Fourteen Lactobacillus plantarum strains isolated from various food sources and two different climatic regions, Ireland and Pakistan were analyzed for their probiotic functions. RecA gene based multiplex PCR amplifications and pulsed-field gel electrophoresis (PFGE) were performed to genetically characterize these strains at subspecies level. All the strains were tested for bacteriocin activity against major food borne pathogens (L. innocua and L. monocytogenes). Bacteriocin was further purified using HPLC and identified with MALDI TOF MS analysis. Identification of gene encoding plantaracin 423 along with its enzyme sensitivity assays to protinease K and pepsin were also performed. Probiotic properties of bacteriocin producing strains were also analyzed by acid tolerance, bile salt tolerance, survival in simulated gastric juice and antibiotic resistance tests. Ten distinctly different strains of PFGE patterns were identified following ApaI digestion. Antimicrobial screening showed five L. plantarum strains as the potential producers of bacteriocin, expressing GIZ (Growth inhibition zone) up to 12, 12, 14, 11 and 13 mm, respectively against L. innocua. Molecular characterization of these strains further exhibited that plantaracin gene was present in the genome of L. plantarum strains AS-4, AS-6, AS-7, AS-13 and AS-14. All strains presented significant in vitro functional probiotic potential. Current study therefore, not only highlights bacteriocin regulated probiotic potential of L. plantarum strains isolated from different sources and climatic regions but also designates high heterogeneity in functional properties of the L. plantarum strains.
Keywords: Functional probiotics properties; Genetic variability; Lactobacillus plantarum; Plantaracin.
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