Characterization of Bacterial Populations in Urban and Rural Houston Watershed Soil Samples Following a Flooding Event

Abstract

Since Houston is prone to flooding events, bacterial population dynamics in Houston watershed soils pre- and post-Hurricane Harvey were evaluated. Unexpectedly, bayous closer to Houston’s urban core, including Buffalo, Halls, Mustang, and Horsepen Bayous, had significantly higher enteric bacterial loads during the winter than the summer, likely due to water flow rate changes or proximity to wastewater outflow. Following bacterial load determination, isolated colonies were identified using biochemical tests. Additionally, metagenomic sequencing of 16S rDNA allowed for identification of both culturable and unculturable organisms. The phyla Proteobacteria, Actinobacteria, Bacteriodetes and Firmicutes were found to be dominant in our metagenomic analysis and are human gut bacteria. Some opportunistic bacterial Proteobacteria pathogens identified in our metabolomic analysis were Serratia marcenscens, Pseudomonas mendocina, Pseudomonas fulva, and Pseudomonas putida. To our knowledge, this is the first study that compares Houston-area bacterial populations before and after a major flooding event. Taken together, Hurricane Harvey likely contributed to a redistribution of enteric bacteria, as there was a significant increase in the enteric population of Buffalo and Halls Bayous. Similarly, our 2018 winter data set followed the same trend, as significant increases were seen in the enteric populations of Horsepen, Mustang, and Cypress Creek watershed soils.