Distinct bacterial community structure, assembly and functions between aged and multiple petroleum-contaminated sites

Abstract

Petroleum contamination threatens soil ecosystems, but microbial responses in multi-contaminated area (MCA) and aged-contaminated area (ACA) remain unclear. This study compared bacterial communities in MCA and ACA at China's Lanzhou Petrochemical Site using 16S rRNA sequencing, network analysis and PICRUSt2. MCA had 12-fold higher total petroleum hydrocarbons than ACA, and MAHs and PAHs in MCA were 201-fold and 10-fold higher. PAHs drove bacterial communities in MCA, while those in ACA were shaped by ecological toxicity assessed by whole-cell bioreporter. The network structure of MCA was complex (more modules, positive edges and keystone taxa), whereas that of ACA was relatively simplified. Bacterial community assembly in MCA involved both stochastic (83.09 %) and deterministic (16.91 %) processes, whereas there was only stochastic process in ACA. Bacteria in MCA exhibited stronger carbohydrate metabolic capabilities related to fresh hydrocarbon utilization, whereas those in ACA were more inclined toward amino acid metabolism and membrane transport functions. Our study provides a thorough exploration of soil bacterial response and assembly mechanisms under various petroleum pollution scenarios, offering guidance for developing customized bioremediation strategies in oil-contaminated environments.