Trends in Biosciences

Interaction between soil microbes and minerals play a major role in environmental cycling processes, which leads to the mobilization of nutrients from soil components into available forms for biological uptake. Hence, the present investigation was focused to identify and characterize the bio-dissoluting bacteria, their dissolution potential. Rhizosphere soil samples were collected from 26 regions of Tamil Nadu. Potassium releasing bacterium was assessed by the production of clearing zone of solubilization and extracellular polysaccharide in plate assay. Among fifty one isolates tested ten isolates had both solubilizing zone and extra cellular polysaccharides (EPS) and four isolates produced only slimy extra cellular polysaccharides (EPS) and no zones in agar plates supplemented with potassium rich mineralin Alexandrovs’ medium. The maximum amount of IAA produced by the isolate KRB-9 was 22.2μg ml⁻¹ followed by KRB-1 which produced 18.8 μg ml⁻¹. The isolates were tested for their ability to solubilize silica and release inorganic K minerals viz., potassium alumino silicate and feldspar supplemented in Alexandrovs’ medium. KRB-9 significantly produced higher dissolution rate of 92.2 per cent followed by KRB1 with 81.1 per cent. 16S rRNA gene sequence homology and phylogeny construction have shown, the isolate KRB9 belongs to the genus Bacillus mucilaginosus which is now placed under the group Peanibacillus.