Assessing the impact of flooding on bacterial community structure and occurrence of potentially pathogenic bacteria in Texas Rivers after Hurricane Harvey

Hurricanes and extreme stormwater events can transport fecal contaminants and a wide range of bacterial pathogens to receiving rivers and streams, threatening public health. This study investigated the impact of flooding on bacterial diversity and the occurrence of fecal and potential bacterial pathogens in Texas Rivers over a short (3 weeks and 3 months) and long time (12 months) after Hurricane Harvey. Water samples were collected from 8 sampling sites of Guadalupe and San Antonio Rivers during three sampling events and bacterial community structure was evaluated using next-generation sequencing (NGS). Results showed that Proteobacteria, Actinobacteria, Bacteroidetes, and Cyanobacteria were the predominant phyla in the water samples. Hierarchal cluster analysis and principal coordinate analysis indicated that bacterial community structure was significantly different in the water samples collected from flooded and non-flooded sites. At genus level, eight fecal-associated and twelve potentially pathogenic bacterial genera were detected in water samples, mainly from flooded sites collected during short-term sampling events. Overall, results suggest that NGS-based microbial water quality monitoring of environmental samples after flooding events could provide critical information about the wide range of pathogens, which can be further assessed by specific methods to identify the risk of exposure.