Safety Evaluation of Enterocin Producer Enterococcus sp. Strains Isolated from Traditional Turkish Cheeses (original) (raw)
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Turkish Journal of Biology, 2013
In this study, the occurrence of enterocin genes, virulence factors, and antibiotic resistance in the bacteriocin-producer Enterococcus faecium EYT17, EYT31, and EYT39 strains was investigated. Polymerase chain reaction (PCR) studies showed that all of the E. faecium strains carried the enterocin A and B structural genes (entA and entB), while E. faecium EYT17 and EYT31 strains also carried the enterocin P structural gene (entP). None of the strains exhibited β-haemolysis or gelatinase activity. PCR analysis revealed that EYT17, EYT31, and EYT39 strains were clear of potential virulence determinants, except for ccf and efaAfm. The ccf gene was found in all of them. The efaAfm gene was only found in the EYT17 strain. All of the strains were found sensitive to ampicillin, chloramphenicol, gentamicin, norfloxacin, penicillin, streptomycin, tetracycline, sulphamethoxazole/trimethoprim, and vancomycin by disc diffusion method. E. faecium strains only exhibited intermediary resistance to erythromycin (15 µg). The results of this study showed that the multiple enterocin-producer E. faecium EYT17, EYT31, and EYT39 strains are safe and these strains may be used for food preservation.
Antimicrobial Activity Potential of Enterococcus spp. Isolated from Some Traditional Turkish Cheeses
Kafkas Universitesi Veteriner Fakultesi Dergisi, 2016
Enterococci can produce enterocins which have antimicrobial activity against Gram-positive and also Gram-negative pathogenic, toxigenic and food-spoilage bacteria. The aim of this study was to determine the antimicrobial activity of Enterococcus spp. isolated from traditional Turkish cheeses such as Kashar, Manyas, Sepet, Kelle, Mihalic, Tulum. The isolates were tested against Listeria monocytogenes, Listeria innocua, Listeria ivanovii, Staphylococcus aureus and Enterococcus faecalis and also detected the presence of entA and entB genes of these isolates. Total 66 of enterococcal isolates were obtained from 34 of cheese samples and 25 of these isolates showed antimicrobial activity against tested reference bacteria by using agar spotting method. Also it was determined most of Enterococcus spp. carried enterocin encoding entA and entB genes. We concluded that these isolates or their enterocins may have a potential for food preservation, however they should be evaluated in terms of food safety.
Characterization and safety evaluation of enterococci isolated from Spanish goats' milk cheeses
International Journal of Food Microbiology, 2009
Enterococci are common constituents of dairy products such as cheese, in which it is believed that they contribute to the development of some of their organoleptic properties. This is particularly true in the Mediterranean region, where farmhouse cheeses are generally made from raw milk, which tends to harbour enterococci. In recent years, however, enterococci have emerged as serious pathogens in hospital environments, where vancomycin-resistant strains are on the increase. In this study we have characterized 95 enterococci isolated from 3 different goats' milk cheeses, belonging to the species Enterococcus devriesei, Enterococcus faecalis and E. malodoratus, among others. Genomic typification by RAPD and ERIC-PCR showed that the genotypes tended to be specific to particular cheeses; only two of the different cheeses contained two genotypes. E. malodoratus showed the highest intraspecific diversity. No more than 13% of the isolates demonstrated any antimicrobial activity, most of these belonging to E. devriesei. Screening for the most important enterocin structural genes by dot-blot hybridization proved negative for enterocins A, B and P. All the isolates belonging to E. faecalis, E. hirae and E. avium, on the other hand, hybridized with the enterocin EJ97 gene probe and all the E. faecalis strains hybridized with the AS-48 and MR10A structural gene probes. The genes gelE, esp, asa1, efaA and ace, all associated to virulence factors in enterococci, were detected at different levels in E. faecalis whilst they were not detected in the remaining species studied. No resistance to vancomycin was detected by PCR screening. The gene for tyrosine decarboxylase (tdc) was detected in all the E. faecalis and E. hirae isolates but in none of the others.
A collection of Enterococci spp. (about 96 isolates) were isolated from two Iranian raw milk cheeses, known as Lighvan and Koozeh cheeses and identified as Ent. faecium, Ent. faecalis, Ent. durans, Ent. casseliflavus and Ent. italicus by 16S rDNA sequencing. These 96 isolates were subjected to Agar-spot and well-diffusion assay in order to detect the bacteriocin-producing ability. According to Agar-spot method, only 48 isolates out of 96, showed bacteriocinproducing ability with clear-zone production on plates against indicator organisms. With well-diffusion Assay, these numbers decreased to 20 isolates which produced clear zone. Then, these 20 isolates (strains) were subjected to rep-PCR for typing and 15 distinct rep-PCR profiles (patterns) were identified.
Polyphasic characterization of Enterococcus strains isolated from traditional Moghan cheese in Iran
Journal of Food Safety, 2019
Traditional Moghan cheese is made from unpasteurized milk in the rural areas and nomadic tribes of Moghan region in Iran. In this study, we used a simple and rapid method for isolation of acid resistant lactic acid bacteria from traditional Moghan cheese. The six distinct isolates differentiated based on RAPD‐PCR were identified as members of Enterococcus faecium, E. faecalis, and E.durans species using classical phenotypic and biochemical tests as well as molecular methods. Based on the antibiotic susceptibility, the isolates were classified as resistant, intermediate, and sensitive. Cell‐free culture supernatants of isolates showed different antagonistic activity against the growth of some spoilage and food‐borne pathogens at two natural and neutralized pH conditions. Considering their tolerance to acid and bile, antagonistic effects on some spoilage and food‐borne pathogens and susceptibility to vancomycin, E. faecium strain ABRIINW.M (isolate IE2) and E. faecium strain ABRIINW.N...
Partial characterisation of enterocin KP produced by Enterococcus faecalis KP, a cheese isolate
Enterococcus faecalis KP, a bacteriocin-producing strain, was identified using 16S rRNA gene sequence homology (99%). Enterocin KP from E. faecalis KP was sensitive to papain and ß-mercap-toethanol, but resistant to trypsin, pepsin, lipase, catalase, a-amylase, organic solvents, detergents, EDTA and heat treatment (90°C ⁄ 30 min). It was active at a wide pH range (2.0–8.0) and produced at maximum level in de Mann Rogosa Sharpe broth at 32°C with an inoculum amount of 0.1–1.0% and an initial pH of 5.5–7.5. It was active against some Gram-positive bacteria, including Listeria monocytogenes. It showed bactericidal activity against L. monocytogenes and its molecular weight was approximately 5.8 kDa.
Antimicrobial Resistance of Enterococcus sp. Isolated from Sheep and Goat Cheeses
Foods
This study aimed to calculate the proportion of antibiotic resistance profiles of Enterococcus faecium, E. faecalis, and E. durans isolated from traditional sheep and goat cheeses obtained from a selected border area of Slovakia with Hungary (region Slanské vrchy). A total of 110 Enterococcus sp. were isolated from cheese samples, of which 52 strains (E. faecium (12), E. faecalis (28), E. durans (12)) were represented. After isolation and identification by polymerase chain reaction and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry, the enterococci (E. faecium, E. faecalis, and E. durans) were submitted to susceptibility tests against nine antimicrobial agents. In general, strains of E. faecalis were more resistant than E. durans and E. faecium. A high percentage of resistance was noted in E. faecalis to rifampicin (100%), vancomycin (85.7%), teicoplanin (71.4%), erythromycin (71.4%), minocycline (57.1%), nitrofurantoin (57.1%), ciprofloxacin (14.3%), a...
Food Control, 2013
The aims of this study were to characterize bacteriocin activity, some functional and probiotic properties, and to evaluate the safety of Enterococcus faecium AQ71 isolated from Azerbaijani Motal cheese. The studied strain inhibited the growth of selected tested LAB, Listeria monocytogenes and Bacillus cereus strains. PCR amplification with specific primers indicated that E. faecium AQ71 carry genes encoding enterocins P, L50A, L50B and A. Bacteriocin(s) produced by the studied strain was/were heat stable and active in a broad pH range. Triton X-20, Triton X-80, Triton X-100, b-mercaptoethanol, Na-EDTA, SDS and NaCl did not affect the antimicrobial activity of the strain. The cell free supernatants of the strain caused the lysis of cells of Lactobacillus brevis F145 and inhibited the growth of L. monocytogenes. E. faecium AQ71 was negative for the tested virulence factors and did not present multi-resistance to antibiotics. The strain was resistant to physiological concentrations of bile salts and showed good auto-aggregation ability as well as co-aggregation ability with L. monocytogenes. E. faecium AQ71 exhibited good esterase, esterase lipase, acid phosphatase and aminopeptidase activities.
European Food Research and Technology, 2012
Strong bacteriocins, or bacteriocins with a wide range of activity against pathogens and spoilage microorganisms, are actively sought for use as natural food preservatives. This work reports the inhibitory activity of 96 enterococcal isolates from two Iranian, raw milk cheeses against Wve indicator organisms (including Listeria innocua). Forty-eight isolates inhibited at least one indicator in spot agar assays. Of these, 20 isolates corresponding to 15 diVerent strains were shown to produce bacteriocinlike substances in liquid cultures. PCR analysis revealed the genes coding for enterocins (enterococcal bacteriocins) A, B, P or X, or their combinations, in all but one of these 15 strains. In addition, the gene coding for enterocin 31 was detected in two strains. No ampliWcation was obtained in one strain when using speciWc primers for all 13 bacteriocin genes sought. Three diVerent enterocin genes were identi-Wed in most strains and four in one strain. Although the concomitant production of bacteriocins is still to be veri-Wed, producers of multiple enterocins could be of great technological potential as protective cultures in the cheese industry.