Isolation, Screening and Evaluation of Multifunctional Strains of High Efficient Phosphate Solubilizing Microbes from Rhizosphere Soil

Phosphorus is one of the essential macronutrients which supports plant growth and is obtained from the soil.
Phosphate solubilizing micro-organisms helps in solubilizing the insoluble form of phosphates into soluble forms. The present study is aimed to isolate phosphate solubilizing microorganisms from rhizosphere of four plants. P-solubilizing organisms were screened using the Pikovskaya’s medium with Tricalcium phosphate as the sole source of phosphate. P-solubilization activity was measured in NBRIP medium and two fungal and bacterial strains obtained from the Colocasia esculenta were selected for their maximum solubilization indices. The selected strains were subjected for morphological, biochemical and genotypic identification and the strains were identified to be Pestalotiopsis microspora, Aquabacterium commune, Bacillus spp., and Aspergillus spp. All the identified strains were subjected to screening against various environmental stresses such as salinity, pH and temperatures. The strains were also tested for intrinsic antibiotic resistance. Finally, the strains were tested for the pesticide tolerance activity against 0.25% Cypermethrin. From these tests, it was observed that the strains were tolerant to salt concentration upto 4%, to temperature upto 37oC. and to pH of 7.8. The strains were tested for the indole acetic acid production activity and were found to be positive for the test. The strains were found to resistant against all the antibiotics except Gentamicin and Co-Trimoxazole. It was also found that the strains were tolerant towards the 0.25% Cypermethrin upto 1g/L. The identified strains were further analyzed by the
molecular studies and constructed phylogenetic tree analysis.