Understanding aerobic/anaerobic metabolism in Caldibacillus debilis through a comparison with model organisms |
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Authors: | Scott Wushke Victor Spicer Xiang Li Zhang Brian Fristensky Oleg V Krokhin David B Levin Nazim Cicek Richard Sparling |
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Institution: | 1. Department of Microbiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada;2. Department Physics & Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada;3. Department Plant Science, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada;4. Department of Internal Medicine & Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, Winnipeg, Manitoba R3E 3P4, Canada;5. Department of Biosystems Engineering, University of Manitoba, Winnipeg, Manitoba R3T 3V6, Canada |
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Abstract: | Caldibacillus debilis GB1 is a facultative anaerobe isolated from a thermophilic aero-tolerant cellulolytic enrichment culture. There is a lack of representative proteomes of facultative anaerobic thermophilic Bacillaceae, exploring aerobic/anaerobic expression. The C. debilis GB1 genome was sequenced and annotated, and the proteome characterized under aerobic and anaerobic conditions while grown on cellobiose. The draft sequence of C. debilis GB1 contains a 3,340,752 bp chromosome and a 5,386 bp plasmid distributed over 49 contigs. Two-dimensional liquid chromatography mass spectrometry/mass spectrometry was used with Isobaric Tags for Relative and Absolute Quantification (iTRAQ) to compare protein expression profiles, focusing on energy production and conversion pathways. Under aerobic conditions, proteins in glycolysis and pyruvate fermentation pathways were down-regulated. Simultaneously, proteins within the tricarboxylic acid cycle, pyruvate dehydrogenase, the electron transport chain, and oxygen scavenging pathways showed increased amounts. Under anaerobic conditions, protein levels in fermentation pathways were consistent with the generated end-products: formate, acetate, ethanol, lactate, and CO2. Under aerobic conditions CO2 and acetate production was consistent with incomplete respiration. Through a direct comparison with gene expression profiles from Escherichia coli, we show that global regulation of core metabolism pathways is similar in thermophilic and mesophilic facultative anaerobes of the Phylum Proteobacteria and Firmicutes. |
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Keywords: | Thermophilic Genomics Proteomics Mixed acids fermentation Respiration |
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