Acinetobacter sp. - An acid-tolerant phosphate solubilizing bacteria from lateritic soils
Authors: Athulya, M.M., K.Surendra Gopal* and D.Girija
Department of Agricultural Microbiology, College of Horticulture,
Kerala Agricultural University, Vellanikkara, Thrissur-680656
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A study was conducted to screen the isolates of phosphate solubilizing bacteria (PSB) ls, for efficiency and acid tolerance. The rhizosphere and non-rhizosphere soil samples were collected from various lateritic soils in Thrissur district of Kerala and phosphate solubilizing bacteria were isolated on Pikovskaya’s agar medium. Under in vitro conditions, the bacterial isolate PMD-7 (Acinetobacter sp.) solubilized 207.2 ug/ml of insoluble phosphorus. Its solubilization efficiency in Pikovskaya’s agar medium was 247.62%. It grew in the pH range of 4.0 to 7.0 and tolerated upto pH 3.5. When it was grown in Pikovskaya’s broth, it showed a reduction in pH from pH 7.0 to 4.35 indicating the production of organic acids, which is one of the mechanism involved in ‘P’ solubilization by microbes. The bacterial isolate also produced 33ug/ml of indole acetic acid (IAA) which is a phytohormone for the plant growth. The molecular characterization using 16s rDNA sequencing revealed the identity of bacteria as Acinetobacter sp. However, this new acid-tolerant PSB is the first report from Kerala, which could be a potential biofertilizer for acidic soils of Kerala.

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I am an agricultural scientist specialized in Agricultural Microbiology