Project description:Trabulsiella guamensis is a nonpathogenic enterobacterium that was isolated from a vacuum cleaner on the island of Guam. It has one H2-oxidizing Hyd-2-type hydrogenase (Hyd) and encodes an H2-evolving Hyd that is most similar to the uncharacterized Escherichia coli formate hydrogenlyase (FHL-2 Ec ) complex. The T. guamensis FHL-2 (FHL-2 Tg ) complex is predicted to have 5 membrane-integral and between 4 and 5 cytoplasmic subunits. We showed that the FHL-2 Tg complex catalyzes the disproportionation of formate to CO2 and H2 FHL-2 Tg has activity similar to that of the E. coli FHL-1 Ec complex in H2 evolution from formate, but the complex appears to be more labile upon cell lysis. Cloning of the entire 13-kbp FHL-2 Tg operon in the heterologous E. coli host has now enabled us to unambiguously prove FHL-2 Tg activity, and it allowed us to characterize the FHL-2 Tg complex biochemically. Although the formate dehydrogenase (FdhH) gene fdhF is not contained in the operon, the FdhH is part of the complex, and FHL-2 Tg activity was dependent on the presence of E. coli FdhH. Also, in contrast to E. coli, T. guamensis can ferment the alternative carbon source cellobiose, and we further investigated the participation of both the H2-oxidizing Hyd-2 Tg and the H2-forming FHL-2 Tg under these conditions.IMPORTANCE Biological H2 production presents an attractive alternative for fossil fuels. However, in order to compete with conventional H2 production methods, the process requires our understanding on a molecular level. FHL complexes are efficient H2 producers, and the prototype FHL-1 Ec complex in E. coli is well studied. This paper presents the first biochemical characterization of an FHL-2-type complex. The data presented here will enable us to solve the long-standing mystery of the FHL-2 Ec complex, allow a first biochemical characterization of T. guamensis's fermentative metabolism, and establish this enterobacterium as a model organism for FHL-dependent energy conservation.
Project description:Phosphate-solubilizing bacteria (PSB) have the ability to dissolve insoluble phosphate and enhance soil fertility. However, the growth and mineral phosphate solubilization of PSB could be affected by exogenous soluble phosphate and the mechanism has not been fully understood. In the present study, the growth and mineral phosphate-solubilizing characteristics of PSB strain Burkholderia multivorans WS-FJ9 were investigated at six levels of exogenous soluble phosphate (0, 0.5, 1, 5, 10 and 20 mM). The WS-FJ9 strain showed better growth at high levels of soluble phosphate. The phosphate-solubilizing activity of WS-FJ9 reduced as the soluble phosphate concentration increased, as well as the production of pyruvic acid. Transcriptome profiling of WS-FJ9 at three levels of exogenous soluble phosphate (0, 5 and 20 mM) identified 446 differentially expressed genes, among which 44 genes were continuously up-regulated when soluble phosphate concentration increased and 81 genes were continuously down-regulated. Some genes related to cell growth were continuously up-regulated which would account for the better growth of WS-FJ9 at high levels of soluble phosphate. Genes involved in glucose metabolism, including glycerate kinase, 2-oxoglutarate dehydrogenase, and sugar ABC-type transporter were continuously down-regulated which indicates that metabolic channeling of glucose towards phosphorylative pathway was negatively regulated by soluble phosphate.
2017-01-20 | GSE93761 | GEO
Project description:Phosphorus-solubilizing bacteria in peanut geocarposphere