Influence of Enterococci and Lactobacilli on Listeria

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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.

Section: Resultsmentioning

confidence: 98%

Antilisterial activity of lactic acid bacteria against Listeria monocytogenes strains originating from different sources

Složilová¹,

Purkrtová²,

Kosová³

et al. 2014

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“…The e. mundtii 1282 strain isolated from goat raw milk had previously shown antilisterial activity against l. innocua (12 strains) and l. monocytogenes CCM5576 due to the production of ELS (Kučerová et al 2009). Thus, this strain was selected for further experiments.…”

Section: Resultsmentioning

confidence: 99%

Characterisation of antilisterial bacteriocin-like substance produced by Enterococcus mundtii

Solichová¹,

Složilová²,

Jebava³

et al. 2012

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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.

“…The cultures were centrifuged at 6000 rpm for 15 min; the cell-free supernatant was neutralised to pH 6.0 using NaOH (100 g/l solution) and heated at 90°C for 10 min to inactivate the remaining cells. The cell-free, neutralised supernatant (CFNS) was used in further bacteriocin assay by the above mentioned agar spot method (Kučerová et al 2009b).…”

Section: Enterococcimentioning

confidence: 99%

Bacteriocin activity of enterococci and presence of genes related to pathogenesis

Trivedi¹,

Sedmíková²,

Karpíšková³

2012

Trivedi K., Sedmíková R., Karpíšková R. (2012): Bacteriocin activity of enterococci and presence of genes related to pathogenesis. Czech J. Food Sci., 30: 330-335.In total 228 enterococci strains isolated from food were studied. enterococcus faecalis, e. faecium, and e. casseliflavus were found to be the dominant strains while e. durans and e. mundtii were present in a smaller extent. Antimicrobial activity determined by double layer technique revealed that 150 (65.7%) strains showed antimicrobial activity against the individual tested pathogenic strains of Listeria monocytogenes, Staphylococcus aureus, and methicilin resistant S. aureus (MRSA). Cell-free neutralised supernatants (CFNS) were prepared from 150 potential bacteriocin producers. Of these 150, CFNS 107 (71.3%) strains were active in the bacteriocin production against one or more pathogenic strains tested. S. aureus and MRSA were found to be more sensitive to the antimicrobial substances than L. monocytogenes. Multiplex PCR for the detection of seven virulence genes in bacteriocin producing strains showed that 47.6% of strains were able to amplify one or more virulence genes. e. faecalis was the most virulent species. The presence of tyrdc gene was seen in all bacteriocin producing strains. None of the strains carried genes encoding the resistance to vancomycin.