Effect of different carbon, nitrogen and vitamine sources on exopolysaccharide production of Rhizobium species isolated from root nodule of redgram

Three bacterial strains CHRS-7, RAB-1 and RAN-1 were isolated from root nodules of redgram (Cajanus cajan) and identified as Rhizobium sp. based on 16S rDNA sequence homology and assigned accession number MH636329, MH636773 and MH541051, respectively by National Center for Biotechnology Information (NCBI). All the strains could produce copious amount of exopolysaccharides in yeast extract manitol broth medium. All the three strains had different stationary phases but the bacterial growth and exopolysaccharides production occurred simultaneously. The glucose (1.5 %), manitol (2.0%) and sucrose (1.5%) were the preferable carbon sources of CHRS-7, RAB-1 and RAN-1 respectively, for both growth and EPS production. Among the nitrogen sources glycine (0.1%), NaNO3 (0.1%) and KNO3 (0.1%) were the preferable N sources for CHRS-7, RAB-1 and RAN-1 respectively, whereas, CHRS-7, RAB-1 and RAN-1 preferred biotin 1.5%, 2.0% and 1%, respectively