Chlorpyrifos degradation by Zhihengliuella sp. ISTPL4: An esterase-driven actinobacterial platform for organophosphorus bioremediation

Abstract

Organophosphorus pesticides (OPs) are widely used agrochemicals that pose serious risks to the environmental and human health due to their persistence and toxicity. This study reports, for the first time, chlorpyrifos (CPF) degradation by actinobacterium Zhihengliuella sp. ISTPL4. Strain ISTPL4 utilized various OPs, including dimethoate, monocrotophos, CPF, and malathion, with the highest growth observed in the presence of CPF as the sole carbon and energy source. Optimal growth and degradation occurred at 28 °C, pH 5, and 3% inoculum in minimal salt medium (MSM). Under optimized conditions, strain ISTPL4 degraded 76.95% of 600 mg L-1 CPF within 7 days. GC-MS analysis identified benzene, 1,3-bis(1,1-dimethylethyl) and phenol, 2,4-bis(1,1-dimethylethyl) as intermediates without the formation of toxic metabolite 3,5,6-trichloro-2-pyridinol (TCP). Whole genome analysis revealed five putative esterase genes potentially associated with CPF degradation. Molecular docking identified carboxylesterase B as the most favorable CPF-binding enzyme, while molecular dynamics simulations supported the stability of the enzyme-substrate complex. A putative metabolic pathway for CPF degradation by strain ISTPL4 was proposed. These findings highlight the potential of Zhihengliuella sp. ISTPL4 as a promising candidate for sustainable bioremediation of OP-contaminated environments.