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.