Plant growth promoting traits of bacteria isolated from organic inputs

Organic inputs such as vermiwash, biosol, cow urine, fermented butter milk, panchgavya, matka khad, cow pat pit and biodynamic compost were streaked on potato dextrose agar and nutrient agar media and incubated. A total of 92 bacterial isolates showing antibacterial activity were identified and purified by single spore isolation method. Among these, 12 isolates exhibited antifungal activity, and were also tested for plant growth promoting traits viz, phosphate solubilization, siderophore and indole acetic acid (IAA) production, ammonia production, proteolytic and nitrogenase enzyme activity. Six (AV5_B1, AB8_B2, AV10_A2, AP12_B3, AP18_S and AC20_A3) out of 12 isolates were selected as efficient phosphate solubilizers on the basis of qualitative assay. Maximum solubilisation was shown by AB8_B2 (365.22 ìg P/ml) and AV5_B1 (347.44 ìg P/ml) and 143.00 – 338.55 ìg P/ml solubilized by rest of the bacterial isolates quantitatively. All the bacterial isolates exhibited IAA and ammonia production. Maximum IAA was produced by AM16_P2 (52.59 ìg IAA/ml). Six isolates namely AV 5_B1, AP12_B3, AP13_B4, AP18_S, AC20_A3 and AP21_B6 formed orange zone (11.50 – 23.00 mm) on chrome azurol sulphonate (CAS) agar medium which depicted siderophore production. All the isolates except AM15_B5, AP18_S and AP21_B6 exhibited proteolytic activity with clear zone ranged between 6 – 12 mm. Nitrogenase enzyme activity was exhibited by AV 5_B1, AP9_A1 and AV10_A2.