Title : Isolation and characterization of lactic acid bacteria from indian pickles and analysis of their food-related and probiotic properties
Abstract:
Lactic Acid Bacteria (LAB) are found in diverse habitats such as plants, the human GI tract, and fermented foods and are also known for their probiotic properties. Indian pickles are not much explored for isolation of LAB and their characterization for potential applications. The aim of this work was to isolate LAB from Indian pickles and study their probiotic, food-related, and genomic properties. A total of 39 homemade pickle samples were collected from different regions of Maharashtra, and a total of 252 putative LAB were isolated. Five different species of LAB was identified using 16S rRNA gene sequencing, viz., Leuconostoc mesenteroids, Lactiplantibacillus plantarum, Lactobacillus delbrueckii subsp. bulgaricus, Lacticaseibacillus rhamnosus, and Weissella confusa. A set of 15 unique L. plantarum strains was subjected to further characterization. All strains were bile and acid tolerant, were able to acidify the skim milk, lacked hemolytic activity, and exhibited potential antibacterial activity against three food borne pathogens, Escherichia coli, Listeria monocytogenes, and Enterococcus faecalis. All strains were susceptible to ampicillin, azithromycin, gentamicin, penicillin, and streptomycin; one strain was susceptible to trimethoprim, and two stains were susceptible to co-trimoxazole and tetracycline. These L. plantarum strains were next assessed for their ability to ferment mango juice to understand their metabolomic influence by GC-MS analyses. Various value-added volatile and non-volatile antioxidants, antimicrobials, and aroma chemicals were found to be generated during fermentation in a strain-dependent manner. Whole genome sequencing of the strains revealed the presence of genetic determinants of hydroxybenzoic acid and hydroxycinnamic acid metabolism in 11 strains of L. plantarum. Further analyses for establishing genotype-phenotype correlations are in progress. Our work can provide novel indigenous L. plantarum strains for the possible development of probiotic and functional foods.
Keywords: Indian pickles, L. plantarum, functional foods, mango juice, metabolites
