Bacterial endophytes prevalently colonize the internal tissues of plants and are shown to positively influence plant growth. They play a significant role in maximizing crop productivity while reducing the environmental impacts of agriculture. The aim of the present work was to isolate and characterize root nodule endophytes from two groundnut genotypes (Bunching & Semispreading). A total of 20 bacterial isolates were recovered from groundnut nodules using the yeast extract mannitol agar medium supplemented with congo red. The isolates were characterized morphologically, biochemically and compared with the reference strains Rhizobium sp. TNAU 14, Rhizobium sp. COS 1 and Bradyrhizobium sp. The isolates showed close similarity to the reference strains in their biochemical and morphological characteristics. Based on these results, it is concluded that the isolates YBB1, YBB6, YBB8, YBB14A, S27 from the bunching type and YSB 3, YSB4 and YSB5 from the semi-spreading genotype tentatively represent Rhizobium.
Key words : Groundnut, Isolation, Rhizobial endophytes, Rhizobium..