Novel Identification Methods Including a Species-Specific PCR for Hazardous Bacillus Species

Fifteen strains of Bacillus spp. (three B. cereus strains, one B. subtilis, B. macerans, B. pumilus, and B. mycoides strains, and eight unknown isolates from the food-industry) were identified on species level with three designed pairs of primers for B. cereus, B. licheniformis, and B. subtilis. Primers designed for B. licheniformis (BlichF and BlichR) and B. subtilis (BsubF and BsubR) allowed specific species identification, whereas the designed pair of primers for B. cereus (BcerF2 and BcerR2) showed specificity for B. cereus sensu lato, because both B. cereus strains and B. mycoides gave positive reaction. Bacilli identification was also carried out with routine API method with unsatisfactory results. The (GTG) 5-PCR method was used for strain characterization, enabling bacilli classification into separate clusters according to their taxonomic designations

Quantification of Lactobacillus helveticus in a mixture of lactic acid bacteria using qPCR in cheese

Conventional quantification of L. helveticus, in presence of other lactobacilli species, using classical plate method employing low selective media is very inaccurate. Determination of L. helveticus using quantitative PCR (qPCR) was performed in six artisanal Kazakh soft cheeses made from cow’s milk or from a mixture of cow’s and goat’s milk. L. helveticus was quantified by species-specific qPCR, monitoring the presence of genes encoding for peptidoglycan hydrolases. Quantification of L. helveticus based on qPCR ranged from 2.6×106 to 4.1×108 CFU·g−1 according to the type of the cheese. The microflora of cheese consisted of a mixture of starter and non-starter lactic acid bacteria