In Vitro biocontrol traits of rhizobacteria isolated from the coastal sand dune plants in Chennai, India

Coastal sand dunes (CSD) are one of the least explored marine ecosystems for beneficial microorganisms. As a small part of our ongoing continuous research on Bioprospecting of Microorganisms from the coastal sand dunes, a total of 40 rhizobacterial strains were isolated from the rhizosphere of coastal sand dune plant samples using Kings B Agar (KBA) medium. The isolated strains were screened for their antagonist activity against Rhizoctonia solani by using dual culture assay on Potato Dextrose Agar (PDA) medium. It has been found that among 40 bacterial strains, 14 exhibited antagonistic activity against R. solani. It has been found that a strain designated as Pseudomonas sp. AMET 6007 exhibited 32% control over Sheath blight pathogen of rice. These 14 antagonistic fluorescent pseudomonads were also characterized for their antagonistic mechanisms such as competition for iron (production of siderophores), production of volatile (hydrogen cyanide-HCN) and diffusible metabolites. They were also characterized for their ability to produce plant growth promotoing hormone, indole acetic acid (IAA). The results of the present study indicates that research is to be intensified to study the effect of these antagonists on sheath blight suppression at controlled and field conditions to ascertain their efficacy as biocontrol agents. Thus the study on the bacterial community isolation from the rhizosphere helps in revealing all the significant activities which can be used for Agricultural Biotechnology applications.