Abstract:[Background] Acinetobacter indicus JL-1 can convert the insoluble phosphorus into soluble phosphate, which can be absorbed by plants, but the mechanism has not been known clearly. [Objective] Acinetobacter indicus JL-1 was used to study the mechanism of phosphate solubilization primarily. [Methods] To determine the optimal phosphorus source, the phosphorus solubility of strain JL-1 in different insoluble phosphorus sources was detected by using Mo-blue colorimetric method, particle-size distribution, ultrasonic crushing, HPLC detection were used to study the dissolving effect on calcium phosphate, the storage of phosphorus, and the produced organic acids and phosphatase activity during fermentation. [Results] Acinetobacter indicus JL-1 showed the best phosphate-solubilizing ability in the liquid medium with calcium phosphate, the solubilizing phosphate concentration peaked at 118.04 μg/mL at 48 h incubation. Strain JL-1 had the dissolving effect on calcium phosphate and could absorb a part of the released phosphorus. The dissolved phosphorus was released by the combined action of organic acids and phosphatase. Organic acids contained gluconic acid, propionic acid, acetic acid, lactic acid, etc. and propionic acid content was up to 118.11 mg/mL; the highest acid phosphatase activity was 22 901.32 μmol/(L·h), and the highest alkaline phosphatase activity was 23 826.02 μmol/(L·h). [Conclusion] Strain JL-1 had the erosion effect on calcium phosphate, the soluble phosphate was released by the organic acids and phosphatase produced during fermentation, some of the phosphate was absorbed by strain cells. The results improve the feasibility that Acinetobacter indicus can be used in agricultural production and provides data reference.
