Proteomic analyses of the phase transition from acidogenesis to solventogenesis using solventogenic and non-solventogenic Clostridium acetobutylicum strains

Abstract

The fermentation carried out by the solvent-producing bacterium, Clostridium acetobutylicum, is characterized by two distinct phases: acidogenic and solventogenic phases. Understanding the cellular physiological changes occurring during the phase transition in clostridial fermentation is important for the enhanced production of solvents. To identify protein changes upon entry to stationary phase where solvents are typically produced, we herein analyzed the proteomic profiles of the parental wild type C. acetobutylicum strains, ATCC 824, the non-solventogenic strain, M5 that has lost the solventogenic megaplasmid pSOL1, and the synthetic simplified alcohol forming strain, M5 (pIMP1E1AB) expressing plasmid-based CoA-transferase (CtfAB) and aldehyde/alcohol dehydrogenase (AdhE1). A total of 68 protein spots, corresponding to 56 unique proteins, were unambiguously identified as being differentially present after the phase transitions in the three C. acetobutylicum strains. In addition to changes in proteins known to be involved in solventogenesis (AdhE1 and CtfB), we identified significant alterations in enzymes involved in sugar transport and metabolism, fermentative pathway, heat shock proteins, translation, and amino acid biosynthesis upon entry into the stationary phase. Of these, four increased proteins (AdhE1, CAC0233, CtfB and phosphocarrier protein HPr) and six decreased proteins (butyrate kinase, ferredoxin:pyruvate oxidoreductase, phenylalanyl-tRNA synthetase, adenylosuccinate synthase, pyruvate kinase and valyl-tRNA synthetase) showed similar patterns in the two strains capable of butanol formation. Interestingly, significant changes of several proteins by post-translational modifications were observed in the solventogenic phase. The proteomic data from this study will improve our understanding on how cell physiology is affected through protein levels patterns in clostridia.

Complex and extensive post-transcriptional regulation revealed by integrative proteomic and transcriptomic analysis of metabolite stress response in Clostridium acetobutylicum

“…There have been nine, genome-scale proteomic studies on C. acetobutylicum , most of which were performed using two-dimensional gel electrophoresis combined with mass spectrometry (Table 8 ) [ 54 – 62 ]. Schaffer et al (2002) investigated the proteins that were induced during the solventogenic phase of fermentation and identified 86 proteins (52 upregulated and 34 downregulated, fold change ≥2) that had differential expression during solventogenesis [ 56 ].…”

Redox-switch regulatory mechanism of thiolase from Clostridium acetobutylicum

“…The stained gels were scanned by using an UMAX PowerLook 2100XL Scanner (UMAX Technologies, Inc., Dallas, TX, USA). Protein spots were identified by comparing with the proteome reference map of C. acetobutylicum reported previously 53 54 .…”

Metabolic engineering of clostridia for the production of chemicals

“…The letters G, R, and M in the in silico model represents the number of genes, reactions, and metabolites, respectively. The corresponding reference is indicated at the end of strain's name. For online version, colors indicate as follows: light blue, C. acetobutylicum ; light orange, C. kluyveri ; light purple, C. cellulolyticum ; light green, C. beijerinckii ; light gray, Clostridium sp.…”