Improving food safety with natural organisms that can outcompete diseases

Problem Title

Improving food safety with natural organisms that can outcompete diseases

Scientific Title

Competitive exclusion as a method for eliminating foodborne pathogens

Student: 
Emily Travers
Major(s): 
Food Science
iCons Concentration: 
Renewable Energy
iCons Class Year: 
Class of 2014
Executive Summary 

Foods that are consumed uncooked and are not extensively processed pose a threat to food safety. Even fruits and vegetables have a high risk of carrying foodborne pathogens. Competitive exclusion is a method that could potentially eliminate much of the health risk associated with consuming raw foods. Sprouts are grown in water under warm, moist, conditions that make them a hot bed for pathogenic growth. This goal of this study has been to look at the facets of the growth stages of sprouts and to determine if any naturally occurring competitive exclusion is present and if found, to isolate the organisms that inhibit harmful pathogens.

To do this stock supply and waste water were obtained from a local sprout farm. Both samples were diluted down to generate appropriate levels of growth. The samples were plated onto TSA agar and incubated at 32°C for 24 hours. Once sufficient growth had occurred the plates were retrieved, the agar removed from the plate and flipped over. A sample pathogen (either E.coli or Salmonella) was then streaked on the other side of the agar. The plates were incubated at 37°C for a 24 hour period and observed to determine if any clearing had occurred. Additionally multiple varieties of sprouts were obtained (bean, alfalfa). 25g of dried sprouts were selected for testing and 225 ml of water added, the mixture was then stomached, diluted, and plated in the same manner as was done when only the water samples were being used. The same pathogens were used to search for clearing that would indicate competitive exclusion organisms. The incubation time and following observations remained the same.

No resulting clearing has occurred thus far in the proceedings. From this it can be concluded that no competitive exclusion organisms have been present in the samples used.

Problem Keywords: 
E. Coli
food safety
Salmonella
Scientific Keywords: 
competitive exclusion