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    Genetic Differentiation of Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus Strains Isolated from Raw Milk Samples Collected from Different Regions of Turkey
    (Taylor & Francis Inc, 2015) Yilmaz, Remziye; Temiz, Ayhan; Acik, Leyla; Keskin, Ayten Celebi
    Yogurt is a fermented milk product produced by two homofermentative lactic acid bacteria, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. It is consumed throughout the world as a healthy, nutritional food. In this study, the strains of Lactobacillus and Streptococcus were isolated from raw milk samples collected from different local geographical regions of Turkey. One hundred and thirty isolates were characterized to genus level by classical morphological, physiological and biochemical tests. Twenty six of all isolates were identified as L. delbrueckii subsp. bulgaricus and 47 isolates were identified as S. thermophilus using API 50 CHL system. RAPD-PCR was used to explain molecular characterization and genetic differentiation of a total of 73 strains. The whole cell protein profiles of these strains were tested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In this study, all strains were identified by the RAPD-PCR technique to species or strain level. SDS-PAGE was also shown to be an effective method for molecular differentiation all of the strains. Phenotypic identification, RAPD-PCR and SDS-PAGE proved to be informative methods suitable to explain molecular characterization and genetic differentiation of L. delbrueckii subsp. bulgaricus and S. thermophilus strains isolated from raw milk. In the present study, we described an identification system by using RAPD-PCR and SDS-PAGE techniques and used this system for genetic differentiation of L. delbrueckii subsp. bulgaricus and S. thermophilus strains isolated from raw milk. It is believed that these two molecular techniques allow researchers to fill the significant gaps present in our understanding of these organisms by providing a comprehensive view potentially involved in industrially relevant phenotypes from different geographical origin.
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    Investigation of potential virulence genes and antibiotic resistance characteristics of Enterococcus faecalis isolates from human milk and colostrum samples
    (Tubitak Scientific & Technical Research Council Turkey, 2014) Togay, Sine Ozmen; Temiz, Ayhan; Celebi, Ayten; Acik, Leyla; Yalcin, Siddika Songul
    Enterococci may improve the typical taste and flavor of fermented foods through their proteolytic and lipolytic activities. However, some enterococcal strains are recognized as nosocomial pathogens, which have virulence genes and resistance to certain antibiotics. Enteroccocci are also found in human milk microflora. The aim of this study was to investigate the potential virulence genes and antibiotic resistance characteristics of Enterococcus faecalis isolates from human milk and colostrum samples. In total, 23 Enterococcus faecalis strains were identified from human milk and colostrum samples. Antibiotic-resistant E. faecalis isolates were determined using the disk diffusion method. Vancomycin resistance genes (vanA, vanB) and some virulence genes (agg(2), gelE, efaAfm, ccf, cpd, cad, cylM, cylB, etc.) were investigated using polymerase chain reaction (PCR). All strains were sensitive to ampicillin, penicillin G, chloramphenicol, and vancomycin. None of the E. faecalis isolates contained vanA, vanB, or efaAfm genes. The results of this study indicated that there were no harmful enterococci strains in human milk and colostrum samples in terms of tested virulence factors and antibiotic resistance. Therefore, the E. faecalis isolates from human milk may have the potential to be considered as a functional culture for the food industry.
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    Protein patterns and plasmid profiles of the bacterial strains isolated from a poultry slaughterhouse in Ankara, Turkey
    (Faculty Food Technology Biotechnology, 2005) Açık, Leyla; Temiz, Ayhan; Çelebi, Ayten; Arslan, Sevim; Yılmaz, Remziye
    A total of 65 identified isolates of coliform bacteria Salmonella, including Campylobacter and Staphylococcus isolated from different control points of a poultry slaughterhouse in Ankara, Turkey were characterized by morphological, biochemical and physiological tests including API 10 S system, and by plasmid profiles on agarose gel electrophoresis and whole-cell protein patterns on SDS-PAGE. Plasmids were detected in 53.8 % of the isolates. The molecular mass of the plasmids was within the range from 0.66 to 12.66 mDa. Electrophoretic banding patterns showed that whole cell protein profiles differed in several protein bands in Salmonella, Campylobacter and Staphylococcus species, but the differences were insufficient for reliable differentiation of bacteria species by SDS-PAGE method.
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    Virulence genes, antibiotic resistance and plasmid profiles of Enterococcus faecalis and Enterococcus faecium from naturally fermented Turkish foods
    (Wiley-Blackwell, 2010) Togay, S. Özmen; Keskin, A. Çelebi; Açık, Leyla; Temiz, Ayhan
    Aim: To determine the virulence genes, antibiotic resistance and plasmid profiles of 16 Enterococcus faecium and 68 Enterococcus faecalis strains isolated from various naturally fermented foods. Methods and Results: The presence of virulence genes (agg(2), gelE, cylM, cylB, cylA, espfs, espfm, efaAfs, efaAfm, cpd, cop, ccf, cad) and also the genes vanA and vanB were investigated by polymerase chain reaction (PCR). Antibiotic resistance of the isolates was determined by disc diffusion method. Most of the tested isolates were positive for virulence genes and resistant to some antibiotics. One of the Ent. faecalis strains isolated from a cheese sample carried the vanA gene and was intermediately resistant to vancomycin. The strains usually contained large plasmids, which might harbour acquired antibiotic resistance. Conclusion: The study showed that Ent. faecium and Ent. faecalis strains isolated from naturally fermented Turkish foods may be potential risk factors for consumer health in terms of virulence genes and acquired antibiotic resistance. Significance and Impact of the Study: The results indicate the importance of enterococcal contamination in terms of the safety of some fermented Turkish foods.