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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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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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Abstract
Biomass conversion to ethanol as a liquid fuel by the thermophilic and anaerobic clostridia offers a potential partial solution to the problem of the world's dependence on petroleum for energy. Coculture of a cellulolytic strain and a saccharolytic strain of Clostridium on agricultural resources, as well as on urban and industrial cellulosic wastes, is a promising approach to an alternate energy source from an economic viewpoint. This review discusses the need for such a process, the cellulases of clostridia, their presence in extracellular complexes or organelles (the cellulosomes), the binding of the cellulosomes to cellulose and to the cell surface, cellulase genetics, regulation of their synthesis, cocultures, ethanol tolerance, and metabolic pathway engineering for maximizing ethanol yield.
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Affiliation(s)
- Arnold L Demain
- Charles A. Dana Research Institute for Scientists Emeriti, HS-330, Drew University, Madison, NJ 07940, USA.
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Knorr R, Ehrmann MA, Vogel RF. Cloning, expression, and characterization of acetate kinase from Lactobacillus sanfranciscensis. Microbiol Res 2002; 156:267-77. [PMID: 11716215 DOI: 10.1078/0944-5013-00114] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In the metabolism of Lactobacillus sanfranciscensis, the acetate kinase (AK) is a key enzyme and responsible for dephosphorylation of acetyl phosphate with the concomitant production of acetate and ATP. The L. sanfranciscensis ack gene was identified by PCR methods. It encodes a 397 amino acid protein sharing 56% similarity with Bacillus subtilis AK. Whereas cotranscription of ack and pta (phosphotransacetylase) is reported in previously characterised organisms, the L. sanfranciscensis ack gene is not located in direct neighbourhood to the encoding gene. AK was heterologously expressed in E. coli and characterised by its v(max) and Km values and by the dependence of enzyme activity on temperature and pH. Based on this data the in vivo role of the enzyme is discussed.
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Affiliation(s)
- R Knorr
- Institut für Technische Mikrobiologie, Technische Universität München, Freising-Weihenstephan, Germany
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