title: Succession of dominant and antagonistic lactic acid bacteria in fermented cucumber: insights from a PCR-based approach.
abstract: The goal of the investigation was to study the succession of major groups of lactic acid bacteria (LAB) and their antagonism in salt-fermented cucumber using PCR. In a direct detection method as well as a short enrichment process, PCR enabled detection of Leuconostoc and Lactobacillus during early hours of fermentation. Subsequently, Lactobacillus and Pediococcus emerged as the dominant genera. Nucleic acid sequence of culture-independent clones confirmed the detection of Pediococcus as a dominant genera emerging during late stages of fermentation. PCR also revealed time-dependent emergence of mesentericin, pediocin and plantaricin A producers and accounted for the LAB succession in the fermenting samples. A total of 328 LAB isolates were obtained collectively from 30 cucumber samples, of which PCR could identify an overwhelming 186 Lactobacillus isolates followed by 113 Pediococcus and 29 Leuconostoc isolates, respectively. Based on antimicrobial assay against target strain Leuconostoc mesenteroides NRRL B640, 28% of the LAB were bacteriocin producers, of which pediocin producers were substantial, followed by plantaricin A and mesentericin producers. The bacteriocins elaborated by the isolates were active against a large number of Gram-positive target LAB strains and pathogenic bacteria including Bacillus cereus, Enterobacter aerogenes, Enterococcus faecalis, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam, India.
authors.forename: Atul Kumar
authors.initials: AK
authors.lastname: Singh
authors.forename: Aiyagari
authors.initials: A
authors.lastname: Ramesh
mesh_terms: D000898:Antibiosis; D001430:Bacteriocins / Q000096:biosynthesis; D015169:Colony Count, Microbial; D018553:Cucumis sativus / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005285:Fermentation; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D007778:Lactobacillus / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism; D007934:Leuconostoc / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism; D010376:Pediococcus / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods*; D013045:Species Specificity; D013997:Time Factors
chemical_list: D001430:Bacteriocins; D004269:DNA, Bacterial