Author(s): Megha Tanaji Jadhav and B Narayanaswamy

Abstract: The objective of this study was to isolate, identify and characterize lactic acid bacterial strains from beet root and sweet corn as potential probiotics with antimicrobial activity against some human pathogenic strains. A total of 36 bacterial strains were isolated and morphologically these isolates were rods, cocci, cocco-bacilli in shape with small-medium milky white, creamy colonies; biochemically Gram positive, negative for catalase and endospore production test, positive for exopolysaccharide production and acid production test. None of the isolates including reference strains (Lactobacillus acidophilus MTCC10307 and Lactobacillus plantarum NCIM 2656) produced gas in Durham’s tube and hence characterized as homofermentative lactic acid bacteria. Further these isolates were then screened for their probiotic activities. Results showed that some of these isolates were viable at varied pH (2-3), 0.1-0.4% bile salt concentrations and displayed marked phenotypic resistance against the antibiotics like Kanamycin, Streptomycin, Ciprofloxacin and Gentamycin and low-level resistance to Tetracycline, Chloramphenicol, Ampicillin and Azithromycin. In addition, these isolates also showed good antimicrobial activities against the tested pathogenic strains of humans. Out of 3 selected lactic acid bacterial isolates, BRLB22 and SCLB12 isolates showed maximum zone of inhibition against Staphylococcus aureus and Escherichia coli followed by other isolates. Finally, the best two selected LAB isolates (SCLB12 and BRLB22) were identified as Lactobacillus brevis and Lactobacillus plantarum respectively by molecular and phylogenetic analysis using 16S rRNA gene based molecular method.

DOI: 10.33545/26174693.2024.v8.i3a.678