Characterization of mineral phosphate solubilizing and plant growth promoting bacteria from termite soil of arid region.

Five highly efficient phosphate solubilizing bacteria, viz., sp. A3, sp. A34, sp. A37, sp. B7 and sp. AH9 were isolated from termitorial soils of Sanjivani island of southern Maharashtra, India. These isolates were characterized and explored for phosphate solubilization and plant growth promotion. Among these, sp. AH9 showed highest phosphate solubilization index (3.5) and solubilization efficiency (250%) on Pikovskaya agar. Interestingly, sp. A34 displayed maximum mineral phosphate solubilization (1072.35 mg/L) in liquid medium and during this period the pH dropped to 3.13. All five isolates had highest P solubilization at 48 h after inoculation. During mineral phosphate solubilization, both gluconic acid and 2-keto gluconic acid were produced by and isolates, while only 2-keto gluconic acid was detected in isolates. Highest organic acid (39.07 ± 0.04 g/L) production was envisaged in sp. AH9, while sp. A34 produced the least amount (13.00 ± 0.01 g/L) of organic acid. Seed bacterization with sp. A3 and sp. A37 resulted in ~ 37% and ~ 53% increase in root length of tomato seedlings, respectively, while sp. A34 and sp. B7 had deleterious effects on root length as well as overall growth of the seedlings. To our knowledge, this is the first report of plant growth promoting potential of microorganisms isolated from termitorial soil of Sanjivani island, which is a drought-prone area. Therefore, such efficient growth promoting P solubilizers can offer an effective solution for sustainable agriculture in arid, dryland farming and drought-prone regions.