Metagenomes in Methane-Rich Deep Coastal Sediments

Coastal sediments are rich in embedded recalcitrant organic carbons that are biotransformed into methane. In this study, bacterial 16S rRNA community composition, gas composition (carbon dioxide, methane, nitrogen), and chemical indicators (total nitrogen, total carbon, and total sulfate) were examined in five deep sediment cores (over 130 m in length) obtained from the Hangzhou Bay. The V3-V4 region of the 16S rRNA gene amplicons was amplified and sequenced for the community analysis. We conducted a metagenomic sequencing of the two sediment samples, with a high methane content and enrichment of methanogenic Bathyarchaeota. A total of 27 draft genomes were retrieved through metagenomic binning methodologies and were classified into Bathyarchaeota, Asgard archaea, Planctomycetes, and other microbial groups. The species composition, along with the physicochemical factors of the core sediments, revealed a strong correlation with methane content, particularly in sample S-2.