Work

Unveiling biodegradation mechanism of phoxim: Novel metabolic pathway, functional gene, detoxification effect, and widespread distribution of phoA

Year: 2025

Type: article

Abstract: Phoxim, an organophosphorus insecticide (OP), poses risks to non-target organisms in the environment. However, the biodegradation mechanism of phoxim was not fully understood. In this study, a novel detoxification pathway for phoxim in Delftia lacustris PX-1 was identified. A gene cluster pho ( phoABC1C2DEFGHI ), located on the plasmid, was found to be involved in phoxim degradation. The genes phoA , phoB , and phoD , which were responsible for converting phoxim to benzoate, were functionally characterized in vitro . Notably, PhoA was highly abundant in global cultivated lands. Moreover, acute toxicity experiments showed that both phoxim and its metabolite, 2-hydroxyimino-2-phenylacetonitrile (2H2P), exhibited moderate toxicity to zebrafish, whereas strain PX-1 could detoxify both compounds through degradation. After exposure to 2 mg L −1 phoxim, the brain acetylcholinesterase (AChE) activity levels of zebrafish dramatically decreased by 31.28 % ( P < 0.05) relative to unexposed controls. Interestingly, phoxim could promote the colonization of strain PX-1 in the zebrafish gut, which mitigated phoxim-induced damage to AChE activity in the zebrafish brain. In summary, our research reveals a novel phoxim detoxification mechanism and provides a theoretical foundation for the bioremediation of residual phoxim in the environment In brief This study reveals a novel metabolic pathway for phoxim biodegradation and elucidates the detoxification mechanism of strain PX-1 in zebrafish.

Source: Environment International

DOI: 10.1016/j.envint.2025.109809