Isolation of Phosphorus Solubilizing Bacteria from Mangrove Rhizospheric Sediment and its Potential Application in Aquaculture

Background: Phosphorus acts as a limiting nutrient in aquatic environments due to its non-availability as it forms insoluble precipitate with Ca, Mg, Fe and Al. Phosphorus solubilising bacteria (PSB) solubilizes the inorganic precipitate into soluble phosphorus. Methods: The PSB isolates were screened and isolated from rhizospheric sediment of mangrove, Avicennia marina of Ennore creek, Tamil Nadu. Their phosphorus transformation potential and the possibilities of their application in aquaculture to solubilize inorganic phosphorus were studied. Result: In the present study, thirteen nos. of PSB isolates were screened from the rhizospheric sediment samples of Avicennia marina collected from Ennore region and identified as Rhodococcus, Arthrobacter, Bacillus, Enterococcus, Staphylococcus and Pseudomonas. The P-solubilizing activity and Acid phosphatase (ACPase) activity of PSB isolates were found to be in the range of 7.62±0.51- 16.33±0.84 mg/l and 4.40±0.28 - 22.77±0.32 mmol ml-1 h-1 respectively. The maximum ACPase activity was exhibited by Arthrobacter sp (22.77±0.32 mmol ml-1 h-1) followed by Rhodococcus sp. (18.08±0.78 mmol ml-1 h-1). The P-mobilizing potential of the isolates obtained in this study were compared with the commercial product following a microcosm study for a period of 21 days. Rhodococcus sp showed higher ACPase activity in sediment (12.00 mmol g-1 h-1) than that of the commercial product (11.23 mmol g-1 h-1).