Waterway use by humans exposes them to potentially pathogenic microbial communities, posing a threat to public health. Additionally, the varying uses of waterways, such as agricultural, industrial or human recreational creates distinctive chemical properties and available metabolites allowing for formation and propagation of unique microbial communities. However, correlations between chemical environments in waterways and their microbial communities remain indistinct. This study monitored changes in the chemical make-up of three distinct sites throughout the Blue Marsh watershed in an attempt to determine correlations between microbial populations and chemical properties in waterways over time. Testing was performed monthly over a one-year period, including chemical tests for pH, temperature, inorganic phosphates, inorganic nitrates, and dissolved oxygen levels. Biolog Ecoplates were used to measure utilization of biochemicals and provide community-level physiological profiling. Microbial communities were monitored through total heterotrophic, Escherichia coli, and Enterococcus counts. The use of 16S ribosomal sequencing identified key pathogenic species in each community.
Results/Conclusions
Chemical analyses found seasonal variability in all measured parameters between and within each site, with an increase in nitrate and phosphate levels for all sites in late fall and mid-spring. E.coli and Enterococci sample counts were found to be above the EPA recommended Recreational Water Quality Criteria in all three sites, on numerous occasions. Metabolic usage analyses displayed a pattern of ten most utilized metabolites shared amongst the three sites. Notably, identified metabolites included Tween 40 and Tween 80, synthetic emulsifiers often used in personal care products and agricultural practices. These findings suggest nonpoint source pollution (NPS) may be present within the watershed and may influence changes in the microbial communities within each site. Microbial population analyses showed diversity among sites, with the quantity of colony forming units rising in the warmer months and peaking when human traffic is heaviest. Pyrosequencing data supported the observed diversity between each site by showing fluctuations in types of species over time. Overall, these results suggest that common human practices can potentially change a waterway’s chemistry, leading to the preferential selection of pathogenic microbial communities. These human induced changes in pathogenic distribution and abundance thus pose a unique threat to human health.