Molecular Detection of the Plantaricin A (plnA) Gene in the Lactobacillus casei Group

The plantaricin A (plnA) gene encodes a pheromone peptide that induces the synthesis of bacteriocins in Lactobacillus plantarum but can also be found in other species. Lactobacillus casei, Lactobacillus paracasei, and Lactobacillus rhamnosus are the most commonly studied and used probiotics for the synthesis of antimicrobial compounds such as bacteriocins. This study specifically focused on detecting the presence of the plnA gene, a single gene associated with plantaricin synthesis, in the L. casei group. Detection of the plnA gene was carried out through bacterial culturing, direct colony PCR, PCR amplification using plnA-F and plnA-R specific primers, electrophoresis, sequencing, and sequence analysis using BLAST. The presence of bands in the electrophoresis of PCR results revealed that the plnA gene was not detected in L. rhamnosus, but was found in L. casei and L. paracasei. Sequencing analysis of the plnA gene from L. casei and L. paracasei revealed 99.56% and 100% similarity with the plnA gene from L. plantarum EG.LP.18, respectively. The plnA gene found in Lactobacillus casei and Lactobacillus paracasei can be used to produce bacteriocins, which are antibacterial compounds.