Biodegradation of petroleum by anaerobic microbial communities enriched from mangrove sediments

Mangrove sediments are increasingly threatened by petroleum contamination. However, its anaerobic degradation by microbial communities remain poorly understood. In this study, the anaerobic microbial communities were enriched by supplementing petroleum as the sole carbon source and sulfate and nitrate as dual electron acceptors from sediments of three mangrove wetlands. The enriched bacterial community acquired a high degradation capacity, with degradation rates ranging from 65.20% to 93.20% for petroleum, and 64.68% to 99.92% for alkanes in petroleum. Bacterial genera Pseudomonas, Bacillus, Shewanella and Desulfocurvibacter, etc. were the dominant taxa during petroleum degradation. Microbial communities such as Shewanella harbor genes involved in petroleum degradation, including hydrocarbon degradation genes assA/masD, and the aromatic hydrocarbon degradation genes bssA/nmsA. Through the fumarate addition pathway, they degrade hydrocarbons to produce metabolites utilized by SRB and nitrate-reducing bacteria, thereby driving electron transfer and nitrogen/sulfur cycles. Methane production is achieved via the methanogenic archaeon Methanofollis, forming a petroleum hydrocarbon degradation metabolic network. This study provides novel insights into the biodegradation of petroleum by the anaerobic microbial communities enriched from mangrove sediments.