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Öğe Characterization of SE-P3, P16, P37, and P47 bacteriophages infecting Salmonella Enteritidis(Wiley, 2019) Yildirim, Zeliha; Sakin, Tuba; Akcelik, Mustafa; Akcelik, NesifeThe aim of this study was to identify and characterize the SE-P3, P16, P37, and P47 phages infecting Salmonella Enteritidis. Transmission electron microscopy analysis showed that the SE phages belonged to the Myoviridae or Siphoviridae family and had plaque sizes between 0.622 +/- 0.027 and 1.630 +/- 0.036mm in diameter. sefC, pefA, spvC, sopE, and gipA virulent gene regions were absent in their genome and their calculated genome sizes were between 35.9 and 37.8 kbp. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that the protein profiles of each phage were different. The SE phages had a short latent period (10-20 min), large burst size (76-356 PFU/cell), and a short burst time (25-35 min). The multiplicity of infection values and mutant frequency of the phages were 0.01-0.0001 and 10(-7), respectively. They were very infective against their host bacteria when applied at 20 degrees C, 30 degrees C, or 37 degrees C and adsorbed to their host cells by 96.20-97.65% in the first 5 min of incubation, and also Ca2+ ions did not have a significant effect on their adsorption. The SE phages were resistant to wide pH ranges and high temperatures. These results indicate that the SE phages are good candidates as therapeutic and biocontrol agents against foodborne pathogenic S. Enteritidis.Öğe Identification and characterization of lytic bacteriophages specific to foodborne pathogenicEscherichia coliO157:H7(Sage Publications Ltd, 2021) Yildirim, Zeliha; Sakin, Tuba; Akcelik, Mustafa; Akcelik, NefiseThe objective of this study was to identify and characterize five different lytic bacteriophages specific toEscherichia coliO157:H7. vB_EcoM-P12, vB_EcoM-P13, vB_EcoM-P23, and vB_EcoM-P34 phages belonged to the Myoviridae family and vB_EcoS-P24 phage was in the Siphoviridae family. Their plaque sizes changed between 0.48 +/- 0.03 and 0.90 +/- 0.03 mm in diameter.stx1andstx2virulent gene regions were absent in the genome of five Eco-phages and their genome size was 33 kbp. The protein band profiles of the five phages were found to be different from each other. Their latent period, burst size, and burst time changed between 10-15 min, 72-144 PFU/cell and 20-35 min, respectively. Multiplicity of infection values and mutant frequency of the phages were among 0.1-0.001 and 1.14 x 10(-7)-3.69 x 10(-8), respectively. The phages had strong lytic activity against their host bacteria (E. coliNCTC 12900, ATCC 43888, and ATCC 35150) at 5-37 celcius and adsorbed to their host cells by 92.7-97.5% in the first five minutes of incubation. These phages are thought to be good candidates as therapeutic and biocontrol agents againstE. coliO157:H7 in the veterinary science and food industry due to short latent period, high burst size, rapid development in host cells, high lytic activity, high adsorption rate, stability over a wide pH range and high temperature, and absence ofstx1andstx2genes.Öğe Inhibitory Effect of Lactococcin BZ Against Listeria innocua and Indigenous Microbiota of Fresh Beef(FACULTY FOOD TECHNOLOGY BIOTECHNOLOGY, 2016) Yildirim, Zeliha; Yerlikaya, Sabire; Oncul, Nilgun; Sakin, TubaIn this study, the effect of lactococcin BZ on microbiological quality of fresh beef is investigated. For this purpose, the meat samples were treated with various amounts of lactococcin BZ (200-2500 AU/mL), a bacteriocin produced by Lactococcus lactis spp. lactis BZ, and kept at 4-5 degrees C for 12 days. During storage, the microbiological properties of the meat samples with or without lactococcin BZ were determined. Inhibitory effect of lactococcin BZ depended on its amount. The higher the amount of lactococcin BZ, the higher the inhibitory activity. Treatment with lactococcin BZ at the level of 2500 AU/mL resulted in 4.87, 3.50 and 3.94 log cycle decrease in the counts of mesophilic, psychrotrophic and lactic acid bacteria, respectively, and 1.90.10(4) and 1.04.10(2) CFU/g reduction in conform and faecal conform bacteria, respectively, at the end of storage as compared to their initial numbers in the control sample. However, the counts of these bacteria in control samples increased during storage. Also, lactococcin BZ at 1600 AU/mL showed very strong antilisterial effect against Listeria innocua in fresh meat and reduced the cell numbers from 6.04 log CFU/g to undetectable level on the 6th day of storage. In conclusion, lactococcin BZ has a potential use as a biopreservation agent to improve safety and shelf life of raw beef.Öğe Isolation of Anti-Escherichia coli O157:H7 Bacteriophages and Determination of Their Host Ranges(2018) Yıldırım, Zeliha; Sakin, Tuba; Çoban, FatmaThe aim of this study was to isolate, purify and determine host ranges of bacteriophagesinfecting Escherichia coli O157:H7 from different environment such as river/streamwater, sewage, raw food, animal troughs, wastewaters of food processing plants,slaughterhouse and fish farms. For screening of E. coli O157:H7 bacteriophages, 92samples were used. It was found that in respect to anti-E. coli O157:H7 bacteriophages,food processing wastewaters, sewage and slaughterhouse wastewaters are the richestsources, and streams, troughs and fisheries wastewater are rich in the middle, and rawfoods were the poorest source. A total of 37 phages were isolated and purified. Thephages counts of the purified samples were changed among 30×103 - 34×108 PFU/mL.The isolated phages were generally infective against E. coli O157:H7 and E. coli strainsand 81.08% of the phages (30 out of 37) formed clear plaques and were capable to lyse atleast 1 out of 5 E. coli O157:H7 strains. In addition to E. coli, some phages were capableto infect some Salmonella enterica serovars. This results show that inhibitor spectra ofthe phages were wide.Öğe Taze sığır etinde listeria monocytogenes ve Escherichia coli O157: H7'ye karşı Lactococcus lactis spp. lactis BZ' nin biyokoruyucu kültür olarak kullanılması(Niğde Üniversitesi / Fen Bilimleri Enstitüsü, 2014) Sakin, Tuba; Yıldırım, ZelihaBu çalışma bakteriyosin üreten Lactococcus lactis spp. lactis BZ’nin taze sığır etinin mikrobiyolojik kalitesine etkisi ile ete inoküle edilen Listeria monocytogenes ve Escherichia coli O157:H7’e kar?ı antimikrobiyal etkisini ortaya koymak amacıyla gerçekleştirilmiştir. Bu amaçla, et örneklerinin yüzeyi yaklaşık 107-108 kob/g düzeyinde Lactococcus lactis spp. lactis BZ ile muamele edildikten sonra buzdolabı sıcaklığında (4-6°C) 12 gün süreyle depolanmıştır. Depolamanın belirli periyotlarında alınan et örneklerinde toplam psikrotrof aerobik bakteri ve toplam koliform bakteri sayımları yapılmıştır. Ayrıca et örneklerinin pH ile L*, a* ve b* değerleri de belirlenmiştir. L. lactis spp. lactis BZ’nin kontaminasyon esnasında, kontaminasyondan önce veya sonra L. monocytogenes (yakla?ık 104 kob/g) ve E. coli O157:H7 (yakla?ık 104 kob/g)’ye karşı antibakteriyal aktivitesi de belirlenmiştir. Bu amaçla L. lactis spp. lactis BZ, patojen bakteriler ile aynı anda veya patojen bakterilerin ilavesinden 24 saat önce veya sonra et örneklerine inokule edilmiştir. L. lactis spp. lactis BZ taze sığır etine 8,01 log kob/g düzeyinde uygulandığında toplam psikrotrof aerobik bakteri ve toplam koliform bakterilerin gelişimini yavaşlatarak taze sığır etinin mikrobiyolojik kalitesini iyileştirdiği belirlenmiştir. L. lactis spp. lactis BZ içeren ve içermeyen bütün örneklerin pH değerlerinin depolama süresince arttığı, renk (L*, a* ve b*) değerlerinin ise azaldığı saptanmıştır. Ancak, L. lactis spp. lactis BZ içeren et örneklerinde pH değerlerinin kontrol örneğine göre daha yavaş bir şekilde arttığı, renk (L*, a* ve b*) değerlerinin ise daha yavaş bir şekilde azaldığı gözlenmiştir. L. lactis spp. lactis BZ, L. monocytogenes veya E. coli O157:H7’nin kontaminasyonu esnasında, kontaminasyonundan 24 saat önce veya sonra ete inokule edildiğinde patojen bakterilerin gelişimini önlediği belirlenmiştir. Buzdolabında muhafazanın 3. gününden itibaren L. lactis spp. lactis BZ ile muamele edilen bütün et örneklerinde L.monocytogenes sayısının sayılamayacak düzeyin altına düştüğü gözlenmiştir. E. coli O157:H7 sayısı ise kontaminasyondan 24 saat önce L. lactis spp. lactis BZ ile muamele edilen örnekte depolamanın 3’üncü, patojen bakteri ile aynı anda veya patojen bakteri ilavesinden 24 saat sonra L. lactis spp. lactis BZ uygulanan et örneklerinde depolamanın 5’inci gününden itibaren sayılamayacak düzeye indiği saptanmıştır. Sonuç olarak, bakteriyosinojenik L. lactis spp. lactis BZ koruyucu kültür olarak kullanıldığında taze sığır etinin raf ömrünü, mikrobiyolojik kalitesi ve güvenliğini iyileştirdiği belirlenmiştir. Ayrıca, L. monocytogenes veya E. coli O157:H7’nin kontaminasyonu esnasında, kontaminasyonlarından 24 saat önce veya sonra ete uygulandığında patojen bakterilere karşı kuvvetli antibakteriyal aktivite gösterdiği de saptanmıştır.
