Project description:The purpose of the study is to identify Irr-responsive genes in the bacterium Bradyrhizobium japonicum. Parent strain LO was compared to irr mutant strain LODTM5 by whole genome microarray analysis. Both cell types were grown in iron-limited media. Keywords: Comparison of B. japonicum wild type and mutant cells
Project description:Investigation of whole genome gene expression level in motile strain of Sphingomonas. sp A1 All flagellar genes in motile strain of Sphingomonas. sp A1 are highly transcribed.
Project description:Nodule-forming bacteria play crucial roles in plant health and nutrition by fixing atmospheric nitrogen. Despite the importance of this relationship, how nodule-forming bacteria are affected by plant exudates and soil minerals is not fully characterized. Of particular interest are the effects of plant-derived methanol and lanthanide metals on the growth of nitrogen-fixing Rhizobiales. Prior work has demonstrated that select Bradyrhizobium are able to assimilate methanol only in the presence of lanthanide metals; however, the pathway enabling assimilation remains unknown. Here we characterize Bradyrhizobium sp. USDA 3456 to determine the pathways involved in methanol metabolism. Based on genomic analyses, we hypothesized that methanol assimilation in these organisms occurs via the lanthanide-dependent methanol dehydrogenase XoxF, followed by oxidation of formaldehyde via the glutathione-linked oxidation pathway, subsequent oxidation of formate via formate dehydrogenases, and finally assimilation of CO2 via the Calvin Benson Bassham (CBB) pathway. Transcriptomics revealed upregulation of the aforementioned pathways in Bradyrhizobium sp. USDA 3456 during growth on methanol. Assays demonstrated increased activity of the glutathione-linked oxidation pathway and formate dehydrogenases during growth on methanol compared to succinate. 13C-labeling studies demonstrate the presence of CBB intermediates and label incorporation during growth on methanol. Our findings provide multiple lines of evidence supporting the proposed XoxF-CBB pathway and, combined with genomic analyses, suggest that this metabolism is widespread among Bradyrhizobium and Sinorhizobium species.
Project description:The purpose of the study is to identify iron-responsive genes in the bacterium Bradyrhizobium japonicum. Parent strain LO was grown under iron limitation or under iron sufficiency and compared to each other by whole genome microarray analysis. Keywords: Comparison of cells grown under low or high iron conditons
Project description:To circumvent the paucity of nitrogen sources in the soil Legume plants evolved a symbiotic interaction with nitrogen-fixing soil bacteria called rhizobia. During symbiosis, legumes form root organs called nodules, where bacteria are housed intracellularly and become active nitrogen fixers known as bacteroids. Depending on their host plant, bacteroids can adopt different morphotypes, being either unmodified (U), elongated (E) or spherical (S). E- and S-typr bacteroids undergo a terminal differentiation leading to irreversible morphological changes and DNA endoreduplication. Previous studies suggest that differentiated bacteroids display an increased symbiotic efficiency (E>U & S>U). In this study, we used a combination of Aeschynomene species inducing E- and S-type bacteroids in symbiosis with Bradyrhizobium sp. ORS285 to show that S- performed better than E-type bacteroids. Thus, we performed a transcriptomic analysis on E- and S-type bacteroids to identify the bacterial functions involved in each bacteroid type.
