Enhanced biodegradation of crude oil by phosphate-solubilizing bacteria Bacillus subtilis PSB-1: Overcoming soluble phosphorus deficiency

Abstract

Due to the oligotrophic marine environment, the lack of phosphorus is one of the key factors limiting the oil biodegradation ability of microorganisms after the oil spill occurs. Overcoming phosphorus deficiency has become an urgent problem. In this study, a phosphate-solubilizing bacteria, named Bacillus subtilis PSB-1, with the crude oil degradation efficiency up to 93.7 %, was isolated from oil contaminated seawater. The strain PSB-1 significantly increased the content of solubilized phosphorus (P) to promote the degradation of oil pollutants. The yielding bioavailable P from 5 g·L⁻¹ Ca₃(PO₄)₂ and 2 g·L⁻¹ sodium phytate was up to 17.14 mg·L⁻¹ and 35.63 mg·L⁻¹ in the culture with crude oil as the sole carbon source. The production of organic acids, such as oxalic and lactic acids, peaked at 263.52 mg·L⁻¹ and 282.99 mg·L⁻¹, respectively, indicating a potential enhancement of P availability due to the crucial role of organic acids in the process of P solubilization. The analysis of the degradation pathway of hydrocarbons and the content of alkaline phosphatase (AKP) under organic P deficiency indicated that pyruvate served as an intermediate product connecting P solubilization and hydrocarbons degradation. Molecular docking analysis provided evidence that AKP can interact with hydrocarbon molecules, suggesting a role in the degradation of hydrocarbons. This study offered a new way to oil spill bioremediation with the P deficient environment.