The objective of this project is to identify the production of volatile compound(s) (VOCs) that are unique to specific foodborne pathogenic bacteria and differentiates these from common spoilage bacteria. To develop non-invasive detection strategies that would integrate the bacteria specific volatiles with biosensor type systems and to design the testing methodologies for their use.
A great deal of research has been conducted recently on the development and design of biosensor systems. A major obstacle for their use and other conventional microbial detection systems is sensitivity and attainment of a totally representative food sample for analysis. The later is due to the random distribution of pathogens in food. Presently we have been able to identified VOCs specific for E. coli O157:H7, L. monocytogenes, S. typhimurium and S. aureus as compared to common spoilage food bacteria Pseudomonas and Moraxella when grown on Trypticase Yeast Soy Extract slants and detected by Solid Phase Micro Extraction and GC-MS. The experimental design has been improved and was successful in demonstrating the reproducibility of confirmation test. E. coli O157:H7 and S. typhimurium were grown on selected agar medium to model protein, carbohydrate and fat based foods. VOC production was compared to common spoilage bacteria (Pseudomonas and Morexella. E. coli and S. typhimurium produced specific VOCs not found in either selected agar media blanks or spoilage organism samples. We have added Cyranose 320 portable electronic nose testing to our protocol in FY01 and initiated trial studies for volatile pattern recognition with selected agar medium.