Application of Enterococcus faecium KE82, an enterocin-A-B-P-producing strain, as an adjunct culture enhances inactivation of Listeria monocytogenes during traditional PDO Galotyri cheese processing

2020 ◽  
Author(s):  
Nikoletta Sameli ◽  
Panagiotis N Skandamis ◽  
John Samelis
Keyword(s):  
Listeria Monocytogenes ◽  
Enterococcus Faecium ◽  
Fermentation Process ◽  
Streptococcus Thermophilus ◽  
Milk Fermentation ◽  
Dairy Plant ◽  
Ewe's Milk ◽  
Cheese Curd ◽  
Enterocin A ◽  
Adjunct Culture

The ability of the enterocin-A-B-P-producing Enterococcus faecium KE82 adjunct strain to inactivate Listeria monocytogenes during Galotyri PDO cheese processing was evaluated. Three artisan cheese trials from traditionally ‘boiled’ (85oC) ewe’s milk were processed. The milk cooled at 42oC was divided in two parts: A1 was inoculated with Streptococcus thermophilus ST1 and Lactococcus lactis subsp. cremoris M78, and A2 with the basic starter ST1+M78 plus the KE82 adjunct (step 1). All milks were fermented at 20-22oC for 24 h (step 2); the curds were drained at 12oC for 72 h (step 3) and then salted with 1.5-1.8% salt to obtain the fresh Galotyri cheeses (step 4), which were ripened at 4oC for 30 days (step 5). Because an artificial listerial contamination in the dairy plant was prohibited, A1 and A2 cheese milk (200-mL) or curd (200-g) portions were taken after steps 1 to 5, inoculated (3-4 log CFU/mL or g) with L. monocytogenes no.10, incubated at 37, 22, 12, and 4oC for predefined periods, and analyzed microbiologically and for pH. L. monocytogenes declined without growth in all cheese curd portions contaminated after steps 2 to 5 (pH 4.36 to 4.84), when stored at 4 or 12oC for 15 days. The final net reductions of Listeria populations were by 2.00, 1.07, 0.54 and 0.61 log units higher in the A2 than A1 curd portions after steps 2, 3, 4 and 5, respectively. As regards step 1 conducted in simulation of the whole cheese milk fermentation process, L. monocytogenes declined by 1.47 log units more in the A2 than A1 milk portions after 72 h at 22oC; however, a slight (0.6-log) growth was preceded during the first 6 h at 37oC. In conclusion, E. faecium KE82 showed growth compatibility with the starter and enhanced inactivation of L. monocytogenes across Galotyri cheese processing. Combined acid-enterocin antilisterial effects were the weakest in the fermenting milks, turned to the strongest in the unsalted fermented curds, and reduced in the salted fresh cheeses.

Survival of Listeria monocytogenes in Frozen Ewe's Milk and Feta Cheese Curd

1997 ◽  
Vol 60 (9) ◽  
pp. 1041-1045 ◽  
Author(s):  
DEMETRIOS K. PAPAGEORGIOU ◽  
MINA BORI ◽  
ANTONIOS MANTIS
Keyword(s):  
Listeria Monocytogenes ◽  
Death Rate ◽  
Standard Procedure ◽  
Freeze Thaw ◽  
Milk Samples ◽  
Ph Values ◽  
Feta Cheese ◽  
Ca 50 ◽  
Ewe's Milk ◽  
Cheese Curd

Pasteurized whole ewe's milk was inoculated to contain ca. 1.0 × 106 to 2.0 × 106 Listeria monocytogenes Scott A or California (CA). Inoculated milk samples of 200 ml in sterile stomacher bags were frozen at −38°C and stored at −18 or −38°C for 7.5 months. Inoculated milk was also made into Feta cheese curd, according to a standard procedure. After 5 h of drainage, curd samples of 200 g in sterile stomacher bags were frozen at −38°C, and stored at −18 or −38°C for 7.5 months. The pH values of the ewe's milk and Feta cheese curd before freezing were 6.70 and 5.43 respectively. At l5-day intervals samples were thawed at 35°C and tested for numbers of L. monocytogenes cells by surface plating on tryptose agar (TA) and tryptose salt agar (TSA) for ewe's milk samples, or on lithium chlorite phenylethanol moxalactam agar (LPMA) for curd samples. A high percentage (ca. 95%) of L. monocytogenes Scott A cells survived during storage of frozen ewe's milk at −18 or −38°C for 7.5 months. The population of L. monocytogenes CA decreased by ca. 50 and 40% during storage of frozen ewe's milk for 7.5 months at −18 and −38°C respectively. The death rate of L. monocytogenes increased after repeated freeze-thaw cycles of ewe's milk at −18 or −38°C. Populations of L. monocytogenes Scott A decreased by ca. 40% in the center of the cheese curd samples but the rate of death was less than ca. 17% on the surface of the frozen cheese curd samples during storage at −38°C for 7.5 months. Populations of strain Scott A decreased by ca. 57% in the center of the cheese curd samples and by ca. 22% on the surface of the frozen cheese curd samples during storage at −18°C for 7.5 months. Populations of L. monocytogenes CA decreased by ca. 98% for samples both at the center and the surface of the frozen curd during storage at −38 or −18°C for 7.5 months.

Enhanced Control of Listeria monocytogenes by Enterococcus faecium KE82, a Multiple Enterocin–Producing Strain, in Different Milk Environments

2016 ◽  
Vol 80 (1) ◽  
pp. 74-85 ◽  
Author(s):  
ELPINIKI VANDERA ◽  
ALEXANDRA LIANOU ◽  
ATHANASIA KAKOURI ◽  
JINBO FENG ◽  
ANNA-IRINI KOUKKOU ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Enterococcus Faecium ◽  
Starter Culture ◽  
Streptococcus Thermophilus ◽  
Raw Milk ◽  
Pcr Analysis ◽  
Dairy Foods ◽  
Reverse Transcription Pcr

ABSTRACT Enterococcus faecium KE82, isolated from traditional Greek Graviera cheese, was identified in pure broth cultures in vitro as a multiple enterocin–producing bacterial strain possessing the structural entA, entB, and entP enterocin genes. E. faecium KE82 was further assessed for in situ antilisterial activity in raw milk (RM) and commercially thermized milk (TM; 63°C for 30 s) in the presence of the indigenous microbiota and in sterile raw milk (SRM; 121°C for 5 min) with or without the addition of two commercial starter culture (CSC) strains Streptococcus thermophilus and Lactococcus lactis. Growth of Listeria monocytogenes was completely inhibited in RM incubated at 37°C for 6 h, whereas the pathogen was significantly inactivated in RM+KE82 samples during further incubation at 18°C for 66 h. In contrast, L. monocytogenes levels increased by approximately 2 log CFU/ml in TM, but in TM+KE82 samples, pathogen growth was retarded during the first 6 h at 37°C followed by growth cessation and partial inactivation at 18°C. After 48 to 72 h, growth of L. monocytogenes in SRM+CSC samples decreased by 4 to 5 log CFU/ml compared with the SRM control, whereas additional 10-fold decreases in the pathogen were observed in SRM+CSC+KE82 samples. Reverse transcription PCR analysis of SRM+KE82 and SRM+CSC+KE82 samples confirmed that the entA and entB genes were transcribed, but entP gene transcription was not detected. All RM and SRM samples inoculated with E. faecium KE82 displayed strong in situ inhibitory activity against L. monocytogenes in well diffusion bioassays, whereas activity was weaker to undetectable in comparable or additional TM+KE82 samples; no milk sample without E. faecium KE82 had activity against L. monocytogenes. The findings of this study indicate that E. faecium KE82 is an antilisterial agent that could be used in traditional dairy foods because it concomitantly produces enterocins A and B in situ in milk.

Control of Listeria monocytogenes in Goat's Milk and Goat's Jben by the Bacteriocinogenic Enterococcus faecium F58 Strain

2006 ◽  
Vol 69 (10) ◽  
pp. 2370-2376 ◽  
Author(s):  
FOUAD ACHEMCHEM ◽  
JAMAL ABRINI ◽  
MANUEL MARTÍNEZ-BUENO ◽  
EVA VALDIVIA ◽  
MERCEDES MAQUEDA
Keyword(s):  
Listeria Monocytogenes ◽  
Enterococcus Faecium ◽  
Decarboxylase Activity ◽  
Producer Strain ◽  
Reduced Fat ◽  
Goat’S Milk ◽  
Whole Milk ◽  
Goat's Milk ◽  
Adjunct Culture

The bacteriocinogenic Enterococcus faecium F58 strain, a natural goat's jben cheese isolate, lacks decarboxylase activity involved in most biogenic amine formation. It was also sensitive to 13 antibiotics assayed and free of virulence and vancomycin resistance genes. The F58 strain reached the stationary phase after 12 h of growth in sterile goat's milk, and the production of enterocin F-58 (Ent L50) was first detected after 48 h (400 AU/ml), thereafter remaining stable up to 5 days. The effectiveness of the F58 strain in controlling Listeria monocytogenes serovar 4b in reduced fat and whole goat's milk, and in goat's jben has been examined. Coculture experiments of F58–L. monocytogenes in both types of milk demonstrated that listeriae were not eliminated, although reductions by 1 to 4 log units were found. Nevertheless, when the F58 strain was previously inoculated in whole milk and left to grow for 12 h before contamination, the pathogen was completely eliminated after 130 h of coculture. Production of jben cheese contaminated with L. monocytogenes prior to packaging, using preparations of F58-producer strain, caused a significant decrease in the number of viable listeriae, which were undetectable after 1 week of cheese storage at 22°C. Altogether, results from this study suggest that E. faecium F58 strain may be used as an adjunct culture in cheese to control contamination and growth of L. monocytogenes by in situ enterocin production, thus providing an additional hurdle to enhance control of this pathogen.

scholarly journals In Vivo Bioavailability of Selenium in Selenium-Enriched Streptococcus thermophilus and Enterococcus faecium in CD IGS Rats

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 463
Author(s):  
Gabriela Krausova ◽  
Antonin Kana ◽  
Marek Vecka ◽  
Ivana Hyrslova ◽  
Barbora Stankova ◽  
...  
Keyword(s):  
Glutathione Reductase ◽  
Enterococcus Faecium ◽  
Reductase Activity ◽  
Streptococcus Thermophilus ◽  
Heart Tissue ◽  
Sprague Dawley ◽  
Glutathione Reductase Activity ◽  
Novel Concept ◽  
The Individual

The selenium (Se) enrichment of yeasts and lactic acid bacteria (LAB) has recently emerged as a novel concept; the individual health effects of these beneficial microorganisms are combined by supplying the essential micronutrient Se in a more bioavailable and less toxic form. This study investigated the bioavailability of Se in the strains Enterococcus faecium CCDM 922A (EF) and Streptococcus thermophilus CCDM 144 (ST) and their respective Se-enriched forms, SeEF and SeST, in a CD (SD-Sprague Dawley) IGS rat model. Se-enriched LAB administration resulted in higher Se concentrations in the liver and kidneys of rats, where selenocystine was the prevalent Se species. The administration of both Se-enriched strains improved the antioxidant status of the animals. The effect of the diet was more pronounced in the heart tissue, where a lower glutathione reductase content was observed, irrespective of the Se fortification in LAB. Interestingly, rats fed diets with EF and SeEF had higher glutathione reductase activity. Reduced concentrations of serum malondialdehyde were noted following Se supplementation. Diets containing Se-enriched strains showed no macroscopic effects on the liver, kidneys, heart, and brain and had no apparent influence on the basic parameters of the lipid metabolism. Both the strains tested herein showed potential for further applications as promising sources of organically bound Se and Se nanoparticles.

scholarly journals Susceptibility to Enterocins and Lantibiotic Bacteriocins of Biofilm-Forming Enterococci Isolated from Slovak Fermented Meat Products Available on the Market

2020 ◽  
Vol 17 (24) ◽  
pp. 9586
Author(s):  
Andrea Lauková ◽  
Anna Kandričáková ◽  
Eva Bino
Keyword(s):  
Enterococcus Faecalis ◽  
Enterococcus Faecium ◽  
Biofilm Formation ◽  
Food Industry ◽  
Meat Products ◽  
Low Grade ◽  
Enterococcus Hirae ◽  
Conventional Antibiotics ◽  
Enterocin A

This study investigated eight types of Slovak dry fermented meat products (salami and sausages) that are available on the market and were produced by three different producers in different regions of Slovakia. The total counts of enterococci in these products ranged from 2.0 up to 6.0 cfu/g (log10). Three species were identified among the 15 selected enterococcal strains; Enterococcus faecium (8 strains), Enterococcus faecalis (3) and Enterococcus hirae (4). They were hemolysis-negative (γ-hemolysis) with a biofilm-forming ability, which was evaluated as low-grade biofilm formation, susceptible to conventional antibiotics and mainly susceptible to lantibiotic bacteriocins, namely, gallidermin and nisin; they even showed a higher susceptibility to gallidermin than to nisin. They were also susceptible to enterocin–durancin, but most strains showed resistance to enterocin A/P. This study indicated that bacteriocins can play a key role in preventing and/or protecting from undesirable bacterial multiplication or contamination in the food industry and that they have great potential for further experimental applications.

Anti-adhesion of probiotic Enterococcus faecium WEFA23 against five pathogens and the beneficial effect of its S-layer proteins against Listeria monocytogenes

2019 ◽  
Vol 65 (3) ◽  
pp. 175-184
Author(s):  
Yao He ◽  
Xiongpeng Xu ◽  
Fen Zhang ◽  
Di Xu ◽  
Zhengqi Liu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Enterococcus Faecium ◽  
Probiotic Strain ◽  
Antagonistic Activity ◽  
Bacterial Surface ◽  
Colony Forming Units ◽  
Infant Feces ◽  
Adhesion Activity ◽  
Displacement Assays ◽  
Different Levels

Enterococcus faecium WEFA23 is a potential probiotic strain isolated from Chinese infant feces. In this study, the antagonistic activity of E. faecium WEFA23 on adhesion to pathogens was investigated. Enterococcus faecium WEFA23 was able to compete, exclude, and displace the adhesion of Escherichia coli O157:H7, Salmonella Typhimurium ATCC 13311, Listeria monocytogenes CMCC54007, Staphylococcus aureus CMCC26003, and Shigella sonnei ATCC 25931 to Caco-2 cells. Among them, L. monocytogenes achieved the strongest inhibition rate in both competition and displacement assays. Those anti-adhesion capacities were related to the bacterial physicochemical properties (hydrophobicity, auto-aggregation, and co-aggregation) of the bacterial surface. For L. monocytogenes, the anti-adhesion capacity was affected by the heat treatment, cell density, and growth phase of E. faecium WEFA23; 108 colony-forming units of viable cells per millilitre at the stationary phase exhibited the strongest anti-adhesion activity. In addition, removal of S-layer proteins of E. faecium WEFA23 by treatment with 5 mol/L LiCl significantly decreased its adhesion capacity, and those S-layer proteins were able to compete, displace, and exclude L. monocytogenes at different levels. Both cells and S-layer proteins of E. faecium WEFA23 significantly reduced the apoptosis of Caco-2 cells induced by L. monocytogenes, which was mediated by caspase-3 activation. This study might be helpful in understanding the anti-adhesion mechanism of probiotics against pathogens.

scholarly journals Importance of Enterococcus spp. for Forming a Biofilm

2009 ◽  
Vol 27 (Special Issue 1) ◽  
pp. S354-S356 ◽  
Author(s):  
L. Necidová ◽  
B. Janštová ◽  
S. Karpíšková ◽  
Š. Cupáková ◽  
M. Dušková ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Enterococcus Faecium ◽  
Biofilm Formation ◽  
Dairy Products ◽  
Formation Potential ◽  
Farm Level ◽  
Milk Samples ◽  
Bulk Milk ◽  
Dairy Plant ◽  
Plant Level

The aim of this study was to monitore the capability of <I>Enterococcus fecalis</I> and <I>Enterococcus fecium</I> to form biofilms. Enterococci isolates originated from individual milk, bulk milk samples and environmental swabs obtained at farm level, dairy plant level including semi and final dairy products. Biofilm formation potential was determined by growing the tested strains in glas tubes containing BHI medium. The capability of forming biofilms was detected in 28% of <I>Enterococcus</I> spp. strains. Higher number of biofilm forming strains of the <I>Enterococcus faecium</I> (33%) than <I>Enterococcus faecalis</I> (28%) has been registered. Isolates obtained at plant level were forming biofilms more often than isolates from plant level and in final products (cheese and curd cheese), no isolate has been seen to be able to form biofilm.

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