity affects bacterial carbon metabolism. With these bacterial model systems, it is now possible to not only study a single nutrient system in isolation (i.e., carbohydrate degradation and carbon metabolism), but also how multiple systems are integrated. Given that most environmental polysaccharides are carbon rich but nitrogen poor (e.g., lignocellulose), the interplay between carbon and nitrogen metabolism in polysaccharide-degrading bacteria can now be studied in a physiologically relevant manner. Therefore, in this review, we have summarized what has been experimentally determined for CAZyme regulation, production, and export in relation to nitrogen metabolism for two Gram-positive (Caldicellulosiruptor bescii and Clostridium thermocellum) and two Gram-negative (Bacteroides thetaiotaomicron and Cellvibrio japonicus) polysaccharide-degrading bacteria. By comparing and contrasting these four bacteria, we have highlighted the shared and unique features of each, with a focus on in vivo studies, in regard to carbon and nitrogen assimilation. We conclude with what we believe are two important questions that can act as guideposts for future work to better understand the integration of carbon and nitrogen metabolism in polysaccharide-degrading bacteria. KEY POINTS: • Regardless of CAZyme deployment system, the generation of a local pool of oligosaccharides is a common strategy among Gram-negative and Gram-positive polysaccharide degraders as a means to maximally recoup the energy expenditure of CAZyme production and export. • Due to the nitrogen deficiency of insoluble polysaccharide-containing substrates, Gram-negative and Gram-positive polysaccharide degraders have a diverse set of strategies for supplementation and assimilation. • Future work needs to precisely characterize the energetic expenditures of CAZyme deployment and bolster our understanding of how carbon and nitrogen metabolism are integrated in both Gram-negative and Gram-positive polysaccharide-degrading bacteria, as both of these will significantly influence a given bacterium's suitability for biotechnology applications.
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Affiliation(s)
- Jeffrey G Gardner
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA.
| | - Harold J Schreier
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA.,Department of Marine Biotechnology, Institute of Marine and Environmental Technology, University of Maryland, Baltimore County, Baltimore, MD, USA
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4
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Arizzi M, Morra S, Gilardi G, Pugliese M, Gullino ML, Valetti F. Improving sustainable hydrogen production from green waste: [FeFe]-hydrogenases quantitative gene expression RT-qPCR analysis in presence of autochthonous consortia. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:182. [PMID: 34530890 PMCID: PMC8444407 DOI: 10.1186/s13068-021-02028-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 08/28/2021] [Indexed: 06/01/2023]
Abstract
BACKGROUND Bio-hydrogen production via dark fermentation of low-value waste is a potent and simple mean of recovering energy, maximising the harvesting of reducing equivalents to produce the cleanest fuel amongst renewables. Following several position papers from companies and public bodies, the hydrogen economy is regaining interest, especially in combination with circular economy and the environmental benefits of short local supply chains, aiming at zero net emission of greenhouse gases (GHG). The biomasses attracting the largest interest are agricultural and urban green wastes (pruning of trees, collected leaves, grass clippings from public parks and boulevards), which are usually employed in compost production, with some concerns over the GHG emission during the process. Here, an alternative application of green wastes, low-value compost and intermediate products (partially composted but unsuitable for completing the process) is studied, pointing at the autochthonous microbial consortium as an already selected source of implementation for biomass degradation and hydrogen production. The biocatalysts investigated as mainly relevant for hydrogen production were the [FeFe]-hydrogenases expressed in Clostridia, given their very high turnover rates. RESULTS Bio-hydrogen accumulation was related to the modulation of gene expression of multiple [FeFe]-hydrogenases from two strains (Clostridium beijerinckii AM2 and Clostridium tyrobutyricum AM6) isolated from the same waste. Reverse Transcriptase quantitative PCR (RT-qPCR) was applied over a period of 288 h and the RT-qPCR results showed that C. beijerinckii AM2 prevailed over C. tyrobutyricum AM6 and a high expression modulation of the 6 different [FeFe]-hydrogenase genes of C. beijerinckii in the first 23 h was observed, sustaining cumulative hydrogen production of 0.6 to 1.2 ml H2/g VS (volatile solids). These results are promising in terms of hydrogen yields, given that no pre-treatment was applied, and suggested a complex cellular regulation, linking the performance of dark fermentation with key functional genes involved in bio-H2 production in presence of the autochthonous consortium, with different roles, time, and mode of expression of the involved hydrogenases. CONCLUSIONS An applicative outcome of the hydrogenases genes quantitative expression analysis can be foreseen in optimising (on the basis of the acquired functional data) hydrogen production from a nutrient-poor green waste and/or low added value compost, in a perspective of circular bioeconomy.
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Affiliation(s)
- M Arizzi
- Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123, Torino, Italy
- Acea Engineering Laboratories Research Innovation SpA, Roma, Italy
| | - S Morra
- Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123, Torino, Italy
- Faculty of Engineering, University of Nottingham, Nottingham, UK
| | - G Gilardi
- Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123, Torino, Italy
| | - M Pugliese
- Centre of Competence for Innovation in Agro-Environmental Field (Agroinnova) and DiSAFA, University of Torino, Largo Paolo Braccini 2, 10095, Grugliasco, TO, Italy
- AgriNewTech Srl, Via Livorno 60, 10140, Torino, Italy
| | - M L Gullino
- Centre of Competence for Innovation in Agro-Environmental Field (Agroinnova) and DiSAFA, University of Torino, Largo Paolo Braccini 2, 10095, Grugliasco, TO, Italy
- AgriNewTech Srl, Via Livorno 60, 10140, Torino, Italy
| | - F Valetti
- Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123, Torino, Italy.
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Utilization of Monosaccharides by Hungateiclostridium thermocellum ATCC 27405 through Adaptive Evolution. Microorganisms 2021; 9:microorganisms9071445. [PMID: 34361881 PMCID: PMC8303734 DOI: 10.3390/microorganisms9071445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 06/30/2021] [Accepted: 07/02/2021] [Indexed: 12/13/2022] Open
Abstract
Hungateiclostridium thermocellum ATCC 27405 is a promising bacterium for consolidated bioprocessing with a robust ability to degrade lignocellulosic biomass through a multienzyme cellulosomal complex. The bacterium uses the released cellodextrins, glucose polymers of different lengths, as its primary carbon source and energy. In contrast, the bacterium exhibits poor growth on monosaccharides such as fructose and glucose. This phenomenon raises many important questions concerning its glycolytic pathways and sugar transport systems. Until now, the detailed mechanisms of H. thermocellum adaptation to growth on hexose sugars have been relatively poorly explored. In this study, adaptive laboratory evolution was applied to train the bacterium in hexose sugars-based media, and genome resequencing was used to detect the genes that got mutated during adaptation period. RNA-seq data of the first culture growing on either fructose or glucose revealed that several glycolytic genes in the Embden–Mayerhof–Parnas pathway were expressed at lower levels in these cells than in cellobiose-grown cells. After seven consecutive transfer events on fructose and glucose (~42 generations for fructose-adapted cells and ~40 generations for glucose-adapted cells), several genes in the EMP glycolysis of the evolved strains increased the levels of mRNA expression, accompanied by a faster growth, a greater biomass yield, a higher ethanol titer than those in their parent strains. Genomic screening also revealed several mutation events in the genomes of the evolved strains, especially in those responsible for sugar transport and central carbon metabolism. Consequently, these genes could be applied as potential targets for further metabolic engineering to improve this bacterium for bio-industrial usage.
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Cloning and characterization of a L-lactate dehydrogenase gene from Ruminococcaceae bacterium CPB6. World J Microbiol Biotechnol 2020; 36:182. [PMID: 33170386 DOI: 10.1007/s11274-020-02958-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 11/03/2020] [Indexed: 10/23/2022]
Abstract
Lactate are proved to be attractive electron donor for the production of n-caproic acid (CA) that is a high value-added fuel precursor and chemical feedstock, but little is known about molecular mechanism of lactate transformation. In the present study, the gene for L-lactate dehydrogenase (LDH, EC.1.1.1.27) from a Ruminococcaceae strain CPB6 was cloned and expressed in Escherichia coli BL21 (DE3) with plasmid pET28a. The recombinant LDH exhibited molecular weight of 36-38 kDa in SDS-PAGE. The purified LDH was found to have the maximal oxidation activity of 29.6 U/mg from lactate to pyruvate at pH 6.5, and the maximal reduction activity of 10.4 U/mg from pyruvate to lactate at pH 8.5, respectively. Strikingly, its oxidative activity predominates over reductive activity, leading to a 17-fold increase for the utilization of lactate in E. coli/pET28a-LDH than E. coli/pET28a. The CPB6 LDH gene encodes a 315 amino acid protein sharing 42.19% similarity with Clostridium beijerinckii LDH, and lower similarity with LDHs of other organisms. Significant difference were observed between the CPB6 LDH and C. beijerinckii and C. acetobutylicum LDH in the predicted tertiary structure and active center. Further, X-ray crystal structure analysis need to be performed to verify the specific active center of the CPB6 LDH and its role in the conversion of lactate into CA.
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Transcriptomic analysis of a Clostridium thermocellum strain engineered to utilize xylose: responses to xylose versus cellobiose feeding. Sci Rep 2020; 10:14517. [PMID: 32884054 PMCID: PMC7471329 DOI: 10.1038/s41598-020-71428-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 08/10/2020] [Indexed: 12/20/2022] Open
Abstract
Clostridium (Ruminiclostridium) thermocellum is recognized for its ability to ferment cellulosic biomass directly, but it cannot naturally grow on xylose. Recently, C. thermocellum (KJC335) was engineered to utilize xylose through expressing a heterologous xylose catabolizing pathway. Here, we compared KJC335′s transcriptomic responses to xylose versus cellobiose as the primary carbon source and assessed how the bacteria adapted to utilize xylose. Our analyses revealed 417 differentially expressed genes (DEGs) with log2 fold change (FC) >|1| and 106 highly DEGs (log2 FC >|2|). Among the DEGs, two putative sugar transporters, cbpC and cbpD, were up-regulated, suggesting their contribution to xylose transport and assimilation. Moreover, the up-regulation of specific transketolase genes (tktAB) suggests the importance of this enzyme for xylose metabolism. Results also showed remarkable up-regulation of chemotaxis and motility associated genes responding to xylose feeding, as well as widely varying gene expression in those encoding cellulosomal enzymes. For the down-regulated genes, several were categorized in gene ontology terms oxidation–reduction processes, ATP binding and ATPase activity, and integral components of the membrane. This study informs potentially critical, enabling mechanisms to realize the conceptually attractive Next-Generation Consolidated BioProcessing approach where a single species is sufficient for the co-fermentation of cellulose and hemicellulose.
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Wei Z, Chen C, Liu YJ, Dong S, Li J, Qi K, Liu S, Ding X, Ortiz de Ora L, Muñoz-Gutiérrez I, Li Y, Yao H, Lamed R, Bayer EA, Cui Q, Feng Y. Alternative σI/anti-σI factors represent a unique form of bacterial σ/anti-σ complex. Nucleic Acids Res 2019; 47:5988-5997. [PMID: 31106374 PMCID: PMC6582324 DOI: 10.1093/nar/gkz355] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/21/2019] [Accepted: 04/26/2019] [Indexed: 12/18/2022] Open
Abstract
The σ70 family alternative σI factors and their cognate anti-σI factors are widespread in Clostridia and Bacilli and play a role in heat stress response, virulence, and polysaccharide sensing. Multiple σI/anti-σI factors exist in some lignocellulolytic clostridial species, specifically for regulation of components of a multienzyme complex, termed the cellulosome. The σI and anti-σI factors are unique, because the C-terminal domain of σI (SigIC) and the N-terminal inhibitory domain of anti-σI (RsgIN) lack homology to known proteins. Here, we report structure and interaction studies of a pair of σI and anti-σI factors, SigI1 and RsgI1, from the cellulosome-producing bacterium, Clostridium thermocellum. In contrast to other known anti-σ factors that have N-terminal helical structures, RsgIN has a β-barrel structure. Unlike other anti-σ factors that bind both σ2 and σ4 domains of the σ factors, RsgIN binds SigIC specifically. Structural analysis showed that SigIC contains a positively charged surface region that recognizes the promoter -35 region, and the synergistic interactions among multiple interfacial residues result in the specificity displayed by different σI/anti-σI pairs. We suggest that the σI/anti-σI factors represent a distinctive mode of σ/anti-σ complex formation, which provides the structural basis for understanding the molecular mechanism of the intricate σI/anti-σI system.
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Affiliation(s)
- Zhen Wei
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chao Chen
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Ya-Jun Liu
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Sheng Dong
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Jie Li
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kuan Qi
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shiyue Liu
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoke Ding
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Lizett Ortiz de Ora
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Iván Muñoz-Gutiérrez
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Yifei Li
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Hongwei Yao
- High-Field Nuclear Magnetic Resonance Center, Xiamen University, 422 South Siming Road, Xiamen 361005, China
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- To whom correspondence should be addressed. Tel: +86 532 80662706; Fax: +86 532 80662707;
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Okonkwo O, Escudie R, Bernet N, Mangayil R, Lakaniemi AM, Trably E. Bioaugmentation enhances dark fermentative hydrogen production in cultures exposed to short-term temperature fluctuations. Appl Microbiol Biotechnol 2019; 104:439-449. [PMID: 31754763 PMCID: PMC6942602 DOI: 10.1007/s00253-019-10203-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/27/2019] [Accepted: 10/19/2019] [Indexed: 01/20/2023]
Abstract
Hydrogen-producing mixed cultures were subjected to a 48-h downward or upward temperature fluctuation from 55 to 35 or 75 °C. Hydrogen production was monitored during the fluctuations and for three consecutive batch cultivations at 55 °C to evaluate the impact of temperature fluctuations and bioaugmentation with synthetic mixed culture of known H2 producers either during or after the fluctuation. Without augmentation, H2 production was significantly reduced during the downward temperature fluctuation and no H2 was produced during the upward fluctuation. H2 production improved significantly during temperature fluctuation when bioaugmentation was applied to cultures exposed to downward or upward temperatures. However, when bioaugmentation was applied after the fluctuation, i.e., when the cultures were returned to 55 °C, the H2 yields obtained were between 1.6 and 5% higher than when bioaugmentation was applied during the fluctuation. Thus, the results indicate the usefulness of bioaugmentation in process recovery, especially if bioaugmentation time is optimised.
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Affiliation(s)
| | | | | | - Rahul Mangayil
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
| | - Aino-Maija Lakaniemi
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
| | - Eric Trably
- LBE, Univ Montpellier, INRA, Narbonne, France
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10
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Wang F, Wang M, Zhao Q, Niu K, Liu S, He D, Liu Y, Xu S, Fang X. Exploring the Relationship Between Clostridium thermocellum JN4 and Thermoanaerobacterium thermosaccharolyticum GD17. Front Microbiol 2019; 10:2035. [PMID: 31551972 PMCID: PMC6746925 DOI: 10.3389/fmicb.2019.02035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/19/2019] [Indexed: 11/13/2022] Open
Abstract
Characterizing and engineering microbial communities for lignocellulosic biofuel production has received widespread attention. Previous research has established that Clostridium thermocellum JN4 and Thermoanaerobacterium thermosaccharolyticum GD17 coculture significantly improves overall cellulosic biofuel production efficiency. Here, we investigated this interaction and revealed the mechanism underlying the improved efficiency observed. In contrast to the previously reported mutualistic relationship, a harmful effect toward C. thermocellum JN4 was observed in these microbial consortia. Although T. thermosaccharolyticum GD17 relieves the carbon catabolite repression of C. thermocellum JN4 regarding obtaining more cellobiose or glucose released from lignocellulose, T. thermosaccharolyticum GD17 significantly hampers the growth of C. thermocellum JN4 in coculture. The increased formation of end products is due to the strong competitive metabolic advantage of T. thermosaccharolyticum GD17 over C. thermocellum JN4 in the conversion of glucose or cellobiose into final products. The possibility of controlling and rebalancing these microbial consortia to modulate cellulose degradation was achieved by adding T. thermosaccharolyticum GD17 stimulants into the system. As cellulolytic bacteria are usually at a metabolic disadvantage, these discoveries may apply to a large proportion of cellulosic biofuel-producing microbial consortia. These findings provide a reference for engineering efficient and modular microbial consortia for modulating cellulosic conversion.
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Affiliation(s)
- Fangzhong Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.,Center for Biosafety Research and Strategy, Tianjin University, Tianjin, China
| | - Mingyu Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Qi Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Kangle Niu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Shasha Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Didi He
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yan Liu
- College of Life Science, Qufu Normal University, Qufu, China
| | - Shiping Xu
- School of Environmental Science and Engineering, Shandong University, Qingdao, China
| | - Xu Fang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
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11
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Rational development of transformation in Clostridium thermocellum ATCC 27405 via complete methylome analysis and evasion of native restriction-modification systems. J Ind Microbiol Biotechnol 2019; 46:1435-1443. [PMID: 31342224 PMCID: PMC6791906 DOI: 10.1007/s10295-019-02218-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 07/11/2019] [Indexed: 12/13/2022]
Abstract
A major barrier to both metabolic engineering and fundamental biological studies is the lack of genetic tools in most microorganisms. One example is Clostridium thermocellum ATCC 27405T, where genetic tools are not available to help validate decades of hypotheses. A significant barrier to DNA transformation is restriction–modification systems, which defend against foreign DNA methylated differently than the host. To determine the active restriction–modification systems in this strain, we performed complete methylome analysis via single-molecule, real-time sequencing to detect 6-methyladenine and 4-methylcytosine and the rarely used whole-genome bisulfite sequencing to detect 5-methylcytosine. Multiple active systems were identified, and corresponding DNA methyltransferases were expressed from the Escherichia coli chromosome to mimic the C. thermocellum methylome. Plasmid methylation was experimentally validated and successfully electroporated into C. thermocellum ATCC 27405. This combined approach enabled genetic modification of the C. thermocellum-type strain and acts as a blueprint for transformation of other non-model microorganisms.
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Neumann AP, Weimer PJ, Suen G. A global analysis of gene expression in Fibrobacter succinogenes S85 grown on cellulose and soluble sugars at different growth rates. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:295. [PMID: 30386432 PMCID: PMC6204037 DOI: 10.1186/s13068-018-1290-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 10/15/2018] [Indexed: 05/04/2023]
Abstract
BACKGROUND Cellulose is the most abundant biological polymer on earth, making it an attractive substrate for the production of next-generation biofuels and commodity chemicals. However, the economics of cellulose utilization are currently unfavorable due to a lack of efficient methods for its hydrolysis. Fibrobacter succinogenes strain S85, originally isolated from the bovine rumen, is among the most actively cellulolytic mesophilic bacteria known, producing succinate as its major fermentation product. In this study, we examined the transcriptome of F. succinogenes S85 grown in continuous culture at several dilution rates on cellulose, cellobiose, or glucose to gain a system-level understanding of cellulose degradation by this bacterium. RESULTS Several patterns of gene expression were observed for the major cellulases produced by F. succinogenes S85. A large proportion of cellulase genes were constitutively expressed, including the gene encoding for Cel51A, the major cellulose-binding endoglucanase produced by this bacterium. Moreover, other cellulase genes displayed elevated expression during growth on cellulose relative to growth on soluble sugars. Growth rate had a strong effect on global gene expression, particularly with regard to genes predicted to encode carbohydrate-binding modules and glycoside hydrolases implicated in hemicellulose degradation. Expression of hemicellulase genes was tightly regulated, with these genes displaying elevated expression only during slow growth on soluble sugars. Clear differences in gene expression were also observed between adherent and planktonic populations within continuous cultures growing on cellulose. CONCLUSIONS This work emphasizes the complexity of the fiber-degrading system utilized by F. succinogenes S85, and reinforces the complementary role of hemicellulases for accessing cellulose by these bacteria. We report for the first time evidence of global differences in gene expression between adherent and planktonic populations of an anaerobic bacterium growing on cellulose at steady state during continuous cultivation. Finally, our results also highlight the importance of controlling for growth rate in investigations of gene expression.
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Affiliation(s)
- Anthony P. Neumann
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI USA
| | - Paul J. Weimer
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI USA
- Agricultural Research Service, United States Department of Agriculture, Madison, WI USA
| | - Garret Suen
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI USA
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Yoav S, Barak Y, Shamshoum M, Borovok I, Lamed R, Dassa B, Hadar Y, Morag E, Bayer EA. How does cellulosome composition influence deconstruction of lignocellulosic substrates in Clostridium ( Ruminiclostridium) thermocellum DSM 1313? BIOTECHNOLOGY FOR BIOFUELS 2017; 10:222. [PMID: 28932263 PMCID: PMC5604425 DOI: 10.1186/s13068-017-0909-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 09/07/2017] [Indexed: 05/23/2023]
Abstract
BACKGROUND Bioethanol production processes involve enzymatic hydrolysis of pretreated lignocellulosic biomass into fermentable sugars. Due to the relatively high cost of enzyme production, the development of potent and cost-effective cellulolytic cocktails is critical for increasing the cost-effectiveness of bioethanol production. In this context, the multi-protein cellulolytic complex of Clostridium (Ruminiclostridium) thermocellum, the cellulosome, was studied here. C. thermocellum is known to assemble cellulosomes of various subunit (enzyme) compositions, in response to the available carbon source. In the current study, different carbon sources were used, and their influence on both cellulosomal composition and the resultant activity was investigated. RESULTS Glucose, cellobiose, microcrystalline cellulose, alkaline-pretreated switchgrass, alkaline-pretreated corn stover, and dilute acid-pretreated corn stover were used as sole carbon sources in the growth media of C. thermocellum strain DSM 1313. The purified cellulosomes were compared for their activity on selected cellulosic substrates. Interestingly, cellulosomes derived from cells grown on lignocellulosic biomass showed no advantage in hydrolyzing the original carbon source used for their production. Instead, microcrystalline cellulose- and glucose-derived cellulosomes were equal or superior in their capacity to deconstruct lignocellulosic biomass. Mass spectrometry analysis revealed differential composition of catalytic and structural subunits (scaffoldins) in the different cellulosome samples. The most abundant catalytic subunits in all cellulosome types include Cel48S, Cel9K, Cel9Q, Cel9R, and Cel5G. Microcrystalline cellulose- and glucose-derived cellulosome samples showed higher endoglucanase-to-exoglucanase ratios and higher catalytic subunit-per-scaffoldin ratios compared to lignocellulose-derived cellulosome types. CONCLUSION The results reported here highlight the finding that cellulosomes derived from cells grown on glucose and microcrystalline cellulose are more efficient in their action on cellulosic substrates than other cellulosome preparations. These results should be considered in the future development of C. thermocellum-based cellulolytic cocktails, designer cellulosomes, or engineering of improved strains for deconstruction of lignocellulosic biomass.
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Affiliation(s)
- Shahar Yoav
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food and Environment, The Advanced School for Environmental Studies, The Hebrew University of Jerusalem, 76100 Rehovot, Israel
- Designer Energy Ltd, 2 Bergman Street, Rehovot, Israel
| | - Yoav Barak
- Bio-Nano Unit, Chemical Research Support, The Weizmann Institute of Science, 761000 Rehovot, Israel
| | - Melina Shamshoum
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Ilya Borovok
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, Israel
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, Israel
| | - Bareket Dassa
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Yitzhak Hadar
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food and Environment, The Advanced School for Environmental Studies, The Hebrew University of Jerusalem, 76100 Rehovot, Israel
| | - Ely Morag
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Edward A. Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 76100 Rehovot, Israel
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de Eugenio LI, Méndez-Líter JA, Nieto-Domínguez M, Alonso L, Gil-Muñoz J, Barriuso J, Prieto A, Martínez MJ. Differential β-glucosidase expression as a function of carbon source availability in Talaromyces amestolkiae: a genomic and proteomic approach. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:161. [PMID: 28649280 PMCID: PMC5481877 DOI: 10.1186/s13068-017-0844-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 06/08/2017] [Indexed: 05/07/2023]
Abstract
BACKGROUND Genomic and proteomic analysis are potent tools for metabolic characterization of microorganisms. Although cellulose usually triggers cellulase production in cellulolytic fungi, the secretion of the different enzymes involved in polymer conversion is subjected to different factors, depending on growth conditions. These enzymes are key factors in biomass exploitation for second generation bioethanol production. Although highly effective commercial cocktails are available, they are usually deficient for β-glucosidase activity, and genera like Penicillium and Talaromyces are being explored for its production. RESULTS This article presents the description of Talaromyces amestolkiae as a cellulase-producer fungus that secretes high levels of β-glucosidase. β-1,4-endoglucanase, exoglucanase, and β-glucosidase activities were quantified in the presence of different carbon sources. Although the two first activities were only induced with cellulosic substrates, β-glucosidase levels were similar in all carbon sources tested. Sequencing and analysis of the genome of this fungus revealed multiple genes encoding β-glucosidases. Extracellular proteome analysis showed different induction patterns. In all conditions assayed, glycosyl hydrolases were the most abundant proteins in the supernatants, albeit the ratio of the diverse enzymes from this family depended on the carbon source. At least two different β-glucosidases have been identified in this work: one is induced by cellulose and the other one is carbon source-independent. The crudes induced by Avicel and glucose were independently used as supplements for saccharification of slurry from acid-catalyzed steam-exploded wheat straw, obtaining the highest yields of fermentable glucose using crudes induced by cellulose. CONCLUSIONS The genome of T. amestolkiae contains several genes encoding β-glucosidases and the fungus secretes high levels of this activity, regardless of the carbon source availability, although its production is repressed by glucose. Two main different β-glucosidases have been identified from proteomic shotgun analysis. One of them is produced under different carbon sources, while the other is induced in cellulosic substrates and is a good supplement to Celluclast in saccharification of pretreated wheat straw.
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Affiliation(s)
- Laura I. de Eugenio
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Juan A. Méndez-Líter
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Manuel Nieto-Domínguez
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Lola Alonso
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
- Genetic and Molecular Epidemiology Group, Human Cancer Genetics Programme, Spanish National Cancer Research Centre, CNIO, Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Jesús Gil-Muñoz
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Jorge Barriuso
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Alicia Prieto
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - María Jesús Martínez
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
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Lü F, Chai L, Shao L, He P. Precise pretreatment of lignocellulose: relating substrate modification with subsequent hydrolysis and fermentation to products and by-products. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:88. [PMID: 28400859 PMCID: PMC5387280 DOI: 10.1186/s13068-017-0775-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 04/05/2017] [Indexed: 05/25/2023]
Abstract
BACKGROUND Pretreatment is a crucial step for valorization of lignocellulosic biomass into valuable products such as H2, ethanol, acids, and methane. As pretreatment can change several decisive factors concurrently, it is difficult to predict its effectiveness. Furthermore, the effectiveness of pretreatments is usually assessed by enzymatic digestibility or merely according to the yield of the target fermentation products. The present study proposed the concept of "precise pretreatment," distinguished the major decisive factors of lignocellulosic materials by precise pretreatment, and evaluated the complete profile of all fermentation products and by-products. In brief, hemicellulose and lignin were selectively removed from dewaxed rice straw, and the cellulose was further modified to alter the crystalline allomorphs. The subsequent fermentation performance of the selectively pretreated lignocellulose was assessed using the cellulolytic, ethanologenic, and hydrogenetic Clostridium thermocellum through a holistic characterization of the liquid, solid, and gaseous products and residues. RESULTS The transformation of crystalline cellulose forms from I to II and from Iα to Iβ improved the production of H2 and ethanol by 65 and 29%, respectively. At the same time, the hydrolysis efficiency was merely improved by 10%, revealing that the crystalline forms not only influenced the accessibility of cellulose but also affected the metabolic preferences and flux of the system. The fermentation efficiency was independent of the specific surface area and degree of polymerization. Furthermore, the pretreatments resulted in 43-45% of the carbon in the liquid hydrolysates unexplainable by forming ethanol and acetate products. A tandem pretreatment with peracetic acid and alkali improved ethanol production by 45.5%, but also increased the production of non-ethanolic low-value by-products by 136%, resulting in a huge burden on wastewater treatment requirements. CONCLUSION Cellulose allomorphs significantly affected fermentation metabolic pathway, except for hydrolysis efficiency. Furthermore, with the increasing effectiveness of the pretreatment for ethanol production, more non-ethanolic low-value by-products or contaminants were produced, intensifying environmental burden. Therefore, the effectiveness of the pretreatment should not only be determined on the basis of energy auditing and inhibitors generated, but should also be assessed in terms of the environmental benefits of the whole integrated system from a holistic view.
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Affiliation(s)
- Fan Lü
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 China
| | - Lina Chai
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 China
| | - Liming Shao
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092 China
| | - Pinjing He
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092 China
- Centre for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban–Rural Development (MOHURD) of China, Shanghai, 200092 China
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16
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Thompson RA, Dahal S, Garcia S, Nookaew I, Trinh CT. Exploring complex cellular phenotypes and model-guided strain design with a novel genome-scale metabolic model of Clostridium thermocellum DSM 1313 implementing an adjustable cellulosome. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:194. [PMID: 27602057 PMCID: PMC5012057 DOI: 10.1186/s13068-016-0607-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/26/2016] [Indexed: 05/06/2023]
Abstract
BACKGROUND Clostridium thermocellum is a gram-positive thermophile that can directly convert lignocellulosic material into biofuels. The metabolism of C. thermocellum contains many branches and redundancies which limit biofuel production, and typical genetic techniques are time-consuming. Further, the genome sequence of a genetically tractable strain C. thermocellum DSM 1313 has been recently sequenced and annotated. Therefore, developing a comprehensive, predictive, genome-scale metabolic model of DSM 1313 is desired for elucidating its complex phenotypes and facilitating model-guided metabolic engineering. RESULTS We constructed a genome-scale metabolic model iAT601 for DSM 1313 using the KEGG database as a scaffold and an extensive literature review and bioinformatic analysis for model refinement. Next, we used several sets of experimental data to train the model, e.g., estimation of the ATP requirement for growth-associated maintenance (13.5 mmol ATP/g DCW/h) and cellulosome synthesis (57 mmol ATP/g cellulosome/h). Using our tuned model, we investigated the effect of cellodextrin lengths on cell yields, and could predict in silico experimentally observed differences in cell yield based on which cellodextrin species is assimilated. We further employed our tuned model to analyze the experimentally observed differences in fermentation profiles (i.e., the ethanol to acetate ratio) between cellobiose- and cellulose-grown cultures and infer regulatory mechanisms to explain the phenotypic differences. Finally, we used the model to design over 250 genetic modification strategies with the potential to optimize ethanol production, 6155 for hydrogen production, and 28 for isobutanol production. CONCLUSIONS Our developed genome-scale model iAT601 is capable of accurately predicting complex cellular phenotypes under a variety of conditions and serves as a high-quality platform for model-guided strain design and metabolic engineering to produce industrial biofuels and chemicals of interest.
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Affiliation(s)
- R. Adam Thompson
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN 37996 USA
- Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Sanjeev Dahal
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Comparative Genomics Group, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Sergio Garcia
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Dr., DO#432, Knoxville, TN 37996 USA
| | - Intawat Nookaew
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Comparative Genomics Group, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Biomedical Informatics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205 USA
| | - Cong T. Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN 37996 USA
- Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Dr., DO#432, Knoxville, TN 37996 USA
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17
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Wang M, Zhao Q, Li L, Niu K, Li Y, Wang F, Jiang B, Liu K, Jiang Y, Fang X. Contributing factors in the improvement of cellulosic H2 production in Clostridium thermocellum/Thermoanaerobacterium co-cultures. Appl Microbiol Biotechnol 2016; 100:8607-20. [PMID: 27538932 DOI: 10.1007/s00253-016-7776-1] [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: 06/02/2016] [Revised: 07/17/2016] [Accepted: 08/01/2016] [Indexed: 02/04/2023]
Abstract
Lignocellulosic biohydrogen is a promising renewable energy source that could be a potential alternative to the unsustainable fossil fuel-based energy. Biohydrogen production could be performed by Clostridium thermocellum that is the fastest known cellulose-degrading bacterium. Previous investigations have shown that the co-culture of C. thermocellum JN4 and a non-cellulolytic bacterium Thermoanaerobacterium thermosaccharolyticum GD17 produces more hydrogen than the C. thermocellum JN4 mono-culture, but the mechanism of this improvement is unknown. In this work, we carried out genomic and evolutionary analysis of hydrogenase-coding genes in C. thermocellum and T. thermosaccharolyticum, identifying one Ech-type [NiFe] hydrogenase complex in each species, and, respectively, five and four monomeric or multimeric [FeFe] hydrogenases in the two species. Further transcriptional analysis showed hydrogenase-coding genes in C. thermocellum are regulated by carbon sources, while hydrogenase-coding genes in T. thermosaccharolyticum are not. However, comparison between transcriptional abundance of hydrogenase-coding genes in mono- and co-cultures showed the co-culturing condition leads to transcriptional changes of hydrogenase-coding genes in T. thermosaccharolyticum but not C. thermocellum. Further metabolic analysis showed T. thermosaccharolyticum produces H2 at a rate 4-12-fold higher than C. thermocellum. These findings lead to the suggestion that the improvement of H2 production in the co-culture over mono-culture should be attributed to changes in T. thermosaccharolyticum but not C. thermocellum. Further suggestions can be made that C. thermocellum and T. thermosaccharolyticum perform highly specialized tasks in the co-culture, and optimization of the co-culture for more lignocellulosic biohydrogen production should be focused on the improvement of the non-cellulolytic bacterium.
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Affiliation(s)
- Mingyu Wang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Qi Zhao
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Ling Li
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Kangle Niu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Yi Li
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China.,Taishan College, Shandong University, Jinan, 250100, China
| | - Fangzhong Wang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Baojie Jiang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Kuimei Liu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Yi Jiang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Xu Fang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, 250100, China.
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18
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Munir RI, Spicer V, Krokhin OV, Shamshurin D, Zhang X, Taillefer M, Blunt W, Cicek N, Sparling R, Levin DB. Transcriptomic and proteomic analyses of core metabolism in Clostridium termitidis CT1112 during growth on α-cellulose, xylan, cellobiose and xylose. BMC Microbiol 2016; 16:91. [PMID: 27215540 PMCID: PMC4877739 DOI: 10.1186/s12866-016-0711-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 05/16/2016] [Indexed: 01/15/2023] Open
Abstract
Background Clostridium termitidis CT1112 is an anaerobic, Gram-positive, mesophilic, spore-forming, cellulolytic bacterium, originally isolated from the gut of a wood feeding termite Nasusitermes lujae. It has the ability to hydrolyze both cellulose and hemicellulose, and ferment the degradation products to acetate, formate, ethanol, lactate, H2, and CO2. It is therefore ges in gene and gene product expression during growth of C. termitidis on cellobiose, xylose, xylan, and α–cellulose. Results Correlation of transcriptome and proteome data with growth and fermentation profiles identified putative carbon-catabolism pathways in C. termitidis. The majority of the proteins associated with central metabolism were detected in high abundance. While major differences were not observed in gene and gene-product expression for enzymes associated with metabolic pathways under the different substrate conditions, xylulokinase and xylose isomerase of the pentose phosphate pathway were found to be highly up-regulated on five carbon sugars compared to hexoses. In addition, genes and gene-products associated with a variety of cellulosome and non-cellulosome associated CAZymes were found to be differentially expressed. Specifically, genes for cellulosomal enzymes and components were highly expressed on α–cellulose, while xylanases and glucosidases were up-regulated on 5 carbon sugars with respect to cellobiose. Chitinase and cellobiophosphorylases were the predominant CAZymes expressed on cellobiose. In addition to growth on xylan, the simultaneous consumption of two important lignocellulose constituents, cellobiose and xylose was also demonstrated. Conclusion There are little changes in core-metabolic pathways under the different carbon sources compared. The most significant differences were found to be associated with the CAZymes, as well as specific up regulation of some key components of the pentose phosphate pathway in the presence of xylose and xylan. This study has enhanced our understanding of the physiology and metabolism of C. termitidis, and provides a foundation for future studies on metabolic engineering to optimize biofuel production from natural biomass. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0711-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Riffat I Munir
- Department of Biosystems Engineering, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada
| | - Victor Spicer
- Department of Physics and Astronomy, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada.,Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada
| | - Oleg V Krokhin
- Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada
| | - Dmitry Shamshurin
- Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada
| | - XiangLi Zhang
- Department of Plant Science, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada
| | - Marcel Taillefer
- Department of Microbiology, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada
| | - Warren Blunt
- Department of Biosystems Engineering, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada
| | - Nazim Cicek
- Department of Biosystems Engineering, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada
| | - David B Levin
- Department of Biosystems Engineering, University of Manitoba, R3T 5N6, Winnipeg, MB, Canada.
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Lal S, Levin DB. Comparative Genomics of Core Metabolism Genes of Cellulolytic and Non-cellulolytic Clostridium Species. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016; 156:79-112. [PMID: 26907553 DOI: 10.1007/10_2015_5007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Microbial production of fuels such as ethanol, butanol, hydrogen (H2), and methane (CH4) from waste biomass has the potential to provide sustainable energy systems that can displace fossil fuel consumption. Screening for microbial diversity and genome sequencing of a wide-range of microorganisms can identify organisms with natural abilities to synthesize these alternative fuels and/or other biotechnological applications. Clostridium species are the most widely studied strict anaerobes capable of fermentative synthesis of ethanol, butanol, or hydrogen directly from waste biomass. Clostridium termitidis CT1112 is a mesophilic, cellulolytic species capable of direct cellulose fermentation to ethanol and organic acids, with concomitant synthesis of H2 and CO2. On the basis of 16S ribosomal RNA (rRNA) and chaperonin 60 (cpn60) gene sequence data, phylogenetic analyses revealed a close relationship between C. termitidis and C. cellobioparum. Comparative bioinformatic analyses of the C. termitidis genome with 18 cellulolytic and 10 non-cellulolytic Clostridium species confirmed this relationship, and further revealed that the majority of core metabolic pathway genes in C. termitidis and C. cellobioparum share more than 90% amino acid sequence identity. The gene loci and corresponding amino acid sequences of the encoded enzymes for each pathway were correlated by percentage identity, higher score (better alignment), and lowest e-value (most significant "hit"). In addition, the function of each enzyme was proposed by conserved domain analysis. In this chapter we discuss the comparative analysis of metabolic pathways involved in synthesis of various useful products by cellulolytic and non-cellulolytic biofuel and solvent producing Clostridium species. This study has generated valuable information concerning the core metabolism genes and pathways of C. termitidis CT1112, which is helpful in developing metabolic engineering strategies to enhance its natural capacity for better industrial applications.
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Affiliation(s)
- Sadhana Lal
- Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, Canada, R3T 5V6
| | - David B Levin
- Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, Canada, R3T 5V6.
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Ma J, Zhang K, Liao H, Hector SB, Shi X, Li J, Liu B, Xu T, Tong C, Liu X, Zhu Y. Genomic and secretomic insight into lignocellulolytic system of an endophytic bacterium Pantoea ananatis Sd-1. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:25. [PMID: 26839588 PMCID: PMC4736469 DOI: 10.1186/s13068-016-0439-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Accepted: 01/14/2016] [Indexed: 05/06/2023]
Abstract
BACKGROUND Exploring microorganisms especially bacteria associated with the degradation of lignocellulosic biomass shows great potentials in biofuels production. The rice endophytic bacterium Pantoea ananatis Sd-1 with strong lignocellulose degradation capacity has been reported in our previous study. However, a comprehensive analysis of its corresponding degradative system has not yet been conducted. The aim of this work is to identify and characterize the lignocellulolytic enzymes of the bacterium to understand its mechanism of lignocellulose degradation and facilitate its application in sustainable energy production. RESULTS The genomic analysis revealed that there are 154 genes encoding putative carbohydrate-active enzymes (CAZy) in P. ananatis Sd-1. This number is higher than that of compared cellulolytic and ligninolytic bacteria as well as other eight P. ananatis strains. The CAZy in P. ananatis Sd-1 contains a complete repertoire of enzymes required for cellulose and hemicellulose degradation. In addition, P. ananatis Sd-1 also possesses plenty of genes encoding potential ligninolytic relevant enzymes, such as multicopper oxidase, catalase/hydroperoxidase, glutathione S-transferase, and quinone oxidoreductase. Quantitative real-time PCR analysis of parts of genes encoding lignocellulolytic enzymes revealed that they were significantly up-regulated (at least P < 0.05) in presence of rice straw. Further identification of secretome of P. ananatis Sd-1 by nano liquid chromatography-tandem mass spectrometry confirmed that considerable amounts of proteins involved in lignocellulose degradation were only detected in rice straw cultures. Rice straw saccharification levels by the secretome of P. ananatis Sd-1 reached 129.11 ± 2.7 mg/gds. Correspondingly, the assay of several lignocellulolytic enzymes including endoglucanase, exoglucanase, β-glucosidase, xylanase-like, lignin peroxidase-like, and laccase-like activities showed that these enzymes were more active in rice straw relative to glucose substrates. The high enzymes activities were not attributed to bacterial cell densities but to the difference of secreted protein contents. CONCLUSION Our results indicate that P. ananatis Sd-1 can produce considerable lignocellulolytic enzymes including cellulases, hemicellulases, and ligninolytic relevant enzymes. The high activities of those enzymes could be efficiently induced by lignocellulosic biomass. This identified degradative system is valuable for the lignocellulosic bioenergy industry.
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Affiliation(s)
- Jiangshan Ma
- />Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
| | - Keke Zhang
- />Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
| | - Hongdong Liao
- />Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
| | - Stanton B. Hector
- />Department of Genetics, Institute for Plant Biotechnology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602 South Africa
- />DNA Sequencing Unit, Central Analytical Facility, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602 South Africa
| | - Xiaowei Shi
- />Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
| | - Jianglin Li
- />State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
| | - Bin Liu
- />Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
| | - Ting Xu
- />Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
| | - Chunyi Tong
- />Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
| | - Xuanming Liu
- />Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
| | - Yonghua Zhu
- />Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha, 410008 Hunan People’s Republic of China
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Ma YJ, Sun XH, Xu XY, Zhao Y, Pan YJ, Hwang CA, Wu VCH. Investigation of Reference Genes in Vibrio parahaemolyticus for Gene Expression Analysis Using Quantitative RT-PCR. PLoS One 2015; 10:e0144362. [PMID: 26659406 PMCID: PMC4676679 DOI: 10.1371/journal.pone.0144362] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 11/17/2015] [Indexed: 01/14/2023] Open
Abstract
Vibrio parahaemolyticus is a significant human pathogen capable of causing foodborne gastroenteritis associated with the consumption of contaminated raw or undercooked seafood. Quantitative RT-PCR (qRT-PCR) is a useful tool for studying gene expression in V. parahaemolyticus to characterize its virulence factors and understand the effect of environmental conditions on its pathogenicity. However, there is not a stable gene in V. parahaemolyticus that has been identified for use as a reference gene for qRT-PCR. This study evaluated the stability of 6 reference genes (16S rRNA, recA, rpoS, pvsA, pvuA, and gapdh) in 5 V. parahaemolyticus strains (O3:K6-clinical strain-tdh+, ATCC33846-tdh+, ATCC33847-tdh+, ATCC17802-trh+, and F13-environmental strain-tdh+) cultured at 4 different temperatures (15, 25, 37 and 42°C). Stability values were calculated using GeNorm, NormFinder, BestKeeper, and Delta CT algorithms. The results indicated that recA was the most stably expressed gene in the V. parahaemolyticus strains cultured at different temperatures. This study examined multiple V. parahaemolyticus strains and growth temperatures, hence the finding provided stronger evidence that recA can be used as a reference gene for gene expression studies in V. parahaemolyticus.
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Affiliation(s)
- Yue-jiao Ma
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, People's Republic of China
- Shanghai Engineering Research Center of Aquatic Product Processing & Preservation, Shanghai 201306, China
| | - Xiao-hong Sun
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, People's Republic of China
- Shanghai Engineering Research Center of Aquatic Product Processing & Preservation, Shanghai 201306, China
- * E-mail: (VCHW); (XS)
| | - Xiao-yan Xu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai, People's Republic of China
| | - Yong Zhao
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, People's Republic of China
- Shanghai Engineering Research Center of Aquatic Product Processing & Preservation, Shanghai 201306, China
| | - Ying-jie Pan
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, People's Republic of China
- Shanghai Engineering Research Center of Aquatic Product Processing & Preservation, Shanghai 201306, China
| | - Cheng-An Hwang
- Residue Chemistry and Predictive Microbiology Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Wyndmoor, PA, 19038, United States of America
| | - Vivian C. H. Wu
- The Pathogenic Microbiology Laboratory, School of Food and Agriculture, University of Maine, Orono, ME, 04469–5735, United States of America
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA, 94710, United States of America
- * E-mail: (VCHW); (XS)
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Lin PP, Mi L, Morioka AH, Yoshino KM, Konishi S, Xu SC, Papanek BA, Riley LA, Guss AM, Liao JC. Consolidated bioprocessing of cellulose to isobutanol using Clostridium thermocellum. Metab Eng 2015; 31:44-52. [DOI: 10.1016/j.ymben.2015.07.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/06/2015] [Accepted: 07/01/2015] [Indexed: 10/23/2022]
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Sand A, Holwerda EK, Ruppertsberger NM, Maloney M, Olson DG, Nataf Y, Borovok I, Sonenshein AL, Bayer EA, Lamed R, Lynd LR, Shoham Y. Three cellulosomal xylanase genes inClostridium thermocellumare regulated by both vegetative SigA (σA) and alternative SigI6 (σI6) factors. FEBS Lett 2015; 589:3133-40. [DOI: 10.1016/j.febslet.2015.08.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 08/10/2015] [Accepted: 08/14/2015] [Indexed: 11/29/2022]
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Li Z, Chen Y, Liu D, Zhao N, Cheng H, Ren H, Guo T, Niu H, Zhuang W, Wu J, Ying H. Involvement of glycolysis/gluconeogenesis and signaling regulatory pathways in Saccharomyces cerevisiae biofilms during fermentation. Front Microbiol 2015; 6:139. [PMID: 25755652 PMCID: PMC4337339 DOI: 10.3389/fmicb.2015.00139] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 02/05/2015] [Indexed: 11/16/2022] Open
Abstract
Compared to free (free-living) cells, biofilm cells show increased resistance and stability to high-pressure fermentation conditions, although the reasons underlying these phenomena remain unclear. Here, we investigated biofilm formation with immobilized Saccharomyces cerevisiae cells grown on fiber surfaces during the process of ethanol fermentation. The development of biofilm colonies was visualized by fluorescent labeling and confocal microscopy. RNA from yeast cells at three different biofilm development periods was extracted and sequenced by high-throughput sequencing. We quantitated gene expression differences between biofilm cells and free cells and found that 2098, 1556, and 927 genes were significantly differentially expressed, respectively. We also validated the expression of previously reported genes and identified novel genes and pathways under the control of this system. Statistical analysis revealed that biofilm genes show significant gene expression changes principally in the initial period of biofilm formation compared to later periods. Carbohydrate metabolism, amino acid metabolism, signal transduction, and oxidoreductase activity were needed for biofilm formation. In contrast to previous findings, we observed some differential expression performances of FLO family genes, indicating that cell aggregation in our immobilized fermentation system was possibly independent of flocculation. Cyclic AMP-protein kinase A and mitogen-activated protein kinase pathways regulated signal transduction pathways during yeast biofilm formation. We found that carbohydrate metabolism, especially glycolysis/gluconeogenesis, played a key role in the development of S. cerevisiae biofilms. This work provides an important dataset for future studies aimed at gaining insight into the regulatory mechanisms of immobilized cells in biofilms, as well as for optimizing bioprocessing applications with S. cerevisiae.
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Affiliation(s)
- Zhenjian Li
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China ; State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Yong Chen
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Dong Liu
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Nan Zhao
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Hao Cheng
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Hengfei Ren
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Ting Guo
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Huanqing Niu
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Wei Zhuang
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Jinglan Wu
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
| | - Hanjie Ying
- National Engineering Research Center for Biotechnology, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China ; State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University Nanjing, China
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25
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Lee S, J. Mitchell R. Perspectives on the use of transcriptomics to advance biofuels. AIMS BIOENGINEERING 2015. [DOI: 10.3934/bioeng.2015.4.487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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26
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Christopherson MR, Dawson JA, Stevenson DM, Cunningham AC, Bramhacharya S, Weimer PJ, Kendziorski C, Suen G. Unique aspects of fiber degradation by the ruminal ethanologen Ruminococcus albus 7 revealed by physiological and transcriptomic analysis. BMC Genomics 2014; 15:1066. [PMID: 25477200 PMCID: PMC4300822 DOI: 10.1186/1471-2164-15-1066] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 11/24/2014] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Bacteria in the genus Ruminococcus are ubiquitous members of the mammalian gastrointestinal tract. In particular, they are important in ruminants where they digest a wide range of plant cell wall polysaccharides. For example, Ruminococcus albus 7 is a primary cellulose degrader that produces acetate usable by its bovine host. Moreover, it is one of the few organisms that ferments cellulose to form ethanol at mesophilic temperatures in vitro. The mechanism of cellulose degradation by R. albus 7 is not well-defined and is thought to involve pilin-like proteins, unique carbohydrate-binding domains, a glycocalyx, and cellulosomes. Here, we used a combination of comparative genomics, fermentation analyses, and transcriptomics to further clarify the cellulolytic and fermentative potential of R. albus 7. RESULTS A comparison of the R. albus 7 genome sequence against the genome sequences of related bacteria that either encode or do not encode cellulosomes revealed that R. albus 7 does not encode for most canonical cellulosomal components. Fermentation analysis of R. albus 7 revealed the ability to produce ethanol and acetate on a wide range of fibrous substrates in vitro. Global transcriptomic analysis of R. albus 7 grown at identical dilution rates on cellulose and cellobiose in a chemostat showed that this bacterium, when growing on cellulose, utilizes a carbohydrate-degrading strategy that involves increased transcription of the rare carbohydrate-binding module (CBM) family 37 domain and the tryptophan biosynthetic operon. CONCLUSIONS Our data suggest that R. albus 7 does not use canonical cellulosomal components to degrade cellulose, but rather up-regulates the expression of CBM37-containing enzymes and tryptophan biosynthesis. This study contributes to a revised model of carbohydrate degradation by this key member of the rumen ecosystem.
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Affiliation(s)
| | | | | | | | | | | | | | - Garret Suen
- Department of Bacteriology, University of Wisconsin-Madison, 5159 Microbial Sciences Building, 1550 Linden Drive, Madison, WI 53706-1521, USA.
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Akinosho H, Yee K, Close D, Ragauskas A. The emergence of Clostridium thermocellum as a high utility candidate for consolidated bioprocessing applications. Front Chem 2014; 2:66. [PMID: 25207268 PMCID: PMC4143619 DOI: 10.3389/fchem.2014.00066] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 07/28/2014] [Indexed: 01/25/2023] Open
Abstract
First isolated in 1926, Clostridium thermocellum has recently received increased attention as a high utility candidate for use in consolidated bioprocessing (CBP) applications. These applications, which seek to process lignocellulosic biomass directly into useful products such as ethanol, are gaining traction as economically feasible routes toward the production of fuel and other high value chemical compounds as the shortcomings of fossil fuels become evident. This review evaluates C. thermocellum's role in this transitory process by highlighting recent discoveries relating to its genomic, transcriptomic, proteomic, and metabolomic responses to varying biomass sources, with a special emphasis placed on providing an overview of its unique, multivariate enzyme cellulosome complex and the role that this structure performs during biomass degradation. Both naturally evolved and genetically engineered strains are examined in light of their unique attributes and responses to various biomass treatment conditions, and the genetic tools that have been employed for their creation are presented. Several future routes for potential industrial usage are presented, and it is concluded that, although there have been many advances to significantly improve C. thermocellum's amenability to industrial use, several hurdles still remain to be overcome as this unique organism enjoys increased attention within the scientific community.
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Affiliation(s)
- Hannah Akinosho
- School of Chemistry and Biochemistry, Institute of Paper Science and Technology, Georgia Institute of Technology Atlanta, GA, USA ; Oak Ridge National Laboratory, BioEnergy Science Center Oak Ridge, TN, USA
| | - Kelsey Yee
- Oak Ridge National Laboratory, BioEnergy Science Center Oak Ridge, TN, USA ; Biosciences Division, Oak Ridge National Laboratory Oak Ridge, TN, USA
| | - Dan Close
- Biosciences Division, Oak Ridge National Laboratory Oak Ridge, TN, USA
| | - Arthur Ragauskas
- Oak Ridge National Laboratory, BioEnergy Science Center Oak Ridge, TN, USA ; Department of Chemical and Biomolecular Engineering and Department of Forestry, Wildlife, and Fisheries, University of Tennessee Knoxville, TN, USA
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Rydzak T, Grigoryan M, Cunningham ZJ, Krokhin OV, Ezzati P, Cicek N, Levin DB, Wilkins JA, Sparling R. Insights into electron flux through manipulation of fermentation conditions and assessment of protein expression profiles in Clostridium thermocellum. Appl Microbiol Biotechnol 2014; 98:6497-510. [PMID: 24841118 DOI: 10.1007/s00253-014-5798-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/15/2014] [Accepted: 04/27/2014] [Indexed: 02/06/2023]
Abstract
While annotation of the genome sequence of Clostridium thermocellum has allowed predictions of pathways catabolizing cellobiose to end products, ambiguities have persisted with respect to the role of various proteins involved in electron transfer reactions. A combination of growth studies modulating carbon and electron flow and multiple reaction monitoring (MRM) mass spectrometry measurements of proteins involved in central metabolism and electron transfer was used to determine the key enzymes involved in channeling electrons toward fermentation end products. Specifically, peptides belonging to subunits of ferredoxin-dependent hydrogenase and NADH:ferredoxin oxidoreductase (NFOR) were low or below MRM detection limits when compared to most central metabolic proteins measured. The significant increase in H2 versus ethanol synthesis in response to either co-metabolism of pyruvate and cellobiose or hypophosphite mediated pyruvate:formate lyase inhibition, in conjunction with low levels of ferredoxin-dependent hydrogenase and NFOR, suggest that highly expressed putative bifurcating hydrogenases play a substantial role in reoxidizing both reduced ferredoxin and NADH simultaneously. However, product balances also suggest that some of the additional reduced ferredoxin generated through increased flux through pyruvate:ferredoxin oxidoreductase must be ultimately converted into NAD(P)H either directly via NADH-dependent reduced ferredoxin:NADP(+) oxidoreductase (NfnAB) or indirectly via NADPH-dependent hydrogenase. While inhibition of hydrogenases with carbon monoxide decreased H2 production 6-fold and redirected flux from pyruvate:ferredoxin oxidoreductase to pyruvate:formate lyase, the decrease in CO2 was only 20 % of that of the decrease in H2, further suggesting that an alternative redox system coupling ferredoxin and NAD(P)H is active in C. thermocellum in lieu of poorly expressed ferredoxin-dependent hydrogenase and NFOR.
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Affiliation(s)
- Thomas Rydzak
- Department of Microbiology, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
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Wei H, Fu Y, Magnusson L, Baker JO, Maness PC, Xu Q, Yang S, Bowersox A, Bogorad I, Wang W, Tucker MP, Himmel ME, Ding SY. Comparison of transcriptional profiles of Clostridium thermocellum grown on cellobiose and pretreated yellow poplar using RNA-Seq. Front Microbiol 2014; 5:142. [PMID: 24782837 PMCID: PMC3990059 DOI: 10.3389/fmicb.2014.00142] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 03/19/2014] [Indexed: 01/01/2023] Open
Abstract
The anaerobic, thermophilic bacterium, Clostridium thermocellum, secretes multi-protein enzyme complexes, termed cellulosomes, which synergistically interact with the microbial cell surface and efficiently disassemble plant cell wall biomass. C. thermocellum has also been considered a potential consolidated bioprocessing (CBP) organism due to its ability to produce the biofuel products, hydrogen, and ethanol. We found that C. thermocellum fermentation of pretreated yellow poplar (PYP) produced 30 and 39% of ethanol and hydrogen product concentrations, respectively, compared to fermentation of cellobiose. RNA-seq was used to analyze the transcriptional profiles of these cells. The PYP-grown cells taken for analysis at the late stationary phase showed 1211 genes up-regulated and 314 down-regulated by more than two-fold compared to the cellobiose-grown cells. These affected genes cover a broad spectrum of specific functional categories. The transcriptional analysis was further validated by sub-proteomics data taken from the literature; as well as by quantitative reverse transcription-PCR (qRT-PCR) analyses of selected genes. Specifically, 47 cellulosomal protein-encoding genes, genes for 4 pairs of SigI-RsgI for polysaccharide sensing, 7 cellodextrin ABC transporter genes, and a set of NAD(P)H hydogenase and alcohol dehydrogenase genes were up-regulated for cells growing on PYP compared to cellobiose. These genes could be potential candidates for future studies aimed at gaining insight into the regulatory mechanism of this organism as well as for improvement of C. thermocellum in its role as a CBP organism.
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Affiliation(s)
- Hui Wei
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Yan Fu
- Center for Plant Genomics, Iowa State University Ames, IA, USA
| | - Lauren Magnusson
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - John O Baker
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Pin-Ching Maness
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Qi Xu
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Shihui Yang
- National Bioenergy Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Andrew Bowersox
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA ; National Bioenergy Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Igor Bogorad
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Wei Wang
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Melvin P Tucker
- National Bioenergy Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Michael E Himmel
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Shi-You Ding
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
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Dourado MN, Bogas AC, Pomini AM, Andreote FD, Quecine MC, Marsaioli AJ, Araújo WL. Methylobacterium-plant interaction genes regulated by plant exudate and quorum sensing molecules. Braz J Microbiol 2014; 44:1331-9. [PMID: 24688531 PMCID: PMC3958207 DOI: 10.1590/s1517-83822013000400044] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 04/04/2013] [Indexed: 11/21/2022] Open
Abstract
Bacteria from the genus Methylobacterium interact symbiotically (endophytically and epiphytically) with different plant species. These interactions can promote plant growth or induce systemic resistance, increasing plant fitness. The plant colonization is guided by molecular communication between bacteria-bacteria and bacteria-plants, where the bacteria recognize specific exuded compounds by other bacteria (e.g. homoserine molecules) and/or by the plant roots (e.g. flavonoids, ethanol and methanol), respectively. In this context, the aim of this study was to evaluate the effect of quorum sensing molecules (N-acyl-homoserine lactones) and plant exudates (including ethanol) in the expression of a series of bacterial genes involved in Methylobacterium-plant interaction. The selected genes are related to bacterial metabolism (mxaF), adaptation to stressful environment (crtI, phoU and sss), to interactions with plant metabolism compounds (acdS) and pathogenicity (patatin and phoU). Under in vitro conditions, our results showed the differential expression of some important genes related to metabolism, stress and pathogenesis, thereby AHL molecules up-regulate all tested genes, except phoU, while plant exudates induce only mxaF gene expression. In the presence of plant exudates there is a lower bacterial density (due the endophytic and epiphytic colonization), which produce less AHL, leading to down regulation of genes when compared to the control. Therefore, bacterial density, more than plant exudate, influences the expression of genes related to plant-bacteria interaction.
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Affiliation(s)
| | | | - Armando M Pomini
- Departamento de Química, Universidade Estadual de Maringá, Maringá, PR, Brazil
| | - Fernando Dini Andreote
- Departamento de Ciências do Solos, Escola Superior de Agricultura "Luiz de Queiróz", Universidade de São Paulo, Piracicaba, SP, Brazil
| | | | - Anita J Marsaioli
- Instituto de Química, Universidade de Campinas, Campinas, São Paulo, Brazil
| | - Welington Luiz Araújo
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil
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Li Y, Xu T, Tschaplinski TJ, Engle NL, Yang Y, Graham DE, He Z, Zhou J. Improvement of cellulose catabolism in Clostridium cellulolyticum by sporulation abolishment and carbon alleviation. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:25. [PMID: 24555718 PMCID: PMC3936895 DOI: 10.1186/1754-6834-7-25] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Accepted: 02/06/2014] [Indexed: 05/23/2023]
Abstract
BACKGROUND Clostridium cellulolyticum can degrade lignocellulosic biomass, and ferment the soluble sugars to produce valuable chemicals such as lactate, acetate, ethanol and hydrogen. However, the cellulose utilization efficiency of C. cellulolyticum still remains very low, impeding its application in consolidated bioprocessing for biofuels production. In this study, two metabolic engineering strategies were exploited to improve cellulose utilization efficiency, including sporulation abolishment and carbon overload alleviation. RESULTS The spo0A gene at locus Ccel_1894, which encodes a master sporulation regulator was inactivated. The spo0A mutant abolished the sporulation ability. In a high concentration of cellulose (50 g/l), the performance of the spo0A mutant increased dramatically in terms of maximum growth, final concentrations of three major metabolic products, and cellulose catabolism. The microarray and gas chromatography-mass spectrometry (GC-MS) analyses showed that the valine, leucine and isoleucine biosynthesis pathways were up-regulated in the spo0A mutant. Based on this information, a partial isobutanol producing pathway modified from valine biosynthesis was introduced into C. cellulolyticum strains to further increase cellulose consumption by alleviating excessive carbon load. The introduction of this synthetic pathway to the wild-type strain improved cellulose consumption from 17.6 g/l to 28.7 g/l with a production of 0.42 g/l isobutanol in the 50 g/l cellulose medium. However, the spo0A mutant strain did not appreciably benefit from introduction of this synthetic pathway and the cellulose utilization efficiency did not further increase. A technical highlight in this study was that an in vivo promoter strength evaluation protocol was developed using anaerobic fluorescent protein and flow cytometry for C. cellulolyticum. CONCLUSIONS In this study, we inactivated the spo0A gene and introduced a heterologous synthetic pathway to manipulate the stress response to heavy carbon load and accumulation of metabolic products. These findings provide new perspectives to enhance the ability of cellulolytic bacteria to produce biofuels and biocommodities with high efficiency and at low cost directly from lignocellulosic biomass.
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Affiliation(s)
- Yongchao Li
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, 101 David L. Boren Boulevard, Norman, OK 73019, USA
| | - Tao Xu
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, 101 David L. Boren Boulevard, Norman, OK 73019, USA
| | - Timothy J Tschaplinski
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Nancy L Engle
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Yunfeng Yang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - David E Graham
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Zhili He
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, 101 David L. Boren Boulevard, Norman, OK 73019, USA
| | - Jizhong Zhou
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, 101 David L. Boren Boulevard, Norman, OK 73019, USA
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
- Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Yaniv O, Fichman G, Borovok I, Shoham Y, Bayer EA, Lamed R, Shimon LJW, Frolow F. Fine-structural variance of family 3 carbohydrate-binding modules as extracellular biomass-sensing components of Clostridium thermocellum anti-σI factors. ACTA ACUST UNITED AC 2014; 70:522-34. [PMID: 24531486 DOI: 10.1107/s139900471302926x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 10/23/2013] [Indexed: 11/11/2022]
Abstract
The anaerobic, thermophilic, cellulosome-producing bacterium Clostridium thermocellum relies on a variety of carbohydrate-active enzymes in order to efficiently break down complex carbohydrates into utilizable simple sugars. The regulation mechanism of the cellulosomal genes was unknown until recently, when genomic analysis revealed a set of putative operons in C. thermocellum that encode σI factors (i.e. alternative σ factors that control specialized regulon activation) and their cognate anti-σI factor (RsgI). These putative anti-σI-factor proteins have modules that are believed to be carbohydrate sensors. Three of these modules were crystallized and their three-dimensional structures were solved. The structures show a high overall degree of sequence and structural similarity to the cellulosomal family 3 carbohydrate-binding modules (CBM3s). The structures of the three carbohydrate sensors (RsgI-CBM3s) and a reference CBM3 are compared in the context of the structural determinants for the specificity of cellulose and complex carbohydrate binding. Fine structural variations among the RsgI-CBM3s appear to result in alternative substrate preferences for each of the sensors.
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Affiliation(s)
- Oren Yaniv
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Galit Fichman
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ilya Borovok
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Yuval Shoham
- Department of Biotechnology and Food Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Edward A Bayer
- Department of Biological Chemistry, The Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Linda J W Shimon
- Department of Chemical Research Support, The Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Felix Frolow
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
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Role of transcription and enzyme activities in redistribution of carbon and electron flux in response to N2 and H2 sparging of open-batch cultures of Clostridium thermocellum ATCC 27405. Appl Microbiol Biotechnol 2014; 98:2829-40. [DOI: 10.1007/s00253-013-5500-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 12/18/2013] [Accepted: 12/24/2013] [Indexed: 12/17/2022]
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Xu T, Li Y, He Z, Zhou J. Dockerin-containing protease inhibitor protects key cellulosomal cellulases from proteolysis inClostridium cellulolyticum. Mol Microbiol 2014; 91:694-705. [DOI: 10.1111/mmi.12488] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Tao Xu
- Institute for Environmental Genomics; University of Oklahoma; Norman OK 73071 USA
- Department of Microbiology and Plant Biology; University of Oklahoma; Norman OK 73071 USA
| | - Yongchao Li
- Institute for Environmental Genomics; University of Oklahoma; Norman OK 73071 USA
- Department of Microbiology and Plant Biology; University of Oklahoma; Norman OK 73071 USA
| | - Zhili He
- Institute for Environmental Genomics; University of Oklahoma; Norman OK 73071 USA
- Virtual Institute for Microbial Stress and Survival; Berkeley USA
| | - Jizhong Zhou
- Institute for Environmental Genomics; University of Oklahoma; Norman OK 73071 USA
- Virtual Institute for Microbial Stress and Survival; Berkeley USA
- Earth Sciences Division; Lawrence Berkeley National Laboratory; Berkeley CA 94720 USA
- Department of Environmental Science and Engineering; Tsinghua University; Beijing 100084 China
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Linville JL, Rodriguez M, Land M, Syed MH, Engle NL, Tschaplinski TJ, Mielenz JR, Cox CD. Industrial robustness: understanding the mechanism of tolerance for the Populus hydrolysate-tolerant mutant strain of Clostridium thermocellum. PLoS One 2013; 8:e78829. [PMID: 24205326 PMCID: PMC3804516 DOI: 10.1371/journal.pone.0078829] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 09/16/2013] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND An industrially robust microorganism that can efficiently degrade and convert lignocellulosic biomass into ethanol and next-generation fuels is required to economically produce future sustainable liquid transportation fuels. The anaerobic, thermophilic, cellulolytic bacterium Clostridium thermocellum is a candidate microorganism for such conversions but it, like many bacteria, is sensitive to potential toxic inhibitors developed in the liquid hydrolysate produced during biomass processing. Microbial processes leading to tolerance of these inhibitory compounds found in the pretreated biomass hydrolysate are likely complex and involve multiple genes. METHODOLOGY/PRINCIPAL FINDINGS In this study, we developed a 17.5% v/v Populus hydrolysate tolerant mutant strain of C. thermocellum by directed evolution. The genome of the wild type strain, six intermediate population samples and seven single colony isolates were sequenced to elucidate the mechanism of tolerance. Analysis of the 224 putative mutations revealed 73 high confidence mutations. A longitudinal analysis of the intermediate population samples, a pan-genomic analysis of the isolates, and a hotspot analysis revealed 24 core genes common to all seven isolates and 8 hotspots. Genetic mutations were matched with the observed phenotype through comparison of RNA expression levels during fermentation by the wild type strain and mutant isolate 6 in various concentrations of Populus hydrolysate (0%, 10%, and 17.5% v/v). CONCLUSION/SIGNIFICANCE The findings suggest that there are multiple mutations responsible for the Populus hydrolysate tolerant phenotype resulting in several simultaneous mechanisms of action, including increases in cellular repair, and altered energy metabolism. To date, this study provides the most comprehensive elucidation of the mechanism of tolerance to a pretreated biomass hydrolysate by C. thermocellum. These findings make important contributions to the development of industrially robust strains of consolidated bioprocessing microorganisms.
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Affiliation(s)
- Jessica L Linville
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee, United States of America ; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
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Evaluation of Clostridium ljungdahlii DSM 13528 reference genes in gene expression studies by qRT-PCR. J Biosci Bioeng 2013; 116:460-4. [DOI: 10.1016/j.jbiosc.2013.04.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 04/08/2013] [Accepted: 04/08/2013] [Indexed: 11/19/2022]
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Bae J, Morisaka H, Kuroda K, Ueda M. Cellulosome complexes: natural biocatalysts as arming microcompartments of enzymes. J Mol Microbiol Biotechnol 2013; 23:370-8. [PMID: 23920499 DOI: 10.1159/000351358] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cellulose, a primary component of lignocellulosic biomass, is the most abundant carbohydrate polymer in nature. Only a limited number of microorganisms are known to degrade cellulose, which is highly recalcitrant due to its crystal structure. Anaerobic bacteria efficiently degrade cellulose by producing cellulosomes, which are complexes of cellulases bound to scaffoldins. The underlying mechanisms that are responsible for the assembly and efficiency of cellulosomes are not yet fully understood. The cohesin-dockerin specificity has been extensively studied to understand cellulosome assembly. Moreover, the recent progress in proteomics has enabled integral analyses of the growth-substrate-dependent variations in cellulosomal systems. Furthermore, the proximity and targeting effects of cellulosomal synergistic actions have been investigated using designed minicellulosomes. The recent findings about cellulosome assembly, strategies for optimal cellulosome production, and beneficial features of cellulosomes as an arming microcompartment on the microbial cell surface are summarized here.
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Affiliation(s)
- Jungu Bae
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
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Vodovnik M, Duncan SH, Reid MD, Cantlay L, Turner K, Parkhill J, Lamed R, Yeoman CJ, Miller MEB, White BA, Bayer EA, Marinšek-Logar R, Flint HJ. Expression of cellulosome components and type IV pili within the extracellular proteome of Ruminococcus flavefaciens 007. PLoS One 2013; 8:e65333. [PMID: 23750253 PMCID: PMC3672088 DOI: 10.1371/journal.pone.0065333] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 04/24/2013] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Ruminococcus flavefaciens is an important fibre-degrading bacterium found in the mammalian gut. Cellulolytic strains from the bovine rumen have been shown to produce complex cellulosome structures that are associated with the cell surface. R. flavefaciens 007 is a highly cellulolytic strain whose ability to degrade dewaxed cotton, but not Avicel cellulose, was lost following initial isolation in the variant 007S. The ability was recovered after serial subculture to give the cotton-degrading strain 007C. This has allowed us to investigate the factors required for degradation of this particularly recalcitrant form of cellulose. METHODOLOGY/PRINCIPAL FINDINGS The major proteins associated with the bacterial cell surface and with the culture supernatant were analyzed for R. flavefaciens 007S and 007C grown with cellobiose, xylan or Avicel cellulose as energy sources. Identification of the proteins was enabled by a draft genome sequence obtained for 007C. Among supernatant proteins a cellulosomal GH48 hydrolase, a rubrerthyrin-like protein and a protein with type IV pili N-terminal domain were the most strongly up-regulated in 007C cultures grown on Avicel compared with cellobiose. Strain 007S also showed substrate-related changes, but supernatant expression of the Pil protein and rubrerythrin in particular were markedly lower in 007S than in 007C during growth on Avicel. CONCLUSIONS/SIGNIFICANCE This study provides new information on the extracellular proteome of R. flavefaciens and its regulation in response to different growth substrates. Furthermore it suggests that the cotton cellulose non-degrading strain (007S) has altered regulation of multiple proteins that may be required for breakdown of cotton cellulose. One of these, the type IV pilus was previously shown to play a role in adhesion to cellulose in R. albus, and a related pilin protein was identified here for the first time as a major extracellular protein in R. flavefaciens.
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Affiliation(s)
- Maša Vodovnik
- Chair for Microbiology and Microbial Biotechnology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Sylvia H. Duncan
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Martin D. Reid
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Louise Cantlay
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
| | - Keith Turner
- Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | | | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, Israel
| | - Carl J. Yeoman
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Margret E. Berg. Miller
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Bryan A. White
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Edward A. Bayer
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Romana Marinšek-Logar
- Chair for Microbiology and Microbial Biotechnology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Harry J. Flint
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom
- * E-mail: .
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Higgins SR, Lopez RJ, Pagaling E, Yan T, Cooney MJ. Towards a hybrid anaerobic digester-microbial fuel cell integrated energy recovery system: an overview of the development of an electrogenic biofilm. Enzyme Microb Technol 2013; 52:344-51. [PMID: 23608503 DOI: 10.1016/j.enzmictec.2013.02.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 02/26/2013] [Accepted: 02/26/2013] [Indexed: 10/27/2022]
Abstract
An electrogenic biofilm was developed on a macroporous chitosan-carbon nanotube (CHIT-CNT) electrode under constant poised potential (-0.25V versus Ag/AgCl reference electrode) and flow through conditions utilizing the effluent of an anaerobic digester as both the inoculant and substrate for the electrogenic biofilm. After 125 days of inoculation the bioelectrode demonstrated an open circuit potential of -0.62V and a current density of 9.43μAcm(-3) (at -0.25V). Scanning electron microscopy images indicate thorough surface coverage of the biofilm with a high density of bacterial nanowires physically connecting bacteria to bacteria and bacteria to carbon nanotube (electrode surface) suggesting the nanowires are electrically conductive. DGGE was used to identify the major bacterial and archaeal populations.
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Affiliation(s)
- Scott R Higgins
- 1680 East West Rd., POST 109, Hawaii Natural Energy Institute, University of Hawaii, Honolulu HI 96822, United States.
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Carere CR, Rydzak T, Verbeke TJ, Cicek N, Levin DB, Sparling R. Linking genome content to biofuel production yields: a meta-analysis of major catabolic pathways among select H2 and ethanol-producing bacteria. BMC Microbiol 2012; 12:295. [PMID: 23249097 PMCID: PMC3561251 DOI: 10.1186/1471-2180-12-295] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/12/2012] [Indexed: 12/16/2022] Open
Abstract
Background Fermentative bacteria offer the potential to convert lignocellulosic waste-streams into biofuels such as hydrogen (H2) and ethanol. Current fermentative H2 and ethanol yields, however, are below theoretical maxima, vary greatly among organisms, and depend on the extent of metabolic pathways utilized. For fermentative H2 and/or ethanol production to become practical, biofuel yields must be increased. We performed a comparative meta-analysis of (i) reported end-product yields, and (ii) genes encoding pyruvate metabolism and end-product synthesis pathways to identify suitable biomarkers for screening a microorganism’s potential of H2 and/or ethanol production, and to identify targets for metabolic engineering to improve biofuel yields. Our interest in H2 and/or ethanol optimization restricted our meta-analysis to organisms with sequenced genomes and limited branched end-product pathways. These included members of the Firmicutes, Euryarchaeota, and Thermotogae. Results Bioinformatic analysis revealed that the absence of genes encoding acetaldehyde dehydrogenase and bifunctional acetaldehyde/alcohol dehydrogenase (AdhE) in Caldicellulosiruptor, Thermococcus, Pyrococcus, and Thermotoga species coincide with high H2 yields and low ethanol production. Organisms containing genes (or activities) for both ethanol and H2 synthesis pathways (i.e. Caldanaerobacter subterraneus subsp. tengcongensis, Ethanoligenens harbinense, and Clostridium species) had relatively uniform mixed product patterns. The absence of hydrogenases in Geobacillus and Bacillus species did not confer high ethanol production, but rather high lactate production. Only Thermoanaerobacter pseudethanolicus produced relatively high ethanol and low H2 yields. This may be attributed to the presence of genes encoding proteins that promote NADH production. Lactate dehydrogenase and pyruvate:formate lyase are not conducive for ethanol and/or H2 production. While the type(s) of encoded hydrogenases appear to have little impact on H2 production in organisms that do not encode ethanol producing pathways, they do influence reduced end-product yields in those that do. Conclusions Here we show that composition of genes encoding pathways involved in pyruvate catabolism and end-product synthesis pathways can be used to approximate potential end-product distribution patterns. We have identified a number of genetic biomarkers for streamlining ethanol and H2 producing capabilities. By linking genome content, reaction thermodynamics, and end-product yields, we offer potential targets for optimization of either ethanol or H2 yields through metabolic engineering.
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Affiliation(s)
- Carlo R Carere
- Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, Canada R3T 5V6
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Rydzak T, McQueen PD, Krokhin OV, Spicer V, Ezzati P, Dwivedi RC, Shamshurin D, Levin DB, Wilkins JA, Sparling R. Proteomic analysis of Clostridium thermocellum core metabolism: relative protein expression profiles and growth phase-dependent changes in protein expression. BMC Microbiol 2012; 12:214. [PMID: 22994686 PMCID: PMC3492117 DOI: 10.1186/1471-2180-12-214] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 09/11/2012] [Indexed: 01/21/2023] Open
Abstract
Background Clostridium thermocellum produces H2 and ethanol, as well as CO2, acetate, formate, and lactate, directly from cellulosic biomass. It is therefore an attractive model for biofuel production via consolidated bioprocessing. Optimization of end-product yields and titres is crucial for making biofuel production economically feasible. Relative protein expression profiles may provide targets for metabolic engineering, while understanding changes in protein expression and metabolism in response to carbon limitation, pH, and growth phase may aid in reactor optimization. We performed shotgun 2D-HPLC-MS/MS on closed-batch cellobiose-grown exponential phase C. thermocellum cell-free extracts to determine relative protein expression profiles of core metabolic proteins involved carbohydrate utilization, energy conservation, and end-product synthesis. iTRAQ (isobaric tag for relative and absolute quantitation) based protein quantitation was used to determine changes in core metabolic proteins in response to growth phase. Results Relative abundance profiles revealed differential levels of putative enzymes capable of catalyzing parallel pathways. The majority of proteins involved in pyruvate catabolism and end-product synthesis were detected with high abundance, with the exception of aldehyde dehydrogenase, ferredoxin-dependent Ech-type [NiFe]-hydrogenase, and RNF-type NADH:ferredoxin oxidoreductase. Using 4-plex 2D-HPLC-MS/MS, 24% of the 144 core metabolism proteins detected demonstrated moderate changes in expression during transition from exponential to stationary phase. Notably, proteins involved in pyruvate synthesis decreased in stationary phase, whereas proteins involved in glycogen metabolism, pyruvate catabolism, and end-product synthesis increased in stationary phase. Several proteins that may directly dictate end-product synthesis patterns, including pyruvate:ferredoxin oxidoreductases, alcohol dehydrogenases, and a putative bifurcating hydrogenase, demonstrated differential expression during transition from exponential to stationary phase. Conclusions Relative expression profiles demonstrate which proteins are likely utilized in carbohydrate utilization and end-product synthesis and suggest that H2 synthesis occurs via bifurcating hydrogenases while ethanol synthesis is predominantly catalyzed by a bifunctional aldehyde/alcohol dehydrogenase. Differences in expression profiles of core metabolic proteins in response to growth phase may dictate carbon and electron flux towards energy storage compounds and end-products. Combined knowledge of relative protein expression levels and their changes in response to physiological conditions may aid in targeted metabolic engineering strategies and optimization of fermentation conditions for improvement of biofuels production.
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Affiliation(s)
- Thomas Rydzak
- Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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Mearls EB, Izquierdo JA, Lynd LR. Formation and characterization of non-growth states in Clostridium thermocellum: spores and L-forms. BMC Microbiol 2012; 12:180. [PMID: 22897981 PMCID: PMC3438076 DOI: 10.1186/1471-2180-12-180] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 07/03/2012] [Indexed: 11/11/2022] Open
Abstract
Background Clostridium thermocellum is an anaerobic thermophilic bacterium that exhibits high levels of cellulose solublization and produces ethanol as an end product of its metabolism. Using cellulosic biomass as a feedstock for fuel production is an attractive prospect, however, growth arrest can negatively impact ethanol production by fermentative microorganisms such as C. thermocellum. Understanding conditions that lead to non-growth states in C. thermocellum can positively influence process design and culturing conditions in order to optimize ethanol production in an industrial setting. Results We report here that Clostridium thermocellum ATCC 27405 enters non-growth states in response to specific growth conditions. Non-growth states include the formation of spores and a L-form-like state in which the cells cease to grow or produce the normal end products of metabolism. Unlike other sporulating organisms, we did not observe sporulation of C. thermocellum in low carbon or nitrogen environments. However, sporulation did occur in response to transfers between soluble and insoluble substrates, resulting in approximately 7% mature spores. Exposure to oxygen caused a similar sporulation response. Starvation conditions during continuous culture did not result in spore formation, but caused the majority of cells to transition to a L-form state. Both spores and L-forms were determined to be viable. Spores exhibited enhanced survival in response to high temperature and prolonged storage compared to L-forms and vegetative cells. However, L-forms exhibited faster recovery compared to both spores and stationary phase cells when cultured in rich media. Conclusions Both spores and L-forms cease to produce ethanol, but provide other advantages for C. thermocellum including enhanced survival for spores and faster recovery for L-forms. Understanding the conditions that give rise to these two different non-growth states, and the implications that each has for enabling or enhancing C. thermocellum survival may promote the efficient cultivation of this organism and aid in its development as an industrial microorganism.
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Galisa PS, da Silva HAP, Macedo AVM, Reis VM, Vidal MS, Baldani JI, Simões-Araújo JL. Identification and validation of reference genes to study the gene expression in Gluconacetobacter diazotrophicus grown in different carbon sources using RT-qPCR. J Microbiol Methods 2012; 91:1-7. [PMID: 22814372 DOI: 10.1016/j.mimet.2012.07.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 07/03/2012] [Accepted: 07/03/2012] [Indexed: 12/30/2022]
Abstract
Gluconacetobacter diazotrophicus strain PAL5 is a nitrogen-fixing endophytic bacterium originally isolated from sugarcane and later on was found to colonize other plants such as rice, elephant grass, sweet potato, coffee, and pineapple. Currently, G. diazotrophicus has been considered a plant growth-promoting bacterium due to its characteristics of biological nitrogen fixation, phytohormone secretion, solubilization of mineral nutrients and antagonism to phytopathogens. Reverse transcription followed by quantitative real-time polymerase chain reaction (RT-qPCR) is a method applied for the quantification of nucleic acids because of its specificity and high sensitivity. However, the decision about the reference genes suitable for data validation is still a major issue, especially for nitrogen-fixing bacteria. To evaluate and identify suitable reference genes for gene expression normalization in the diazotrophic G. diazotrophicus, mRNA levels of fourteen candidate genes (rpoA, rpoC, recA, rpoD, fabD, gmk, recF, rho, ldhD, gyrB, gyrBC, dnaG, lpxC and 23SrRNA) and three target genes (matE, omp16 and sucA) were quantified by RT-qPCR after growing the bacteria in different carbon sources. The geNorm and Normfinder programs were used to calculate the expression stabilities. The analyses identified three genes, rho, 23SrRNA and rpoD, whose expressions were stable throughout the growth of strain PAL5 in the chosen carbon sources. In conclusion our results strongly suggest that these three genes are suitable to be used as reference genes for real-time RT-qPCR data normalization in G. diazotrophicus.
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Affiliation(s)
- Péricles S Galisa
- Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, Brazil
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Tracy BP, Jones SW, Fast AG, Indurthi DC, Papoutsakis ET. Clostridia: the importance of their exceptional substrate and metabolite diversity for biofuel and biorefinery applications. Curr Opin Biotechnol 2012; 23:364-81. [DOI: 10.1016/j.copbio.2011.10.008] [Citation(s) in RCA: 313] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/06/2011] [Accepted: 10/20/2011] [Indexed: 12/19/2022]
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Hauberg-Lotte L, Klingenberg H, Scharf C, Böhm M, Plessl J, Friedrich F, Völker U, Becker A, Reinhold-Hurek B. Environmental factors affecting the expression of pilAB as well as the proteome and transcriptome of the grass endophyte Azoarcus sp. strain BH72. PLoS One 2012; 7:e30421. [PMID: 22276194 PMCID: PMC3262810 DOI: 10.1371/journal.pone.0030421] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 12/15/2011] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Bacterial communication is involved in regulation of cellular mechanisms such as metabolic processes, microbe-host interactions or biofilm formation. In the nitrogen-fixing model endophyte of grasses Azoarcus sp. strain BH72, known cell-cell signaling systems have not been identified; however, the pilA gene encoding the structural protein of type IV pili that are essential for plant colonization appears to be regulated in a population density-dependent manner. METHODOLOGY/PRINCIPAL FINDINGS Our data suggest that pilAB expression is affected by population density, independent of autoinducers typical for gram-negative bacteria, likely depending on unknown secreted molecule(s) that can be produced by different bacterial species. We used transcriptomic and proteomic approaches to identify target genes and proteins differentially regulated in conditioned supernatants in comparison to standard growth conditions. Around 8% of the 3992 protein-coding genes of Azoarcus sp. and 18% of the detected proteins were differentially regulated. Regulatory proteins and transcription factors among the regulated proteins indicated a complex hierarchy. Differentially regulated genes and proteins were involved in processes such as type IV pili formation and regulation, metal and nutrient transport, energy metabolism, and unknown functions mediated by hypothetical proteins. Four of the newly discovered target genes were further analyzed and in general they showed regulation patterns similar to pilAB. The expression of one of them was shown to be induced in plant roots. CONCLUSION/SIGNIFICANCE This study is the first global approach to initiate characterization of cell density-dependent gene regulation mediated by soluble molecule(s) in the model endophyte Azoarcus sp. strain BH72. Our data suggest that the putative signaling molecule(s) are also produced by other Proteobacteria and might thus be used for interspecies communication. This study provides the foundation for the development of robust reporter systems for Azoarcus sp. to analyze mechanisms and molecules involved in the population-dependent gene expression in this endophyte in future.
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Affiliation(s)
- Lena Hauberg-Lotte
- University Bremen, Molecular Plant Microbiology, Center for Biomolecular Interactions Bremen, Bremen, Germany
| | - Hannah Klingenberg
- University Bremen, Molecular Plant Microbiology, Center for Biomolecular Interactions Bremen, Bremen, Germany
| | - Christian Scharf
- Ernst-Moritz-Arndt-University Greifswald, Interfaculty Institute of Genetics and Functional Genomics, Greifswald, Germany
- University of Medicine Greifswald, Department of Otorhinolaryngology, Greifswald, Germany
| | - Melanie Böhm
- University Bremen, Molecular Plant Microbiology, Center for Biomolecular Interactions Bremen, Bremen, Germany
| | - Jörg Plessl
- University Bremen, Molecular Plant Microbiology, Center for Biomolecular Interactions Bremen, Bremen, Germany
| | - Frauke Friedrich
- University Bremen, Molecular Plant Microbiology, Center for Biomolecular Interactions Bremen, Bremen, Germany
| | - Uwe Völker
- Ernst-Moritz-Arndt-University Greifswald, Interfaculty Institute of Genetics and Functional Genomics, Greifswald, Germany
| | - Anke Becker
- Institute of Biology III, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Barbara Reinhold-Hurek
- University Bremen, Molecular Plant Microbiology, Center for Biomolecular Interactions Bremen, Bremen, Germany
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Rydzak T, Levin DB, Cicek N, Sparling R. End-product induced metabolic shifts in Clostridium thermocellum ATCC 27405. Appl Microbiol Biotechnol 2011; 92:199-209. [DOI: 10.1007/s00253-011-3511-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 07/15/2011] [Accepted: 07/22/2011] [Indexed: 12/01/2022]
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Butanol production from crystalline cellulose by cocultured Clostridium thermocellum and Clostridium saccharoperbutylacetonicum N1-4. Appl Environ Microbiol 2011; 77:6470-5. [PMID: 21764954 DOI: 10.1128/aem.00706-11] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated butanol production from crystalline cellulose by cocultured cellulolytic Clostridium thermocellum and the butanol-producing strain, Clostridium saccharoperbutylacetonicum (strain N1-4). Butanol was produced from Avicel cellulose after it was incubated with C. thermocellum for at least 24 h at 60°C before the addition of strain N1-4. Butanol produced by strain N1-4 on 4% Avicel cellulose peaked (7.9 g/liter) after 9 days of incubation at 30°C, and acetone was undetectable in this coculture system. Less butanol was produced by cocultured Clostridium acetobutylicum and Clostridium beijerinckii than by strain N1-4, indicating that strain N1-4 was the optimal strain for producing butanol from crystalline cellulose in this coculture system.
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Raman B, McKeown CK, Rodriguez M, Brown SD, Mielenz JR. Transcriptomic analysis of Clostridium thermocellum ATCC 27405 cellulose fermentation. BMC Microbiol 2011; 11:134. [PMID: 21672225 PMCID: PMC3130646 DOI: 10.1186/1471-2180-11-134] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 06/14/2011] [Indexed: 01/18/2023] Open
Abstract
Background The ability of Clostridium thermocellum ATCC 27405 wild-type strain to hydrolyze cellulose and ferment the degradation products directly to ethanol and other metabolic byproducts makes it an attractive candidate for consolidated bioprocessing of cellulosic biomass to biofuels. In this study, whole-genome microarrays were used to investigate the expression of C. thermocellum mRNA during growth on crystalline cellulose in controlled replicate batch fermentations. Results A time-series analysis of gene expression revealed changes in transcript levels of ~40% of genes (~1300 out of 3198 ORFs encoded in the genome) during transition from early-exponential to late-stationary phase. K-means clustering of genes with statistically significant changes in transcript levels identified six distinct clusters of temporal expression. Broadly, genes involved in energy production, translation, glycolysis and amino acid, nucleotide and coenzyme metabolism displayed a decreasing trend in gene expression as cells entered stationary phase. In comparison, genes involved in cell structure and motility, chemotaxis, signal transduction and transcription showed an increasing trend in gene expression. Hierarchical clustering of cellulosome-related genes highlighted temporal changes in composition of this multi-enzyme complex during batch growth on crystalline cellulose, with increased expression of several genes encoding hydrolytic enzymes involved in degradation of non-cellulosic substrates in stationary phase. Conclusions Overall, the results suggest that under low substrate availability, growth slows due to decreased metabolic potential and C. thermocellum alters its gene expression to (i) modulate the composition of cellulosomes that are released into the environment with an increased proportion of enzymes than can efficiently degrade plant polysaccharides other than cellulose, (ii) enhance signal transduction and chemotaxis mechanisms perhaps to sense the oligosaccharide hydrolysis products, and nutrient gradients generated through the action of cell-free cellulosomes and, (iii) increase cellular motility for potentially orienting the cells' movement towards positive environmental signals leading to nutrient sources. Such a coordinated cellular strategy would increase its chances of survival in natural ecosystems where feast and famine conditions are frequently encountered.
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Affiliation(s)
- Babu Raman
- Biosciences Division, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831, USA
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Identification of cold-temperature-regulated genes in Flavobacterium psychrophilum. Appl Environ Microbiol 2011; 77:1593-600. [PMID: 21216906 DOI: 10.1128/aem.01717-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Flavobacterium psychrophilum is the etiological agent of bacterial coldwater disease (BCWD) and rainbow trout fry syndrome (RTFS). It causes disease primarily in fresh water-reared salmonids, but other fish species can also be affected. A diverse array of clinical conditions is associated with BCWD, including tail rot (peduncle disease), necrotic myositis, and cephalic osteochondritis. Degradation of connective and muscular tissues by extracellular proteases is common to all of these presentations. There are no effective vaccines to prevent BCWD or RTFS, and antibiotics are often used to prevent and control disease. To identify virulence factors that might permit development of an efficacious vaccine, cDNA suppression subtractive hybridization (SSH) was used to identify cold-regulated genes in a virulent strain of F. psychrophilum. Genes predicted to encode a two-component system sensor histidine kinase (LytS), an ATP-dependent RNA helicase, a multidrug ABC transporter permease/ATPase, an outer membrane protein/protective antigen OMA87, an M43 cytophagalysin zinc-dependent metalloprotease, a hypothetical protein, and four housekeeping genes were upregulated at 8°C versus the level of expression at 20°C. Because no F. psychrophilum gene was known to be suitable as an internal standard in reverse transcription-quantitative real-time PCR (RT-qPCR) experiments, the expression stability of nine commonly used reference genes was evaluated at 8°C and 20°C. Expression of the 16S rRNA was equivalent at both temperatures, and this gene was used in RT-qPCR experiments to verify the SSH findings. With the exception of the ATCC 49513 strain, similar patterns of gene expression were obtained with 11 other representative strains of F. psychrophilum.
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Global gene expression patterns in Clostridium thermocellum as determined by microarray analysis of chemostat cultures on cellulose or cellobiose. Appl Environ Microbiol 2010; 77:1243-53. [PMID: 21169455 DOI: 10.1128/aem.02008-10] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
A microarray study of chemostat growth on insoluble cellulose or soluble cellobiose has provided substantial new information on Clostridium thermocellum gene expression. This is the first comprehensive examination of gene expression in C. thermocellum under defined growth conditions. Expression was detected from 2,846 of 3,189 genes, and regression analysis revealed 348 genes whose changes in expression patterns were growth rate and/or substrate dependent. Successfully modeled genes included those for scaffoldin and cellulosomal enzymes, intracellular metabolic enzymes, transcriptional regulators, sigma factors, signal transducers, transporters, and hypothetical proteins. Unique genes encoding glycolytic pathway and ethanol fermentation enzymes expressed at high levels simultaneously with previously established maximal ethanol production were also identified. Ranking of normalized expression intensities revealed significant changes in transcriptional levels of these genes. The pattern of expression of transcriptional regulators, sigma factors, and signal transducers indicates that response to growth rate is the dominant global mechanism used for control of gene expression in C. thermocellum.
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