Discipline: Ecology Environmental and Earth Sciences
Shari Galvin - Texas Southern University
Houston, also known as the ‘Bayou City,’ contains 2500 miles of waterways. In August of 2017, Hurricane Harvey released an unprecedented amount of water over Houston and surrounding communities, causing extreme flooding of area bayous. The flooding of waste water treatment plants posed a health risk to the public. Gut bacteria, such as E. coli, can be used as an indicator to measure the safety of water for recreational, industrial, and agricultural purposes. Although indicator bacteria may not directly cause illnesses, they are indicators of potentially harmful pathogens in waterbodies. The greater Houston area bayous that were chosen for this study were Greens, Buffalo, Halls, White Oak and Hunting. To assess the impact of this major flooding event on bacterial populations, we conducted a comparative study between water samples collected during the summer (pre-Harvey) and fall (post-Harvey) months of 2017. Water samples, collected from 15 sites, were tested for the presence of bacteria by quantifying total and enteric bacterial counts. Total bacterial loads were determined using broad medium (i.e., Nutrient Agar) and plate counting. To analyze enteric bacteria, selective and differential medium (i.e. MacConkey) was used along with plate counting. The indicator bacteria, E. coli, was isolated from water samples by membrane filtration according to the methodology outlined in USEPA Method 1603. Additionally, meta-genomic analysis of representative bayou water samples was conducted to comprehensively evaluate bacterial population distributions pre- and post-Harvey. Our results indicate that Hunting, Buffalo and Halls bayou had significantly higher bacterial loads in the summer (pre-Harvey) when compared to the fall (post-Harvey). However, the overall total bacterial loads of Greens bayou were significantly higher in the fall samples when compared to the summer. Except for Buffalo Bayou, temporal analysis of water quality revealed a noticeable increase in the presence of E. coli in post-Harvey samples when compared to pre-Harvey samples. Pathogenic bacteria such as Clostridium spp, environmental Chlamydiae, and Legionella spp where present in higher numbers in the representative pre-Harvey samples when compared to post-Harvey. Conversely, Pseudomonas spp., was present in the environment at 3-fold higher levels in the fall when compared to the summer. This genus contains species that can survive for months in water with minimal nutrients which could account for the higher number in the fall. Future research will involve the evaluation of a representative environmental isolate and lab surrogate following exposure to metal contaminants found in the bayous to determine if isolates are better evolved to handle toxicity found within the environment.
Funder Acknowledgement(s): This research was primarily supported by the National Science Foundation (NSF) through Texas Southern University (TSU) under the award numbers HRD ? 1622993, BCS-1831205, HRD-1829184 and funding source National Science Foundation RISE (HRD-1345173).
Faculty Advisor: Jason A. Rosenzweig, email@example.com
Role: I completed all parts of this research