Analysis of lactic acid bacteria from Moldovan cheese "Brynza" using 16S rRNA

Abstract

In our study, we examined the microflora of Moldovan type of cheese “Brynza” using molecular biology techniques. To confirm the genus classification, we employed genus-specific PCR, which revealed that all isolates belonged to the Lactobacillus sp. and Streptococcus sp. groups. Selected strains were analyzed using RAPD and Rep-PCR typing methods, which are more cost-effective alternatives to sequencing. However, t hese methods did not allow for proper classification of the strains according to their taxonomic hierarchy. Using sequencing techniques, we identified and confirmed the genus of the selected strains, which were then used for further analysis. We found the differences between PCR results and previous identification of LAB

strains based on biochemical phenotypic signs. The 4A strain was originally identified as Lactobacillus bulgaricus but sequencing revealed it to be a Lactobacillus fermentum. We identified strain ST144 and LB12 as Streptoccus thermophilus. Strains 10A and 6B were originally identified as Lactobacillus acidophilus, whereas based on PCR data, they are strains of Lactobacillus bulgaricus Lactobacillus plantarum. Strains 177 were originally assigned to the genus Leuconostoc, but by sequencing we found that it is a strain Leuconostoc mesenteroides. As a result of the research, several limitations were identified in the

biochemical methods used for determining the species affiliation of lactic acid bacteria. Modern molecular techniques offer significantly greater accuracy in species identification, ensuring more

reliable and precise classification.