Study of the Lactobacillus sakei protective effect towards spoilage bacteria in vacuum packed cooked ham analyzed by PCR-DGGE.

The effectiveness of Lactobacillus sakei B-2 inoculated as a protective culture on the inhibition of spoilage bacteria on sliced vacuum packed cooked ham was investigated by using culture-dependent and -independent approaches. Total microbial DNA was directly extracted from both control and treatment samples, and subjected to a nested PCR protocol, PCR-DGGE analysis was used to identify and monitor the dynamic changes in the microbial population, followed by partial 16S rDNA sequencing. The DGGE profile demonstrated that the protective culture effectively suppressed growth of predominant spoilage bacteria L. sakei, Lactobacillus curvatus and Leuconostoc mesenteroides in cooked ham during storage at 4°C, however, growth of uncultured Leuconostoc was not inhibited. The shelf-life of this product inoculated with L. sakei B-2, at levels of 5.91±0.04log(10)CFUg(-1) was 35 days, compared to 15 days of control samples, when the ham was stored at 4°C.