Lactic acid bacteria as bioremediation agents for chlorpyrifos degradation: a combined chemical and in silico approach

Aim: Organophosphorus pesticides (OPPs) have massively polluted ecosystems worldwide. Bioremediation by lactic acid bacteria (LAB) has been demonstrated to be an effective method to degrade them. This study aimed to evaluate the degradation capacity of four LAB strains on OPPs, using chlorpyrifos (CF) as the target pesticide. In addition, the interaction mechanism between CF and phosphatase enzyme was approached. Methods: The degradation of CF by LAB strains was assessed over 24 h, and the remaining CF, along with its degradation products, were detected by gas chromatography-mass spectrometry (GC-MS). Molecular docking analysis was performed to determine the binding affinity between CF and phosphatase and to visualize the interaction within the binding pocket. Results: The biodegradation of CF by L. mesenteroides, L. paramesenteroides, P. pentosaceus, and L. fermentum followed first-order kinetics, with degradation rate constants of 0.1318, 0.0279, 0.0241, and 0.0178 h–1, respectively. In accordance with the higher k value, L. mesenteroides isolated from vegetables exhibited the highest CF degradation rate (97%). Supporting this observation, CF showed significant binding affinity toward phosphatase from L. mesenteroides, with free energy values ranging from –5.79 to –5.77 kcal mol–1. Conclusions: A positive correlation (P < 0.05) was observed between L. mesenteroides degradation behavior, phosphatase activity, and the degradation rate constant, indicating a metabolism better adapted to OPP stress conditions. The active site of the phosphatase, containing the Gly127-Glu128-Ser129-Ser130-Gly131 motif, was identified in pocket 1, suggesting that catalysis likely occurs at this site.