Microbial biodegradation of polyethylene terephthalate microplastics by an indigenous Candida tropicalis strain and biocompatibility evaluation of microplastics-degraded metabolites in GIFT Tilapia

Microplastic pollution is known to impact various abiotic and biotic components of ecosystems. Among the various microplastic remediation methods, biological approaches using microbes have gained significant attention due to their high efficacy and eco-friendly nature. In this study, the degradation of PET-based microplastics was carried out by the indigenous yeast strain in in vitro batch degradation experiments. The degradation was measured by monitoring the optical density of the yeast grown on a medium containing microplastic pieces, as well as assessing weight reduction and biofilm formation efficiency (%). After degradation, the metabolites were extracted and tested for their toxic effects on the growth parameters of the freshwater fish . Extracted metabolites were administered to at different concentrations, and the effects on growth parameters-such as daily weight gain (%), weight gain (%), specific growth rate (%), and survival (%), along with histological examinations of gut and gill tissues-were evaluated. In silico docking studies were also performed to assess the potential toxic effects of the major constituents of the metabolites (polyethylene terephthalate, 3-butynoic acid, butanoic acid, cyclopentene-3-ethyl, ethanedioic acid, and formic acid) on the target fish protein (PDB ID: 6Y7I). The administered metabolites did not show any impact on the growth parameters. Histopathological examination also revealed no alterations or abnormalities in the gut and gill tissues. Furthermore, in silico docking studies indicated no toxic effects on the freshwater fish . These findings clearly demonstrate the effectiveness of in degrading microplastics from various environmental sources, with high efficacy and biocompatibility.