Factors Influencing Growth and Survival of E. coli on Salad Vegetables
Faculty Mentor
Phillip Scheuerman
Mentor Home Department
Environmental and Occupational Health and Safety Sciences
Short Abstract
This project aimed to understand the survival of Escherichia coli on salad vegetables. The study analyzed the influence of time and temperature on the growth and survival of E. coli. The incubation temperatures were 4°C, 25°C, and 35°C and the incubation time was 7 days with plating occurring after one, three, and seven days in that span. This study provides information on the safety of unwashed lettuce after being exposed to bacteria for days. The results were expected to support the hypothesis that the growth of E. coli would be directly proportional to the incubation temperature. Nine flasks were used for each experiment: 3 were E. coli inoculated into sterile milli-q water (control for E. coli growth without nutrients), 3 were uninoculated and unwashed lettuce in sterile milli-q water (control to account for natural bacteria present on the lettuce), and three were E. coli inoculated on unwashed lettuce in sterile milli-q water. Incubation occurred at 4°C (refrigerator), 25°C (room temperature), and 35°C (incubator) over several days. The E. coli solution was plated using the micro-drop plating technique, with ten μl drops. The plates were incubated for 24 hours at 37°C and counted afterward. The results suggest that the largest concentration of bacteria and E. coli occurred at the highest incubation temperature, and the lowest concentration at the lowest incubation temperature. This conclusion supports the study hypothesis and suggests human health risks posed by unwashed vegetables stored for multiple days regardless of temperature.
Category
Health
Start Date
5-4-2024 9:10 AM
End Date
5-4-2024 10:10 AM
Location
D.P. Culp Center Room 219
Factors Influencing Growth and Survival of E. coli on Salad Vegetables
D.P. Culp Center Room 219
This project aimed to understand the survival of Escherichia coli on salad vegetables. The study analyzed the influence of time and temperature on the growth and survival of E. coli. The incubation temperatures were 4°C, 25°C, and 35°C and the incubation time was 7 days with plating occurring after one, three, and seven days in that span. This study provides information on the safety of unwashed lettuce after being exposed to bacteria for days. The results were expected to support the hypothesis that the growth of E. coli would be directly proportional to the incubation temperature. Nine flasks were used for each experiment: 3 were E. coli inoculated into sterile milli-q water (control for E. coli growth without nutrients), 3 were uninoculated and unwashed lettuce in sterile milli-q water (control to account for natural bacteria present on the lettuce), and three were E. coli inoculated on unwashed lettuce in sterile milli-q water. Incubation occurred at 4°C (refrigerator), 25°C (room temperature), and 35°C (incubator) over several days. The E. coli solution was plated using the micro-drop plating technique, with ten μl drops. The plates were incubated for 24 hours at 37°C and counted afterward. The results suggest that the largest concentration of bacteria and E. coli occurred at the highest incubation temperature, and the lowest concentration at the lowest incubation temperature. This conclusion supports the study hypothesis and suggests human health risks posed by unwashed vegetables stored for multiple days regardless of temperature.