Project description:Isolation and characterization of two recently isolated Novosphingobium oxfordensis sp. nov. and Novosphingobium mississippiensis sp. nov. strains from soil, with LCMS and genome-based investigation of their glycosphingolipid productions
Project description:The ability of Bradyrhizobium japonicum and B. elkanii strains to utilize alkane and aromatic sulfonates as sole sources of sulfur for growth was investigated. All of the strains tested were able to utilize alkane sulfonates, but not aromatic sulfonates for growth. Whole-genome transcriptional profiling was used to assess B. japonicum USDA 110 genes involved in growth on alkane sulfonates, as compared to growth on sulfate and cysteine. Two sets of genes, bll7007 to bll7011 and bll6449 to 6456 were highly expressed during growth with sulfate and sulfonates. These genes were predicted to encode alkanesulfonate monooxygenases and ABC transporter components. Reverse transcription-PCR (RT-PCR) analyses showed that these genes were organized in two operon-like structures and expressed as polycistronic messages. The sulfonate monooxygenase encoded by bll7010 (ssuD) complemented an E. coli mutant defective in utilization of sulfonates. The expression of many genes that were induced during growth on cysteine and taurine were under the control of the FixLJ-FixK2-FixK1 symbiotic nitrogen fixation cascade, indicating there is a novel linkage between sulfur metabolism and nitrogen fixation. Taken together, results of this study indicate that Bradyrhizobium sp. strains are metabolically diverse and likely use organosulfur compounds for growth and survival, and for legume nodulation and nitrogen fixation in soil systems.
Project description:The ability of Bradyrhizobium japonicum and B. elkanii strains to utilize alkane and aromatic sulfonates as sole sources of sulfur for growth was investigated. All of the strains tested were able to utilize alkane sulfonates, but not aromatic sulfonates for growth. Whole-genome transcriptional profiling was used to assess B. japonicum USDA 110 genes involved in growth on alkane sulfonates, as compared to growth on sulfate and cysteine. Two sets of genes, bll7007 to bll7011 and bll6449 to 6456 were highly expressed during growth with sulfate and sulfonates. These genes were predicted to encode alkanesulfonate monooxygenases and ABC transporter components. Reverse transcription-PCR (RT-PCR) analyses showed that these genes were organized in two operon-like structures and expressed as polycistronic messages. The sulfonate monooxygenase encoded by bll7010 (ssuD) complemented an E. coli mutant defective in utilization of sulfonates. The expression of many genes that were induced during growth on cysteine and taurine were under the control of the FixLJ-FixK2-FixK1 symbiotic nitrogen fixation cascade, indicating there is a novel linkage between sulfur metabolism and nitrogen fixation. Taken together, results of this study indicate that Bradyrhizobium sp. strains are metabolically diverse and likely use organosulfur compounds for growth and survival, and for legume nodulation and nitrogen fixation in soil systems. Three independent biological materials were prepared for sulfate or sulfonate supplemented cells. Total 12 arrays including dye swap were analyzed.
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.
