Form-dependent effects of selenium on antibiotic resistome during vermicomposting: Insights into shaping host...

Selenium-assisted vermicomposting represents a promising method for producing selenium-enriched organic fertilizers. This study provides the first systematic evaluation of the effects of different selenium forms (inorganic, organic, and mixed) on vermicompost conversion efficiency and the spread of antibiotic resistance genes (ARGs) in vermicomposting. Herein, we conducted vermicomposting with three concentrations of each selenium form. It was found that selenium supplementation enhanced vermicomposting conversion efficiency and improved compost maturity, with the high-concentration mixed selenium (MS3) exhibiting the most significant effect. Notably, this treatment also increased the removal of total and high-risk ARGs by 17 % and 16 %, respectively, demonstrating its potential for mitigating ARG risk. Mechanistic analysis revealed that selenium supplementation effectively reduced the abundance and diversity of ARGs, especially those linked to mobile genetic elements (MGEs), also markedly shifted the bacterial community structure, reducing the hosts of prevalent ARGs. Consequently, selenium-supplemented vermicomposting yielded a selenium-enriched organic amendment featuring high selenium bioavailability and significantly reduced ARG abundance, thereby providing a sustainable approach to mitigate antibiotic resistance risks during waste valorization.