Safety Evaluation, Biogenic Amine Formation, and Enzymatic Activity Profiles of Autochthonous Enterocin-Producing Greek Cheese Isolates of the Enterococcus faecium/durans Group

Abstract

Autochthonous single (Ent+) or multiple (m-Ent+) enterocin-producing strains of dairy enterococci show promise for use as bioprotective adjunct cultures in traditional cheese technologies, provided they possess no pathogenic traits. This study evaluated safety, decarboxylase activity, and enzymatic (API ZYM) activity profiles of nine Ent+ or m-Ent+ Greek cheese isolates previously assigned to four distinct E. faecium (represented by the isolates KE64 (entA), GL31 (entA), KE82 (entA-entB-entP) and KE77 (entA-entB-entP-bac31)) and two E. durans (represented by the isolates KE100 (entP) and KE108 (entP-bac31-cyl)) strain genotypes. No strain was β-hemolytic or harbored vanA and vanB or the virulence genes agg, ace, espA, IS16, hyl, or gelE. All strains were of moderate to high sensitivity to ampicillin, ciprofloxacin, chloramphenicol, erythromycin, gentamicin, penicillin, tetracycline, and vancomycin, except for the E. faecium KE64 and KE82 strains, which were resistant to erythromycin and penicillin. All cheese strains showed moderate to strong esterase-lipase and aminopeptidase activities and formed tyramine, but none formed histamine in vitro. In conclusion, all Ent+ or m-Ent+ strain genotypes of the E. faecium/durans group, except for the cyl-positive E. durans KE108, were safe for use as adjunct cultures in traditional Greek cheeses. Further in situ biotechnological evaluations of the strains in real cheese-making trials are required.

Assessment of the Spoilage Microbiota during Refrigerated (4 °C) Vacuum-Packed Storage of Fresh Greek Anthotyros Whey Cheese without or with a Crude Enterocin A-B-P-Containing Extract

“…Three autochthonous single (Ent+) or multiple (m-Ent+) enterocin-producing strain biotypes of E. faecium , originally isolated from traditional Greek Graviera cheese [ 35 ], recently genotyped, characterized for their enterocin-mediated activity in culture broth media and skim milk [ 36 ] and evaluated for their safety [ 37 ], were used. They were the EntA+ E. faecium KE64 (GenBank accession no.…”

“…They were the EntA+ E. faecium KE64 (GenBank accession no. MW644963), the m-Ent+ ( entA-entB-entP ) E. faecium KE82 (MW644969) and the m-Ent+ ( entA-entB-entP ) E. faecium KE118 (not yet deposited in GenBank) [ 37 ]. The strains were activated from their frozen (−30 °C) stock state in de Man, Rogosa, Sharpe (MRS) broth (Lab M, Heywood, UK), with 20% glycerol, by adding 0.1 mL of each stock culture in 10 mL MRS broth incubated at 30 °C for 24 h and then subcultured twice, as above.…”

Microbiome Associated with Slovak Traditional Ewe’s Milk Lump Cheese

“…The genus Enterococcus belonging in the family Enterococcacae was detected in tested cheeses in the amount of 3.18% (Figures 1 and 3). On the one hand, enterococci can be supposed to be contaminant bacteria in cheeses [16][17][18]; on the other hand, they can serve as probiotic microbiota producing antimicrobial active substances-bacteriocins [2,19]. However, representatives of the genus Staphylococcus are supposed to be frequent inhabitants in cheeses [4,20].…”

Enterococci in Farm-Manufactured Pecorino and Goat Cheese

“…Regardless these considerations Enterococci are commonly found in milk and cheese [13] and there are two divergent opinions about the presence of enterococci in cheese. One is that enterococci should be considered more suitable than others groups commonly used as indicators of unhygienic procedures in food processing and handling (e.g.…”