Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Identification of Staphylococcus Aureus Cheese Isolates With Respect To Virulence Properties, Genetic Relatedness and Antibiotic Resistance Profiles(Özkan Özden, 2019) Kadiroğlu, Pınar; Korel, Figen; Ceylan, ÇağatayThe problems on identification of Staphylococcus aureus isolates from cheese samples wereinvestigated by phenotypic and genotypic tests in this study. Among 207 Staphylococcus spp.isolated from 31 cheese samples, 23 isolates that were Gram positive, catalase and slide coagulasepositive, with 1 isolate that was latex agglutination test negative showed different phenotypicproperties. Polymerase chain reaction (PCR) and quantitative PCR (qPCR) analyses showed thatDNase test and target genes (nuc, coa) regarded as gold standard regions for S. aureus were notfound to be unique for identification of S. aureus. The toxin genes (SEA-SEE) were not detected byPCR. Antibiotic resistance profiles of S. aureus isolates demonstrated that two isolates were resistantto penicillin G. This study showed that the unique phenotypic and genotypic test was not adequatefor identification of S. aureus isolates. There was no correlation between the presence of the nucgene and toxin genes. The presence of nuc gene which was used for detection of S. aureus was alsofound to be present in other Staphylococcus isolates. As a conclusion, the results revealed thatbiochemical tests could lead to false positive results for identification of S. aureus. The presence ofnuc gene is not correlated with the presence of toxin genes.Article Citation - WoS: 5Citation - Scopus: 5Microbiological Quality of Artisanal Sepet Cheese(John Wiley and Sons Inc., 2014) Ercan, Duygu; Korel, Figen; Orşahin, HandeMicrobial diversity in milk and in cheese itself affects the biochemical and sensory characteristics of artisanal cheeses. In this study, the microflora of Sepet cheese, which is a traditional artisanal cheese in Turkey, was investigated. Average lactococci, lactobacilli, enterococci, yeast, mould, coliform, psychrotrophic and total aerobic bacteria, presumptive Staphylococcus aureus counts were; 7.31 ± 1.08, 7.19 ± 1.02, 6.84 ± 0.92, 3.19 ± 1.40, 0.84 ± 0.89, 2.18 ± 1.81, 4.92 ± 1.15, 7.53 ± 1.13 and 1.25 ± 1.70 log cfu/g, respectively. Staphylococci, coliform and mould counts were less than 1.00 log cfu/g at the end of ripening, which was at around 6-8 °C for 3 months. According to phenotypic and genotypic identifications, isolates were closely related to Lactobacillus plantarum, Weisella confusa, Weisella paramesenteroides, Pediococcus pentasaceous, Enterococcus casseliflavus, Enterococcus durans and Enterococcus faceium. This study provides baseline data on the microflora of traditional artisanal Sepet cheese, which is a prerequisite for a successful scale up to industrial production.Article Citation - WoS: 40Citation - Scopus: 38Homofermentative Lactic Acid Bacteria of a Traditional Cheese, Comlek Peyniri From Cappadocia Region(Cambridge University Press, 2005) Bulut, Çisem; Güneş, Hatice; Okuklu, Burcu; Harsa, Hayriye Şebnem; Kılıç, Sevda; Çoban, Hatice S.; Yenidünya, Ali FazılComlek peyniri is a typical artisanal cheese in Central Anatolia. This type of cheese was made by using the indigenous lactic acid bacteria (LAB) flora of cow or ewes' milk. Majority of the samples were taken from fresh cheese because the aim was to isolate homofermentative LAB. Initially 661 microbial isolates were obtained from 17 cheese samples. Only 107 were found to be homofermentative LAB. These isolates were selected and identified by using both phenotypic and molecular methods. Phenotypic identification included curd formation from skim milk, catalase test, Gram staining and light microscopy, growth at different temperatures and salt concentrations, arginine hydrolysis, gas production from glucose, and carbohydrate fermentation. Molecular identification was based on the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the 16S rRNA gene-ITS (internally transcribed spacer) region. By combining the phenotypic and molecular identification results, isolates belonging to each of the following genera were determined at species or subspecies level: 54 Lactococcus lactis subsp. lactis, 21 Enterococcus faecium, 3 Ec. faecalis, 2 Ec. durans, 10 Ec. sp., 15 Lactobacillus paracasei subsp. paracasei, and 2 Lb. casei strains. Technological characterisation was also performed by culturing each of the strains in UHT skim milk, and by monitoring pH change and lactic acid production at certain time intervals through the 24 h incubation. Results of the technological characterisation indicated that 33% of the isolates (35 strains) were capable of lowering the pH of UHT milk below 5.3 after 6 h incubation at 30°C. Thirty four of these strains were Lc. lactis subsp. lactis, and only one was an Ec. faecium strain.