Molecular approaches improve product safety and quality, speed microbe detection.

Rapid, specific detection of pathogenic and spoilage microorganisms is critical for making a product safe and optimizing its quality. Conventional microbial detection techniques, which range from plate counting to biochemical characterization, are time-consuming and not really suitable for testing some foods, particularly those with a limited shelf life.

Some rapid detection systems may address these concerns, but the presence of microbial contaminants at low levels in products, and interference with the analysis by other components in the product, are major challenges to attempts at rapidly detecting pathogens.

The goal of scientists at The Ohio State University was to establish a commodity-based platform--CleanPlant--suitable for rapidly detecting multiple microorganisms in foods. The researchers determined that the Taqman-based real-time PCR approach was suitable for detecting target spoilage and pathogenic microorganisms in juice and selected processed meat products.

The researchers targeted both the functional genes and rDNA sequences for PCR primer-and-probe development. Their methodology included cloning the target genes from representative strains, determining the DNA sequences, DNA sequence data mining and comparison, and designing primers and probes based on conserved regions within the aligned sequences.

The derived primer-and-probe sets were further tested for detection specificity and sensitivity. Using this strategy, the scientists developed several PCR primer-and-probe sets for detecting pathogenic and spoilage bacteria and fungi. Combined with optimized sample processing procedures, the system they developed detected target agents in juices and roast beef specifically without encountering cross-reaction from other foodborne microorganisms.

The detection procedures can be completed within a working day. This is a significant improvement compared to mainstream industry practices that require from two days to several weeks for cultivating and characterizing these organisms. Efforts are being made to expand the product coverage for the CleanPlant detection system. The system is patent-pending and available for commercialization.

Further information. Hua Wang, Department of Food Science and Technology, Parker Food Science and Technology Building, The Ohio State University, 2105 Fyffe Rd., Room 219, Columbus, OH 43210; phone: [phone]; fax: [phone]; email: [e-mail].