LACTOBACILLUS STRAINS FROM APPLE AND FERMENTED MILK AND THEIR PROBIOTIC PROPERTIES

In this study, twenty isolates of lactic acid bacteria (LAB) from different apple varieties were obtained. Their probiotic properties together with those of 12 strains, isolated by us earlier from fermented milk, Levilactobacillus brevis (10, 15, 18, 49, 51), Lactiplantibacillus pentosus (40, 57, 63, 85, 88, 92) and Lactobacillus fermentum (44) were studied. Apple Lactiplantibacillus plantarum 52, 53, 74, and 76 were found to be pH 2-resistant during incubation for 30, 60 and 90 min. Overall, exposure to bile salts (0.3%; 0.5%; 1%; and 1.5%) had no effect on the growth of Lactobacillus sp. Antimicrobial activity and antibiotic resistance/susceptibility studies were performed on ten pathogenic microorganisms and nine antibiotics, respectively. Lactiplantibacillus (Lpb.) plantarum 52, 53, and 74 from apple samples had susceptibility to oxytetracycline, tetracycline, and rifampicin, Lpb. plantarum 52, 74 and 76 were susceptible to erythromycin. Almost all strains of lactobacillus showed antimicrobial activity to Enterococcus faecalis ATCC 29212, except Lpb. plantarum 76 and L. brevis 51. Lpb. plantarum 76 had inhibitory activity against Bacillus cereus ATCC 10876 (16.3 +/- 0.52), Klebsiella pneumoniae ATCC 13833 (16.4 +/- 0.4), Streptococcus pyogenes ATCC 21059 (16.3 +/- 0.3), Pseudomonas aeruginosa ATCC 27853 (16.3 +/- 0.4), Escherichia coli ATCCB322 (16.3 +/- 0.5), Proteus mirabilis ATCC 12453 (12.4 +/- 0.4), and Shigella flexneri ATCC 12022 (12.3 +/- 0.3). Based on the studied probiotic properties, apple Lpb. plantarum 52, Lpb. plantarum 53, Lpb. plantarum 74, Lpb. plantarum 76, identified by MALDI-TOF mass spectrometry and 16S rDNA sequencing, were selected as potential candidates for the fermentation of apple juices. Fermented apple juices could be a new source of probiotics for lactose intolerant and vegetarian consumers.