Enhancing Food Safety Through Control of Food-Borne Disease Agents

NON-TECHNICAL SUMMARY: Food-borne pathogens have a significant impact on human health and the food industry in the United States. This project aims to discover new methods to prevent, reduce or eliminate food-borne disease agents at all points of the food chain, from "farm to fork."

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APPROACH: Pathogenic bacteria may enter onto fruits and vegetables through animal manure. Prevention of foodborne illness through this route can be achieved through adequate holding times from manure application to soil and the harvest period. To determine the holding time of manure, foodborne pathogens associated with transmission through livestock (E. coli O157:H7 and Salmonella sp.) will be engineered to produce green fluorescent protein (GFP) to allow non-selective enumeration through the holding time of the manure amended soil. The soil will be amended with inoculated manure and sampled over a course of time to determine the die-off of the different pathogens. From this information, it will be possible to determine the holding time necessary before harvesting produce to ensure sufficient reduction in pathogenic bacteria levels to enhance the safety of fruits and vegetables. These GFP engineered pathogens will also be used to screen the inoculated pathogens from other microorganisms present to track the effectiveness of therapeutic regimes in animals. Since the gastrointestinal tract of animals contains a high number of different bacteria, it is necessary to have a non-selective identification of the inoculated pathogens to assess the efficacy of the various treatments. In an attempt to prevent the colonization of pathogens in animals, natural barriers such as non-pathogenic bacterial strains capable of colonizing the gastrointestinal tract of animals will be investigated. The GFP pathogenic strains will be used to enumerate and assess the efficacy of the various natural barriers in their ability to prevent or rid the colonization of pathogens in the intestinal tract of animals. The transfer of antibiotic resistance genes to pathogens by other microorganisms is believed to occur in the intestinal tract of various animals. The large numbers, close proximity, addition of selective pressure and diversity of microorganisms is believed to contribute in the ability of the pathogens to acquire antibiotic resistance genes from various bacteria. To determine whether pathogens are able to acquire the antibiotic resistance genes from other bacteria, the GFP pathogens will be used to follow the antibiotic resistance acquisition, if any, through the exposure of the various microorganisms.

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PROGRESS: 2000/10 TO 2006/09<BR>
Alternative methods to enhance the safety of sprouts and fruit juices have been developed. Ultraviolet light treatment system for juices was developed and proven to achieve a 5-log reduction against the pertinent pathogens Escherichia coli O157:H7 and Cryptosporidium parvum. UV is a non-thermal processing method that was shown not to change the flavor of apple cider compared to thermal treatment of cider. The effectiveness of UV was determined not to be influenced by varying levels of acidity. Different blends of apple cider and different fruit and vegetable juices were used to determine the UV exposure required to achieve the minimum 5-log reduction. The cost of operation for the UV treatment was 0.12 dollars for one hour of operation which equaled the treatment of up to 420 gallons of cider. This effective and economical alternative has resulted in more than 250 commercial UV units in use across the US. In an attempt to enhance the safety of sprouts, mild heat treatments of 55 celcius for 4 to 8 days was shown to be effective in achieving a greater than 5-log reduction in E. coli O157:H7 and Salmonella spp. on alfalfa and mung bean seeds. The germination rates for the seeds after 4 to 8 days of heat treatment were not significantly affected. The treatment could be used on seeds prior to selling at the seed supplier or alternatively by the sprout producer.
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IMPACT: 2000/10 TO 2006/09<BR>
Effective and inexpensive treatment methods were developed for small juice manufacturers and sprout producers. These findings will allow for small juice and sprout producers to guarantee the safety of their products and protect their consumers while at the same time, allow them to remain in business due to the low cost of equipment and operation.