2025, Vol. 8, Issue 1, Part E

author(s)
Nisha Tak and Hukam S Gehlot

abstract
In the alkaline soils of the Indian Thar Desert, traditional rhizobial genera like Sinorhizobium/Ensifer and Bradyrhizobium nodulate wild legumes like Tephrosia species. Other root nodule bacterial endophytes isolated from Tephrosia spp. included members of Agrobacterium, Enterobacter, Cronobacter, Pseudomonas, Bacillus and Phyllobacterium. The predominant non-symbiotic endophytic bacteria were phenotypically and genetically diverse strains of Enterobacter (JNVU TF1, JNVU TF6, JNVU TF11, JNVU TF18, JNVU TF19, JNVU TW3, JNVU TW4 and JNVU TW6) which could tolerate high salt concentrations of up to 3%, grew at a broad pH range of 4.5–11, metabolized multiple sugars as sole carbon source and were resistant to multiple antibiotics demonstrating their robust metabolic profile. These fast-growing strains based on 16S rRNA gene shared similarities with Enterobacter cloacae sub sp. cloacae ATCC 13047T and Enterobacter cloacae sub sp. dissolvens LMG 2683T. Phylogenetically strains JNVU TW3 and JNVU TW4 formed a separate clade within Enterobacter species. These non-nodulating strains showed Plant Growth Promoting (PGP) traits such as ammonia production, solubilization of tricalcium phosphates and few could even efficiently mineralize phytate, the organic form of phosphate. Few strains showed chitinase activity and therefore such strains may exhibit antagonistic activity towards fungal plant pathogens. Our results demonstrate coexistence of non-rhizobia. Enterobacter strains showing good PGP attributes along with genetically diverse novel nodulating rhizobia within root nodules of Tephrosia spp.