Insight into Energy Conservation via Alternative Carbon Monoxide Metabolism in Carboxydothermus pertinax Revealed by Comparative Genome Analysis.

In this study, we used comparative genome analysis of the genus Carboxydothermus to show variations in the CO dehydrogenase/energy-converting hydrogenase gene cluster, which is responsible for CO metabolism with H2 production (hydrogenogenic CO metabolism). Indeed, ability or inability to produce H2 with CO oxidation is explained by the presence or absence of this gene cluster in C. hydrogenoformans, C. islandicus, and C. ferrireducens Interestingly, despite its hydrogenogenic CO metabolism, C. pertinax lacks the Ni-CO dehydrogenase catalytic subunit (CooS-I) and its transcriptional regulator encoding genes in this gene cluster probably due to inversion. Transcriptional analysis in C. pertinax showed that the Ni-CO dehydrogenase gene (cooS-II) and distantly encoded energy-converting hydrogenase related genes were remarkably upregulated under 100% CO. In addition, when thiosulfate was available as a terminal electron acceptor under 100% CO, C. pertinax maximum cell density and maximum specific growth rate were 3.1-fold and 1.5-fold higher, respectively, than when thiosulfate was absent. The amount of H2 produced was only 63% of the consumed CO, less than expected according to hydrogenogenic CO oxidation: CO + H2O → CO2 + H2 Accordingly, C. pertinax would couple CO oxidation by Ni-CO dehydrogenase-II with simultaneous reduction of not only H2O but thiosulfate when grown under 100% CO.IMPORTANCE Anaerobic hydrogenogenic carboxydotrophs are thought to fill a vital niche with sc...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research