Sadam D. V. Satyanarayana1, M.S.R. Krishna1
and Pindi Pavan Kumar2*

1Department of Biotechnology, K L University, Green Fields, Vaddeswaram,
Guntur, Andhrapradesh, 522502, India.
2Department of Microbiology, Palamuru University, Mahbubnagar, India.

Abstract

Understanding the concept of symbiosis in a more localized natural selective way and optimizing for the yielding advantages of confined geography is the objective of the present study. To be more precise the aim of the study is the isolation and identification of crop specific Rhizobium strains for Arachis hypogaea from Bhadrachalam forest lands using physical, biochemical and in silico analysis. Soil samples were collected randomly from 45 different locations of Bhadrachalam forest and sown with groundnut seeds in triplets. The NPK and micronutrient levels of all the soil samples were found to be comparable. Five out of 45 samples which supported the best plant growth were taken for further investigations. Rhizobial strains from the root nodules of these five samples were isolated and maintained in pure cultures. Broths of each pure culture were inoculated on the seeds sown in sterile soil and controls were maintained. The results showed that the inoculated Rhizobia tremendously improved the plant growth when compared with control. Further phylogenetic analysis revealed that the contributing organisms were Rhizobium leguminosarum, Rhizobium trifolii, Rhizobium meliloti, Rhizobium phaseoli and Bradyrhizobium japonicum. These Rhizobial species in the pure form exhibited high rate of plant growth at lab conditions followed by improved growth in low vegetative agriculture soils of the same geography. The 16S rRNA gene sequencing revealed the fact that soil sample S3 contains abundant R. leguminosarum sp., with 99% similarity. The sample 1, 2, 4 and 5 contain abundant levels of R. trifolii, R. meliloti, R. phaseoli and B. japonicum respectively. Furthermore in silico analysis of Nif A protein revealed the underlining precursors of IAA production and nitrogenase activity. Therefore this method could be adopted for easy identification of species specific rhizobium in targeted geographies.

Keywords: Rhizobacteria; Nif A; Nitrogen fixation; Indole acetic acid; Geogrphy; Arachis hypogaea