Studies on biodiversity and bioprospecting of active mud volcano associated bacteria and actinobacteria from Baratang, Andaman Islands, India

Abstract

A total of 79 bacteria and 101 actinobacteria strains were isolated from the sediment samples of the different points of Baratang mud volcano viz., point of the eruption (M), middle of the volcano (MD), and the dried part of the mud volcano (E). Based on the biochemical and molecular characterization, the isolates were categorized under the phyla Proteobacteria, Firmicutes and Proteobacteria included representatives of Classes Alphaproteobacteria, Gammaproteobacteria and Deltaproteobacteria of 29 genera with 38 distinct ribotypes. Thirty-eight bacterial strains from four different regions of mud volcano revealed excellent activity for indole-3-acetic acid (IAA) production. Excellent antagonistic property, plant growth promoting properties such as IAA production, phosphate, potassium and zinc solubilization were identified in Bacillus megaterium NIOT_MV 31 strain of 38 studied isolates. In this study, we investigated the optimization of IAA production by B. megaterium NIOT_MV 31 and its formulation as a plant growth promoter to improve economic and agricultural development. Maximum IAA yield was achieved using optimal conditions (42.63 mg/mL) in the presence of optimized tryptophan after 4 days of incubation. Twofold increase in the plant growth parameters were observed to that of control plants. Optimization of culture conditions resulted in a fourfold increase in IAA production by B. megaterium NIOT_MV 31 cells. The results clearly demonstrated that, B. megaterium NIOT_MV 31 holds great potential as a source for IAA production and may be useful for commercial applications.