Phenotypic Characterisation of Rhizobial Strains Symbiotically Associated with Smithia Ciliata and Desmodium Polycarpum of Meghalaya

The present study focuses on the phenotypic characterisation of rhizobial strains isolated from the native legumes of Meghalaya. A total of seventy-five strains were isolated from various ecological regions, and sixteen strains from them were selected for further characterisation. It was observed that all sixteen rhizobial strains could not tolerate an alkaline pH value of 11. The majority of the fast-growing and slow-growing rhizobial strains in this investigation were found to have the highest temperature tolerance up to 40 ºC. It was also observed that all sixteen strains showed tolerance to different NaCl concentrations, and in the intrinsic antibiotic resistance test, the antibiotic Ampicillin (A10) was found to be highly effective in restricting the growth of the isolates, with only seven out of seventeen isolates being susceptible to this antibiotic. A total of eleven RNB isolates were found to be alkali-producing. It was observed that the rhizobial strain, NEHU-DP23, has the maximum number of fourteen sugars that were being utilised. The results revealed considerable phenotypic variability among the strains, indicating a broad adaptability to different environmental conditions.