Bacteriocinogenic Activity of Lactobacilli Isolated from Cheese and Baby Faeces
Bojana Bogovič Matijašić* and Irena Rogelj
University of Ljubljana, Biotechnical Faculty, Zootechnical Department, Institute for Dairying, 1230 Dožmale, Groblje 3, Slovenia
Received May 6, 1998
Accepted February 15, 1999
bacteriocin, Lactobacillus acidophilus LF 221
Lactobacillus strains, isolated from cheese (30 strains) and from baby faeces (41 strains) were examined for bacteriocin production, by deferred agar spot (DAS) test and by agar well diffusion (AWD) assay, using 29 Gram-positive test strains from different genera. Eight cheese isolates and 2 human isolates showed antimicrobial activity against at least one test strain. The proteinaceous nature of the inhibitor was confirmed in four cheese isolates and in both human isolates (LF221 and K7). Human isolates also inhibited some non-LAB bacteria. Strain Lactobacillus acidophilus LF221 was additionally tested by AWD assay against a wide range of bacteria, including pathogens. Besides some lactic acid bacteria test strains, particular strains of the following species were also inhibited: Listeria innocua, Enterococcus faecalis, Bacillus cereus, Staphylococcus aureus and Clostridium sp. The inhibitor was found to be a heat stable protein, as it was inactivated by trypsin, proteinase K, pronase and was resistant to heat (100 °C). Strain L. acidophilus LF221 was bactericidal, but not bacteriolytic to Lactobacillus helveticus ATCC 11509. Bacteriocin molecules were present in the supernatant in the form of aggregates with relative molecular masses exceeding 150 kDa.
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