Dynamics of plastisphere microbial communities in mangrove sediments and their potential impact on N-cycling

Plastic pollution has emerged as a significant environmental issue in marine ecosystems. The prolonged presence of plastics in mangrove sediments can have a substantial impact on the carbon and nitrogen cycles of these vital environments. We conducted in situ burial exposure experiments to assess microbial colonization and activity on biodegradable and refractory plastics in mangrove sediments, with a focus on their influence on nitrogen cycling. Variations in microbial community succession and metabolic processes on plastic surfaces were primarily determined by the type of plastic polymer. After 60 days of exposure, the abundance of denitrifying bacteria and denitrification-related genes (narG, nirS, nosZ, and norB) was higher on biodegradable plastics. After 360 days, however, a high abundance of ammonia-oxidizing archaea and nitrification-related genes (pmoA-amoA, pmoB-amoB, pmoC-amoC, and hao) were found on refractory plastics. Consequently, plastic pollution in mangrove sediments could disrupt the nitrogen cycling equilibrium in these ecosystems, underscoring the critical necessity to regulate and alleviate the detrimental impacts of plastic pollution in crucial coastal areas.