Microplastics modify the microbial-mediated carbon metabolism in mangroves

Mangroves, a major ecosystem for carbon sequestration, have been recently identified as a microplastic sink, yet the impact of microplastics on the mangrove microbial community is poorly known. Here, we investigated the metabolic activities of mangrove rhizosphere microbiome in the presence of polyethylene, polystyrene, polyamide, and polyvinylchloride, in microcosms, using Biolog™ Ecoplates. Results show that microbial communities in mangrove sediment hold their functional diversity and comprehensive metabolic activity within 56 days of microplastic exposure. However, polyamide and polyvinylchloride microplastics induced a 59.6–66.7% reduction in the rhizosphere microbes’ utilization for their preferred polymer carbon sources. Microbes exposed to polyethylene microplastics showed an activated biotransformation for nitrogen-contained carbon sources. Polyethylene and polyamide microplastics caused a 20.1–22.4% loss available nitrogen. Overall, microplastics are altering the carbon and nitrogen metabolism activities of microbiomes in mangrove wetlands.