<ol> <li>Evaluate transport trailers as source of Escherichia coli 0157:H7 and species of Salmonella in stocker cattle arriving at feedlots.
<li>Determine the effect of Lactobacillus acidophilus on the local and systemic immune response in pigs and cattle.
<li>Develop molecularly imprinted polymers (MIPs) to rapidly detect E. coli 0157:H7 in primary enrichment procedures currently used for detection of this pathogen in foods.
<li>Optimize a fluorescence-based PCR assay for non-gel PCR detection of Listeria monocytogenes in foods.
<li>Compare the inhibitory action, toward E. coli 0157:H7 and Salmonella Enteritidis, of oil and aqueous extracts from two varieties (Turkish and Spanish) of field grown oregano.
<li>Develop cultural methods for detection and/or enumeration of Helicobacter pylori in foods and investigate its incidence of occurrence in the food supply.
<li>Determine if abnormal prion proteins can be removed or inactivated from animal byproducts using novel processing approaches such as protein sobulization.</ol>
A. Microbial food safety is of high priority not only for processors and consumers but also for producers of livestock. Escherichia coli 0157:H7 and Listeria monocytogenes are two food borne pathogens currently causing great concern, especially in foods of animal origin. Helicobacter pylori is a relative new inculsion in the list of food borne pathogens. However, methods of detecting it in foods are lacking. B. New or improved methods of detecting and/or controlling these pathogens would greatly enhance our ability to ensure consumers of a safe food supply. A. This project investigates a possible route of transmission of Escherichia coli 0157:H7 among cattle during shipment to feedlots. It also invistigates the potential mechanism whereby feeding probiotics to livestock reduces the incidence of E. coli 0157:H7 and other pathogens in pigs and cattle. It further investigates a novel method for control of these pathogens in refrigerated foods. B. Another focus of the project is to develop or improve methods of detection used to screen or monitor foods for the pathogens.
Samples will be collected from commercial transport trailers in which feeder cattle are delivered to feedlots and assayed for both E. coli 0157:H7 and species of Salmonella. Blood for pigs and cattle being fed a commercial culture of L. acidophilus will be compared to that from control animals to determine if differences occur in the intensity of the immune responses. Biosensors made from molecularly imprinted polymers specific for E. coli 0157:H7 will be prepared and tested for the ability to rapidly detect the pathogen in enrichment cultures used to examine foods. A commercially available fluorescent primer and primers specific of L. monocytogenes will be used to develop a non-gel PCR for this pathogen in foods. Both of these sensors could greatly speed the screening of foods for these pathogens. Helicobacter pylori is being recognized as an important foodborne pathogen. However, cultural methods are lacking that enable us to easily detect the organism in foods. We plan to develop a suitable cultural method to achieve this. Oregano oil has been shown to exert inhibition of a number of microorganisms. Our goal is to compare two varieties of oregano including both the oil and aqueous extract for ability to inhibit foodborne pathogens on refrigerated foods.
No significant difference was observed in phagocytic activity of immune cells isolated from young calves fed a probiotic culture of Lactobacillus acidophilus compared to those from control animals. There also was no effect observed in the pro-inflamatory cytokine gene assay of the calves fed the probiotic compared to the controls. A real-time PCR system was developed and tested for the detection of Listeria monocytogenes in ready to eat meat products.It was compared to the more cumberson and time consuming traditional method used by USDA/FSIS. The PCR method was much faster, permitting detection in a total of two days. It, however, is essential to carefully select target-specific primers in order to avoid false positives. Thus the primer must be validated for specificity. The minimun detectable level of L. monocytogenes in the enrichment culture was 1X10E5 colony forming units per ML.
Results from this study should provide information useful in providing and/or assuring the safety of our food supply throughout the food production and processing chain. Improved more rapid methods of detecting food borne pathogens is important to provide reliable early detection to prevent exposure of consumers. Improved methods of controlling the pathogens also will enable us to provide a safer food supply.