The distribution of aflatoxin M(1) (AFM(1)) has been studied between curd, whey, cheese and pickle samples of Turkish white pickled cheese produced according to traditional techniques and its stability studied during the ripening period. Cheeses were produced in three cheese-making trials using raw milk that was artificially contaminated with AFM(1) at the levels of 50, 250 and 750 ng/l and allowed to ripen for three months. AFM(1) determinations were carried out at intervals by LC with fluorescence detection after immunoaffinity column clean-up. During the syneresis of the cheese a proportionately high concentration of AFM(1) remained in curd and for each trial the level was 3.6, 3.8 and 4.0 times higher than levels in milk. At the end of the ripening, the distribution of AFM(1) for cheese/whey + brine samples was 0.9, 1.0 and 1.3 for first, second and third spiking respectively indicating that nearly half of the AFM(1) remained in cheese. It has been found that only 2-4% of the initial spiking of AFM(1) transferred into the brine solution. During the ripening period AFM(1) levels remained constant suggesting that AFM(1) was quite stable during manufacturing and ripening.

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In the present study, a total of 512 food samples composed of raw milk, dairy products, meat/meat products, chicken meat, seafood and raw vegetables were analyzed for the presence of Listeria monocytogenes. The results of the standard identification methods showed that 20 (3.9%) of the analyzed samples were found to harbor this pathogen. Further, 8.4% (13/155) of chicken meats, 0.9% (1/105) of meat/meat products and 13.6% (6/44) of fresh vegetables were contaminated with L. monocytogenes. Interestingly, only 18 of these isolates gave expected band size when they were subjected to molecular confirmation by polymerase chain reaction (PCR). Multiplex PCR serotyping of the strains revealed that 66.6% (12/18) of which belonged to serotype 1/2a (or 3a), 5.6% (1/18) to serotype 1/2b (or 3b, 7), 5.6% (1/18) to serotype 1/2c (or 3c) and 11.1% (2/18) to serotype 4b (or 4d, 4e). Two strains could not be serotyped by multiplex PCR. The strains were also evaluated by disk diffusion assay for their susceptibility to 15 commonly used antimicrobials. Antimicrobial resistance was most frequently observed for clindamycin (94.4%), followed by streptomycin and kanamycin (88.9%); penicillin (72.2%), tetracycline and gentamicin (66.7%); quinopristin/dalfopristin and erythromycin (61.1). Interestingly, 13 strains were resistant to more than five antibiotics. All strains were susceptible to linezolid, teicoplanin and vancomycin. Practical Applications Listeria monocytogenes is one of the most important foodborne pathogens responsible for several outbreaks and cases of listeriosis in human. This study focused on the prevalence of L. monocytogenes in different raw and ready‐to‐eat foodstuffs, and serotype distribution among the isolates. Antibiotic resistance profiles of the isolates were also reported. Information and relief provided to consumers could help elaborate public health and food safety.

The autolysis of lactic acid bacteria plays a major role during cheese ripening. The aim of this study was to evaluate the autolytic properties and peptidoglycan hydrolase content of dairy leuconostocs. Autolysis of 59 strains of dairy Leuconostoc was examined under starvation conditions in potassium phosphate buffer. The ability of dairy leuconostocs to lyse is strain dependant and not related to the species. The peptidoglycan hydrolase profile of Leuc. mesenteroides subsp. mesenteroides 10L was analysed by renaturing gel electrophoresis. Two major activity bands migrating at 41 and 52 kDa were observed. According to the specificity analysis, strain 10L seems to contain a glycosidase and an N‐acetyl‐muramyl‐l‐alanine amidase, or an endopeptidase. The peptidoglycan hydrolase profiles of various Leuconostoc species were also compared. Several peptidoglycan hydrolase activities could be detected in the different Leuconostoc species. Further characterization of the peptidoglycan hydrolases will help to control autolysis of leuconostocs in cheese.