Co-occurrence of toxic metals, bacterial communities and metal resistance genes in coastal sediments from Bohai bay

• Published in: Environmental pollution (1987) Vol. 338; p. 122666
• Main Authors: Guo, Yiyan, Wu, Chao, Wang, Zhi, Shi, Yifeng, Sun, Jun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2023
• Subjects: autumn; bacterial communities; Bacterial community; Bohai bay; coastal sediments; community structure; ecological restoration; genes; heavy metals; High-throughput sequencing; Metal resistance genes; metal tolerance; pollution; Proteobacteria; quantitative polymerase chain reaction; risk; Sediment; summer; toxicity; Yellow Sea; Yellow Sea; Bohai bay; Sediment; Metal resistance genes; High-throughput sequencing; Bacterial community
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2023.122666

Sediment heavy metal contamination poses substantial risks to microbial community composition and functional gene distribution. Bohai Bay (BHB), the second-largest bay in the Bohai Sea, is subject to severe anthropogenic pollution. However, to date, there have been no studies conducted to evaluate the distribution of metal resistance genes (MRGs) and bacterial communities in the coastal sediments of BHB. In this study, we employed high-throughput sequencing based on 16S rRNA genes and real-time quantitative PCR (qPCR) to provide a comprehensive view of toxic metals, MRGs, and bacterial communities in BHB's coastal sediment samples across two seasons. We detected high levels of Cd in the summer samples and As in the autumn samples. The metal content in most autumn samples and all summer samples, based on ecological indices, indicated low ecological risk. Proteobacteria dominated all samples, followed by Desulfobacterota, Bacteroidota and Campilobacterota. Bacterial community variability was higher between autumn sampling sites but more stable in summer. We detected 9 MRG subtypes in all samples, with abundances ranging from 4.58 × 10−1 to 2.25 copies/16S rRNA copies. arsB exhibited the highest relative abundance, followed by acr3, czcA and arrA. The efflux mechanism is a common mechanism for sediment resistance to metal stress in Bohai Bay. Procrustes analysis indicated that bacterial community composition may be a determinant of MRGs composition in BHB sediments. Network analysis suggested that eight classes could be potential hosts for six MRGs. However, this type of correlation requires further validation. To summarize, our study offers preliminary insights into bacterial community and MRG distribution patterns in heavy metal-exposed sediments, laying the groundwork for understanding microbial community adaptations in multi-metal polluted environments and supporting ecological restoration efforts. [Display omitted] •1.The distribution of heavy metals and MRGs shows clear spatial and temporal patterns.•2.Cu concentrations and corresponding resistance gene copA abundance are relevant.•3.Efflux mechanism is common for sediment resistance to heavy metal stress in Bohai Bay.•4.High heavy metal contamination reduced bacterial diversity.•5.Bacterial community was the primary factor affecting MRGs.