Molecular identification of L. delbrueckii subsp. bulgaricus using multiplex PCR assay. Lanes 1 and 2 correspond to samples derived from two different commercial yogurts containing L. delbrueckii subsp. bulgaricus (labeled as such), lanes 3 and 4 correspond to samples prepared in the lab and lane 5 corresponds to a sample derived from a commercial food supplement containing L. delbrueckii subsp. bulgaricus (labeled as such). Lane 6 that corresponds to a sample prepared in the lab lacking L. delbrueckii subsp. bulgaricus served as a negative control.