Rhizobium-legume symbiosis is considered as the major contributor of biological nitrogen xation. In the present study, we have identi ed sigma factor 54regulated sRNAs from the genome of ve Rhizobium strains and integrated with the free-living and symbiotic speci c transcriptome data to identify the novel putative sRNAs that are over expressed during the regulation of nitrogen xation. A total of 1059 sRNAs were predicted from each genome of the select set of Rhizobium strains and 1,375 sRNAs were predicted from the transcriptome data of Bradyrhizobium japonicum. Target mRNA analysis revealed the functional role of putative novel sRNAs from different free-living and symbiotic strains. Those novel sRNAs were inferred to target several nodulation and nitrogen xation genes including nodC, nodJ, nodY, nodJ, nodM, nodW, nodZ, nifD, nifN, nifQ, xK, xL, Fdx, nolB, and several cytochrome proteins. Further, sRNAs of Bradyrhizobium japonicum which targeted the regulatory genes of nitrogen xation were experimentally con rmed with semi-quantitative reverse transcription polymerase chain reaction. Predicted target mRNAs were functionally classi ed based on the COG analysis and GO annotations. Studies on this sigma factor 54-regulated sRNA identi cation could be a better method to relate the role of sRNAs in nitrogen metabolism during free-living and symbiotic association with legumes.