Genetic characterization and diversity of nitrogen fixing Rhizobium spp. isolated from root nodules of legumes

Abstract

The useful plant-growth-influencing bacteria are called PGPR. In this study, fifty bacterial isolates were collected from legume root nodules in Junagadh Agricultural University. Isolates can grow in various NaCl concentrations and pH 6-8. They were positive for nitrate reduction, glucose, arabinose production, and IAA production (1.726 to 3.206 at 535 nm), phosphate, potash, zinc solubilizing tests on 3, 5, 7, 9 DAI. Phosphate solubilization efficiency: 14.29-50.00%, 25.00-75.00%, 33.33-80.00%, 44.44-100.00% on 3, 5, 7, 9 DAI. Potash solubilization: 9.09-42.86%, 33.33-55.56% on 3, 9 DAI. Zinc solubilization: 11.11-71.43%, 30.00-88.89% on 3, 9 DAI. Nitrogen fixation: 1.85 to 4.25 mg ‘N’/g on Jensen’s agar. Isolates showcased hydroxymate type siderophore production, ACC-deaminase enzyme, melanin production. EPS production: 13.74 to 38.66 mg ml-1. Selected bacterial isolates identified by 16S rRNA gene analysis include 3 Rhizobium leguminosarum, 2 Rhizobium etli, and 5 others (Neorhizobium galegae, Rhizobium gallicum, Rhizobium giardinii, Rhizobium indigoferae, and Rhizobium mongolense). They exhibit nif and nod gene presence confirmed via PCR amplification.