Spatial and temporal changes of microbial community structure and antibiotic resistance genes in the coastal waters of Haizhou Bay

Abstract:

[Background] The pollution and accumulation of antibiotic resistance genes (ARGs) in coastal waters directly affect the quality and safety of seafood. As one of the four major fishing grounds, Haizhou Bay is the main carrier of fishery development in Jiangsu province, with multiple rivers injected. The coast is an important agricultural area with a significant impact on public health. [Objective] To study the microorganisms and ARGs in the water and sediment samples collected from six points of Haizhou Bay in summer and autumn. [Methods] Metagenomic sequencing was employed to determine the composition and relative abundance of microorganisms and ARGs. [Results] Proteobacteria and Actinobacteria were the most dominant phyla in the two media in summer and autumn. The dominant families in water and sediment samples were Rhodobacteraceae and Desulfobacteraceae, respectively. The relative abundance of ARGs in water samples in summer was significantly higher than that in autumn, while the relative abundance of ARGs in sediments did not show a significant trend in different seasons. The resistance mechanisms of the main phyla in water samples were mainly antibiotic target replacement and antibiotic target protection, while that in the sediment samples was mainly antibiotic inactivation. The main families had more diverse resistance mechanisms. Redundancy analysis (RDA) and canonical correspondence analysis (CCA) showed that environmental factors such as nitrate and salinity were significantly correlated with the changes of ARGs.[Conclusion] The microbial community and ARGs in the coastal area of Haizhou Bay varied in different media in summer and autumn, and the main microbial communities in different media adopt different resistance mechanisms. The relative abundance and distribution of ARGs were regulated by environmental factors such as salinity and nitrate. The findings provide a theoretical basis for public safety monitoring and environment protection in Haizhou Bay.