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Öğe Application of lactococcin BZ and enterocin KP against Listeria monocytogenes in milk as biopreservation agents(Akademiai Kiado Rt., 2016) Yıldırım, Zeliha; Öncül, Nilgün; Yıldırım, Metin; Karabıyıklı, ŞenizThis study was performed to evaluate the effect of lactococcin BZ and enterocin KP against Listeria monocytogenes ATCC 7644 in skim (0.1%), half (1.5%), and full fat (3.0%) UHT milks. The milk samples were inoculated with L. monocytogenes at the level of approximately 2.60, 4.76, and 6.45 log CFU ml(-1), and then treated with various concentrations (400, 800, 1600, or 2500 AU ml(-1)) of lactococcin BZ, enterocin KP, or their combination (1: 1). Lactococcin BZ at 400-2500 AU ml(-1) level displayed strong antilisterial activity, and decreased the viable cell numbers of L. monocytogenes to an undetectable level in all types of milk samples during the entire storage periods at 4 degrees C or 20 degrees C. Enterocin KP also had a high antilisterial effect, but it decreased as both the fat content of milk and inoculation amount of L. monocytogenes increased.Öğe GROWTH ABILITY OF BACTERIOCINOGENIC STRAINS IN MILK ANDTHEIR BACTERIOCIN ACTIVITY AGAINST CHEESE STARTER CULTURES(2020) Öncül, Nilgün; Yıldırım, ZelihaIn this study, the growing ability of Lactococcus lactis ssp. lactis BZ and Enterococcus faecalis KP in different fat content milk at 30°C for 48 hours and the efficiency of their bacteriocins, lactococcin BZ and enterocin KP, against three types of cheese starter (Choozit MA 11LYO 50, Choozit MA 19LYO 50 and DI-Prox M265) in full fat milk were determined. The growth and bacteriocin production abilities of L. lactis ssp. lactis BZ and E. faecalis KP in milk were examined for 48 hours at 30°C. As a result of the study, it was determined that both bacteria grew better in milk with low fat content and produced more bacteriocin. It was found that lactococcin BZ (1600 AU/mL) and enterocin KP (1600 AU/mL) had an inhibitory effect against three different cheese starter cultures analyzed when used separately or in combination.Öğe Investigation of the Microbiological Quality of Tokat Bez Sucuk(2020) Kaval, Nesrin; Öncül, Nilgün; Yıldırım, ZelihaIn this study, the microbiological quality of traditionally produced Bez Sucuk in Tokat and its vicinitywas investigated. For this purpose, 30 Bez Sucuk samples obtained from butchers, producers of BezSucuk, were analyzed for total count of mesophilic aerobic bacteria, lactic acid bacteria, yeastsmoulds, total coliform, fecal coliform, Staphylococcus aureus, Bacillus cereus, and Cl. perfringens.Also, the presence of Escherichia coli O157:H7, Listeria monocytogenes and Salmonella spp. wereinvestigated in all samples. pH and water activity of the samples were determined. As the result ofthe analysis, the counts of the microbiological parameters investigated were found as follows: totalmesophilic aerobic bacteria 3.5×106-4.23×109 CFU/g, lactic acid bacteria 5.55×105-2.45×109CFU/g,yeasts and moulds 2.50×103-6.90×109 CFU/g, total coliform <0.03-2.4×106 CFU/g, fecal coliform<0.03-0.23×105 CFU/g, Staphylococcus aureus 3.55×103-1.84×107 CFU/g, Bacillus cereus1.16×102-6.65×103 CFU/g, and Clostridium perfringens 2.25×103-2.86×105 CFU/g. Based onconfirmation and identification tests, E. coli biyotype 1 was found in 10 samples (33.33%), E. colibiyotype 2 in 2 samples (6.67%), E. coli O157:H7 in 16 samples (53.33%), Listeria monocytogenesin 5 samples (16.67%), and Salmonella spp. in 13 samples (43.33%). pH and the water activity valuesof the samples were between 4.69-6.94 and 0.774-0.979, respectively. In conclusion, Bez Sucuksexamined may threaten human health due to very high microbial counts and presence of many foodborne pathogens.Öğe Laktokoksin BZ ve Enterosin KP'nin Yoğurt Kültürlerinin Aktivitesi Üzerine Etkisi(2015) Öncül, Nilgün; Yıldırım, Zeliha; Yıldırım, MetinBu çalışmada, Lactococcus lactis spp. lactis BZ ve Enterococcus faecalis KPden elde edilen laktokoksin BZ ve enterosin KP (1600 AU/mL) bakteriyosinlerinin üç farklı yoğurt kültürlerine (Y1, Y2: CHR Hansen, Danimarka, Y3: Sacco, İtalya) karşı inhibitör etkileri belirlenmiştir. İnkübasyon süresince (42°Cde 24 saat) belirli aralıklarla alınan örneklerde laktik asit bakteri sayısı ve pH değerleri incelenmiştir. Laktokoksin BZnin test edilen 3 yoğurt kültüründen sadece birine, enterosin KPnin ise iki yoğurt kültürüne karşı bakterisidal etkiye sahip olduğu görülmüştür. Laktokoksin BZ ve enterosin KP 1:1 oranında karışım halinde kullanıldığında da iki yoğurt kültürüne karşı bakterisidal aktivite gösterdiği belirlenmiştir.Öğe Microbiological Quality of Raw Meat Sold in Tokat Province#(2019) Öncül, Nilgün; Yıldırım, ZelihaAccording to World Health Organization (WHO), an estimated 600 million people fall ill after eating contaminated food and 420 000 die every year. Although various foods can serve as sources of foodborne illness, meat has been at the forefront of societal concerns in recent years. Meat is source of some foodborne pathogens which have an important role on human health. In this study, it was aimed to examine the microbiological quality of raw bovine meat samples sold in Tokat province and to evaluate the results in the context of food safety. For this purpose, 18 raw meat samples purchased from butchers and markets were analyzed for total mesophilic aerobic bacteria, total psychrophilic aerobic bacteria,yeasts-molds,lacticacidbacteria, B.cereus,S.aureus,C. perfringens, total coliform, and fecal coliform. The presence of E. coli, E. coliO157:H7, L. monocytogenesand Salmonellaspp. were also investigated in these samples. The lowest and highest values determined for the parameters were as follows: total mesophilic aerobic bacteria 1.46×104-1.26×107CFU/g, total psychrotrofic aerobic bacteria 1.01×104-2.65×106CFU/g, yeasts-molds 3.00×103-1.70×104CFU/g, lactic acid bacteria 2.70×103-3.60×104CFU/g, B. cereus?102-7.20×104CFU/g, S. aureus2.60×103-2.57×105CFU/g, C. perfringens?102-9.20×103CFU/g, total coliform 3.80×101-2.90×104MPN/g, and fecal coliform <0.30-9.30×103MPN/g. Salmonellassp.,E. coliO157:H7, and L. monocytogenes were not detected in the meat samples.
