Grantee Research Project Results

Re-Growth of Pathogens in Cow Fecal Extract

EPA Grant Number: F13E30937
Title: Re-Growth of Pathogens in Cow Fecal Extract
Investigators: Oladeinde, Adelumola Adeoye
Institution: University of Georgia
EPA Project Officer: Packard, Benjamin H
Project Period: August 1, 2014 through August 1, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Environmental

Objective:

Cow fecal extract is rich in dissolved organic matter (DOM) and dissolved organic nitrogen (DON), which can be used as a nutrient source. In addition, the photodegradation of DOM results in the release of a variety of photoproducts that can stimulate the growth and activity of microorganisms in aquatic environments. This research uses cow fecal extract to understand the potential factors responsible for the re-growth of shiga-toxin producing E. coli 0157:H7, E. coli 026:H11 and fecal indicator bacteria (FIB). In addition, this research will explore the potential positive effects ultraviolent (UV) irradiation can play in aiding their re-growth in cow fecal extract.

Approach:

To achieve this objective, cow manure samples will be made into slurries and diluted to concentrations representing both eutrophic and oligotrophic conditions and then filtered to eliminate all bacteria using 0.2-ìm filters. For each condition, manure extracts will be irradiated using a solar simulator for 6–12 hours prior to inoculation with approximately 102 cells of each pathogen and incubated at room temperature. Samples will be taking for analysis every 6 hours for 72 hours. A growth rate will be determined and samples will be analyzed at each sampling point for the uptake of nutrients, including nitrates, phosphates, ammonium and dissolved organic carbon. In addition, RNA sequencing will be used to investigate gene expression for each pathogen under all conditions tested.

Expected Results:

Sunlight has been shown to aid in the breakdown of dissolved organic matter into more labile compounds that can be easily used by micro organisms for growth. Based on this premise, it is reasonable to hypothesize that UV irradiation will result in a higher growth rate for pathogens inoculated into UV-irradiated manure extract than those inoculated into nonirradiated extracts. In addition, the rate of growth will be pathogen, UV dose and nutrient dependent. Furthermore, pathogens in irradiated extracts are expected to induce an entirely different set of transcription factors than nonirradiated extracts throughout different stages of growth.

Potential to Further Environmental/Human Health Protection

As the world’s population continues to increase, so will the pressure to produce more food. This will result in an increase in the use of manure to facilitate crop yield, as well as an increased need for pasturelands for cattle grazing. Thus a potential threat to surface waters from runoffproducing rain events and direct fecal deposition is foreseeable. Understanding the fate of these pathogens in the environment after shedding through feces will be critical in developing control and adaptation strategies to minimize their transfer.

Supplemental Keywords:

cow fecal extract, E. coli, fecal indicator bacteria

Progress and Final Reports:

2015

Final