Screening of Bacteriocin Production in Lactic Acid Bacteria Isolated From Fermented Dairy Products
Esra Demir
Department of Biology, Faculty of Arts and Science, Adnan Menderes University, 09010 Aydin, Turkey
Gamze Başbülbül *
Department of Biology, Faculty of Arts and Science, Adnan Menderes University, 09010 Aydin, Turkey
*Author to whom correspondence should be addressed.
Abstract
Aims: In this study we aimed to screen LAB strains from different fermented dairy products by phenotypic and genotypic methods.
Methodology: 138 LAB isolates belonging to Enterococcus (13,76%), Lactococcus (18,84%) and Lactobacillus (67,39%) genera from fermented dairy products were used to search for their bacteriocin production and bacteriocin encoding genes were searched. LAB isolates were screened by spot-on lawn assay method against indicator microorganisms. Geobacillus stearothermophilus DSMZ 22, Escherichia coli ATCC 35218, Bacillus cereus, Listeria innocua, Listeria monocytogenes, Enterococcus faecalis, Micrococcus luteus, Lactococcus lactis DSMZ 20729 and Lactobacillus plantarum DSMZ 20205. Cell-free supernatants (CFS) of LABs used for agar-well diffusion assay to confirm antibacterial activity.
Results: All the LAB strains exhibited antibacterial activity against indicator bacteria at varying degrees by spot on lawn method. None of the CFS except one belong to positive control Lactococcus lactis DSMZ 20729 showed inhibitory effect by agar well diffusion assay. According to PCR results which used to investigate the bacteriocin genes of LAB’s , ent-A (5,07%), ent-B (2,17%), lcn-A (2,17%), and pln (1,44%) genes were detected in some of the isolates.
Keywords: LAB, bacteriocin, spot-on lawn assay, agar well diffusion assay, PCR