Enumeration of Clostridium estertheticum Spores in Samples from Meat Plant Conveyors and Silage Stacks by Conventional and Real- Time PCR Procedures

A real-time PCR procedure for enumeration of spores of Clostridium estertheticum, the organism that causes blown pack spoilage of vacuum packaged chilled raw meats was developed. The relationship between cycle threshold (Ct) values and log numbers of spores in samples from which DNA was extracted was linear in the range 3 to 3x10 5 spores (R 2 >0.99). Samples collected from conveyor belts for primal cuts at a beef packing plant and from silage stacks were processed for enumeration of C. estertheticum spores by cultivation and real-time PCR. The organism was not recovered from any samples using culture method; but PCR results indicated that spores were present in 35 of 63 samples from conveyor belts and 4 of 38 silage samples, at numbers between 3 and 108/sample and 5 and 119/g, respectively.