Revealing the Response of Microbial Communities to Polyethylenemicro(Nano)Plastics Exposure in Cold Seep Sediment

To date, multiple studies have shown that the accumulation of microplastics (MPs)/nanoplastics (NPs) in the environment may lead to a series of problems. However, the effects of MPs/NPs on the microbial communities and biogeochemical processes, particularly methane metabolism in cold seep sediments, have not been well elucidated. In this study, an indoor microcosm experiment for a period of 120 days exposure of MPs/NPs was conducted. The results showed that MPs/NPs addition did not significantly influence bacterial and archaeal richness in comparison with the control (p > 0.05), whereas higher levels of NPs (1%, w/w) had a significantly adverse effect on bacterial diversity (p < 0.05). Moreover, the bacterial community was more sensitive to the addition of MPs/NPs than the archaea, and Epsilonbacteraeota replaced Proteobacteria as the dominant phylum in the MPs/NPs treatments (except 0.2% NPs). With respect to the co-occurrence relationships, network analysis showed that the presence of NPs, in comparison with MPs, reduced microbial network complexity. Finally, the presence of MPs/NPs decreased the abundance of mcrA , while promoting the abundance of pmoA . This study will help elucidate the responses of the microbial communities to MPs/NPs and evaluate their effects on methane metabolism in cold seep ecosystems.