Differential Characteristics of Waterborne Bacterial Pathogens and Virulence Factors between Suspended Particulate Matters and Aqueous Phase in the Pearl River and Pearl River Estuary

Compositional characteristics and environmental behaviors of waterborne pathogenic bacteria need to be addressed for understanding their potential health risks. Herein, water samples collected from the Pearl River (PR) and Pearl River Estuary (PRE) were analyzed using metagenomic approaches. Seventy-one putative pathogenic bacterial species identified in the PR and PRE water belonged to 6 phyla, with Bacteroidetes being predominant. The total level of pathogenic bacteria ranged from 1.59 × 107 to 1.46 × 108 cells/L, with a declining trend from the PR to the PRE. Pathogenic particle-attached bacteria (PAB) accounted for approximately 81.4% and 71.8% of the total pathogenic bacteria in bottom and surface water, respectively. A significant correlation between pathogenic PAB and free-living bacteria (FLB) was observed in the PR and PRE water (p < 0.01), indicating a dynamic distribution between the suspended particulate matters (SPMs) and aqueous phase. Various functional genes encoding virulence factors (VFs) were detected in the PR and PRE water, where the most popular and abundant VFs were related to bacterial adherence. This study implied that SPMs could play pivotal roles in the transport of pathogenic bacteria in the aquatic environments and PAB might make a primary contribution to the potential health risks.