Isolation and Characterization of Rhizospheric Phosphate Solubilizing Bacteria from Wetland Paddy Field of Mizoram, India

A significant amount of bacterial species have a beneficial effect upon plant growth. The ability of phosphate solubilizing bacteria (PSB) to convert insoluble form of phosphorous to an available form is an important trait in plant growth promoting bacteria for increasing crop yield. Mostly they are associated with the plant rhizosphere, hence are called as rhizobacteria. A study was undertaken to isolate and characterize rhizospheric PSB population from wetland paddy field of North Vanlaiphai, Mizoram, India. The study of beneficial microorganisms especially from wetland paddy field in Mizoram, India is still in infancy and the present study is the initial phase of exploration of PSB in this region. For screening of the potential PSB, qualitative and quantitative P solubilizing efficiency was estimated using Pikovskaya medium containing tricalcium phosphate as the phosphorous source. Molecular and biochemical characterizations of the isolates were carried out. Upon Screening and molecular identification using 16SrRNA gene, 15 best p-solubilizers were selected for further studies. Since the main mechanism of P-solubilization seemed to be mediated by organic acid production, HPLC analysis revealed production of multiple organic acids such as gluconic oxalic, citric, tartaric, succinic, formic and acetic acid in the culture supernatant. The isolated strains were also capable of producing Indole Acetic Acid (IAA) and estimation of enzyme acid phosphatase was done. Based on partial sequence analysis of 16S rRNA genes, the 15 isolates were found to belong to the genera Bacillus, Burkholderia, Paenibacillus sp.