Molecular characterization of native isolates of lactic acid bacteria,bifidobacteria and yeasts for beneficial attributes

In a changing scenario of food habits being associated with wellness factors through the concepts of probiotics and prebiotics, an attempt has been made to characterize on molecular basis, the desirable benefits associated with natural isolates of lactic acid bacteria, bifidobacteria, and yeasts. From a diverse range of foods and related samples, based on conventional microbiological protocols, three well-characterized natural isolates of Lactobacillus plantarum MTCC 5422, Bifidobacterium adolescentis MTCC 5423 and Saccharomyces cerevisiae MTCC 5421 were selected. The cultures of L. plantarum and B. adolescentis showed positive polymerase chain reaction (PCR) amplification with oligonucleotide primers targeting genus-specific 16 S rRNA for Lactobacillus and fructose-6-phosphate phosphoketolase for Bifidobacterium. Similarly, species-specific positive amplification in PCR was observed with primers of phytase (acid phosphatase) in S. cerevisiae and α-d-galactosidase and bile salt hydrolase in L. plantarum and B. adolescentis. The cultures of L. plantarum and B. adolescentis exhibited a broad spectrum antibacterial activity against selected foodborne pathogenic bacterial species and tolerance to acid and bile. Gene sequence of respective PCR-amplified products confirmed the genetic identity of the isolated cultures as L. plantarum and B. adolescentis showing 99% homology with the documented sequence of established gene bank.