Abstract:Složilová I., Purkrtová S., Kosová M., Mihulová M., Šviráková E., Demnerová K. (2014): Antilisterial activity of lactic acid bacteria against Listeria monocytogenes strains originating from different sources. Czech J. Food Sci., 32: 145-151.Eight individual bacteriocin-producing lactic acid bacteria (LAB) strains and three bacteriocin-non-producing cheese starter cultures were evaluated for their ability to inhibit the growth of six Listeria monocytogenes strains, originating from the guinea-pig lymph nodes, raw cow milk, and manufacturing dairy equipment. Results showed that either live cells or cell-free neutralised supernatant (CFNS) and/or heated CFNS of six individual LAB strains (Lcc. lactis subsp. lactis CCDM 416 and NIZO R5, Lbc. plantarum HV 11 and DC 1246, P. acidilactici HV 12, and Ent. mundtii CCM 1282) and one starter culture (DELVO-ADD ® 100-X DSF) were effective in the suppression of at least one listeria strain. Neither any individual LAB strain nor starter culture was antagonistic toward all studied L. monocytogenes strains, indicating diverse sensitivity/resistance among L. monocytogenes strains to antimicrobial compounds of LAB. The significant susceptibility of listerias isolated from raw milk and dairy equipment together with the strong antilisterial activity of DELVO-ADD ® 100-X DSF could be applied in dairy technology, where commonly used starter cultures could play both the biopreservative and fermentation role.

Solichová K., Složilová I., Jebavá I., Uhrová B., Plocková M. (2012): Characterisation of antilisterial bacteriocin-like substance produced by Enterococcus mundtii. Czech J. Food Sci., 30: 89-97.The antilisterial activity of e. mundtii 1282 strain and its cell-free neutralised supernatant was observed against five persistent l. monocytogenes strains using the agar spot method. The enterococcal metabolite was consequently characterised as a proteinaceous substance -the bacteriocin-like substance, which was heat-stable at heating to 100°C for 30 min, stable at pH 2-12, and still active after eight-week long storage at 6°C and -20°C. The bacteriocin-like substance reached the highest activity of 6400 AU/ml after ten hours of cultivation of e. mundtii 1282 strain, when it was at the stationary phase of its growth. e. mundtii 1282 strain produced the bacteriocin-like substance: in BHI broth with pH 4-6, at the cultivation temperature 12-45°C, and in BHI broth with 1-6% (w/w) NaCl.

We report the draft genome sequence of the bacteriocin producer Enterococcus faecium strain CRL 1879, isolated from a northwestern Argentinian artisanal cheese. The draft genome sequence is composed of 73 contigs for 2,886,747 bp, with 3,140 protein-coding genes. Six biosynthetic clusters for bacteriocin class II production were found. Typical virulence determinants, which have relevance in food safety, were not present.

Abstract:The work was aimed at the growth suppression of cultured listerias strains by cultured lactococci strains or commercial mesophilic cheese cultures during common cultivations in the model UHT milk system (0.5% w/w of milk fat content) at 30°C during 18 h aerobically. Milk was primarily fermented by lactococci at the level of 10 8 CFU/ml and secondarily contaminated by listerias at the level of 10 3 CFU/ml. The most intensive growth suppressions of both Listeria innocua (CCM 5884 or Ln-03) strains were caused by Lactococcus lactis subsp. lactis (LCC 416 or CHCC 2281) strains or DELVO-ADD ® 100-X DSF cheese culture; the listerias growth reductions was from the level of 10 3 CFU/ml to 10 0 CFU/ml. Obtained results should be applied to dairy industry provided that HACCP, GHP and GMP systems must be observed. Bacteria of Listeria genus attract an attention because of the health safety of final products, especially secondarily ripening cheeses, in the dairy industry of the Czech Republic and the European Union (EU). The majority of listerias species are harmless. L. monocytogenes (LM) species is pathogenic for human with 20% of death on listeriosis (Macela et al. 2006). L. ivanovii species is pathogenic just for sheep (Batt 2000). LM represents a facultative intracellular pathogen, which infects hosts by alimentary way (Schech 1983). Raw milk produced in milk farms represents a danger source of LM contamination as long as it is obtained during milking under GMP non-performance. In dairies raw milk is treated by heat with a guarantee LM inactivation. Final products can be secondarily contaminated by LM under conditions of sanitation regimes defaults or production control errors with the assistance of HACCP system. Listerias are able to reproduce at low storage temperatures and because of long incubation period of listeriosis it is difficult to prove whether a final product was contaminated at a producer or at a consumer only. For that reason naturally ways of listerias elimination are found. For example lactic acid bacteria can reduce or inhibit listerias and show rich biochemical activities. KeywordsThere are various products with antilisterial effect on the market of the Czech Republic and the EU. Listex TM P100 is a well-known and described commercial product that contains a virulent strictly lytic phage of P100 type, which shows a high specificity against LM (Carlton 2005).The aim of this work was to check a biochemical potential of lactococci for the reduction of listerias' growth in the model UHT milk system. Cultivation conditions of used strains. Lactococci and cheese cultures were cultivated in M17 broth with lactose (0.5% w/w) (LM17 broth) at 30°C for 18 h aerobically. Listerias were cultivated in BHI broth at 30°C for 18 h aerobically. All strains were also cultivated in UHT milk (0.5% w/w of milk fat content) with/ or without addition of yeast extract (YE) (0.5% w/w) at 30°C for 18 h aerobically. For work were used 1% (v/w) inocula. MATEriAlS And METHodS StrainsEstimation of lactococci and listerias...