Recovery and survival of Escherichia coli O157:H7 in reconditioned pork-processing wastewater.
The pathogen Escherichia coli O157:H7 has been recovered from various water sources and food samples. The growth potential of this bacterium in nutrient-limited, reconditioned wastewater from a pork-processing plant was determined over a temperature range of 4 to 46 degrees C. Even though the biological oxygen demand of the wastewater was <2 mg/liter, results of bioassays for assimilable organic carbon and the coliform growth response of the water suggested that sufficient nutrients were present to support limited bacterial growth. A three-strain mixture of E. coli O157:H7 grew over the temperature range of 10.2 to 29.4 degrees C. Bioassays appear to be a good indicator of the ability of this wastewater to support growth of this pathogen. Statistically higher levels of bacterial growth (P < 0.05) were detected on a nonselective medium (tryptic soy agar) than on a selective medium (sorbitol-MacConkey agar), suggesting that stress or injury of the bacterium occurs when the organism is exposed to the nutrient-limited conditions of the wastewater. These results indicate that E. coli O157:H7 can survive and grow in this particular nutrient-limited wastewater, suggesting a potential hazard if this water becomes contaminated with this pathogen.
Rajkowski
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U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, Pennsylvania 19038-8598, USA. krajkowski@arserrc.gov
Rice
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D000822:Animal Husbandry; D000818:Animals; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D013552:Swine; D013696:Temperature; D014865:Waste Disposal, Fluid; D014871:Water Microbiology