Enhancing Benzo[a]pyrene Degradation by Pantoea dispersa MSC14 through Biostimulation with Sodium Gluconate: Insights into Mechanisms and Molecular Regulation

We investigated biostimulation as an effective strategy for enhancing the degradation efficiency of recalcitrant organic compounds, with MSC14 (a novel polycyclic aromatic hydrocarbon degrading bacterium Pantoea dispersa MSC14) as the study material. Here, we investigated the impact of sodium gluconate on MSC14-mediated degradation of B[a]p. This study focused on the application of sodium gluconate, a biostimulant, on MSC14, targeting Benzo[a]pyrene (B[a]p) as the model pollutant. In this study, the novel PAHs-degrading bacterium P. dispersa MSC14 demonstrated the capability to degrade 24.41% of B[a]p after 4 days. The addition of the selected sodium gluconate stimulant at a concentration of 4 g/L stimulated MSC14 to degrade 54.85% of B[a]p after 16 h. Intermediate metabolites were analyzed using gas chromatography-mass spectrometry to infer the degradation pathway. The findings indicated that sodium gluconate promoted the intracellular transport of B[a]p by MSC14, along with the secretion of biosurfactants, enhancing emulsification and solubilization capabilities for improved B[a]p dissolution and degradation. Further analysis through transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed the formation of a biofilm by MSC14 and an increase in flagella as a response to B[a]p stress. Transcriptome profiling elucidated the interplay of quorum sensing systems, chemotaxis systems, and flagellar systems in the degradation mechanism. Additionally, the study uncovered the molecular basis of B[a]p transport, degradation pathways, metabolic changes, and genetic regulation. In summary, the addition of sodium gluconate promotes the degradation of B[a]p by P. dispersa MSC14, offering the advantages of being rapid, efficient, and cost-effective. This research provides an economically viable approach for the remediation of petroleum hydrocarbon pollution, with broad potential applications.