Zeliha Yildirim

Factors affecting the adsorption of buchnericin LB, a bacteriocin produced by Lactocobacillus buchneri

Summary Buchnericin-LB adsorbs to gram-positive but not to gram-negative bacteria. The tested gram-positive bacteria were species of Lactobacillus , Pediococcus , Leuconostoc , Enterococcus , Lactococcus , Listeria , Bacillus , Staphylococcus ; gram-negative bacteria belonged to the genera Salmonella , Escherichia , Yersinia and Pseudomonas . Buchnericin-LB adsorption depended on pH but not on time and temperature. Also some anions of salts and lipoteichoic acid reduced or inhibited its adsorption. Treatment of cells and cell walls of sensitive bacteria with detergents, organic solvents or enzymes did not affect subsequent binding of buchnericin-LB. Treatment with buchnericin-LB caused sensitive cells to lose high amounts of intracellular K + ions and UV-absorbing materials and became more permeable to o-nitrophenol-β-D-galactopyranoside. Buchnericin-LB (640-2560 AU/ml) decreased the colony forming units (99%) and absorbance values of Listeria monocytogenes and Bacillus cereus . These results indicate that the mode of action of buchnericin-LB is bactericidal and its lethal effect is very rapid.

Effects of season on vitamins A and E contents and colour of Turkish butter

Butter is a product that consists of roughly the same constituents asmilk, but their distribution is different. In buttermaking, the fat contentof the milk is concentrated approximately 20 times. Milk and butter aregood sources of the fat solublevitamins A, D and E.Vitamin A (retinol) is a primary alcohol derivative of a polymer con-sisting of four isoprene units. Vitamin A is present in cow’s milk as reti-nol, retinol esters and carotenes. The content of vitamin A dependsstrongly on the amount of carotenoids in the feed. The ratio of retinol tocarotene in cow’s milk varieswith breed [1–3].Vitamin E consists of a group of tocopherols. The most potent ofthese and the principal one in milk is alpha-tocopherol. This is a strongreductant and serves as an antioxidant protecting lipids from oxidation.It is stable to heat but may be partly destroyed by intensive illuminationin the presence of O

Isolation of Anti-Escherichia coli O157:H7 Bacteriophages and Determination of Their Host Ranges

Received 04 May 2018 Accepted 12 July 2018 The aim of this study was to isolate, purify and determine host ranges of bacteriophages infecting Escherichia coli O157:H7 from different environment such as river/stream water, sewage, raw food, animal troughs, wastewaters of food processing plants, slaughterhouse and fish farms. For screening of E. coli O157:H7 bacteriophages, 92 samples were used. It was found that in respect to anti-E. coli O157:H7 bacteriophages, food processing wastewaters, sewage and slaughterhouse wastewaters are the richest sources, and streams, troughs and fisheries wastewater are rich in the middle, and raw foods were the poorest source. A total of 37 phages were isolated and purified. The phages counts of the purified samples were changed among 30×10 34×10 PFU/mL. The isolated phages were generally infective against E. coli O157:H7 and E. coli strains and 81.08% of the phages (30 out of 37) formed clear plaques and were capable to lyse at least 1 out of 5 E. coli O157:H7 strains. In addition to E. coli, some phages were capable to infect some Salmonella enterica serovars. This results show that inhibitor spectra of the phages were wide.

Isolation of lytic bacteriophages infecting Salmonella Typhimurium and Salmonella Enteritidis

The objectives of this study were to isolate, purify and determine host range of lytic bacteriophages infecting foodborne the pathogen Salmonella Typhimurium and S. Enteritidis. River/stream water, sewage, raw foods, wastewater from food processing plants, slaughterhouse and fish farms and water from troughs were used for the screening of bacteriophages. The richest sources in terms of phages infecting S. Typhimurium and Enteritidis were found to be sewage, wastewaters of slaughterhouse, food processing and fisheries and streams. A total of 33 S. Typhimurium and 56 S. Enteritidis phages were isolated and purified from the samples. It was demostrated that host ranges of the isolated phages were quite wide. The numbers of bacteria types inhibited by S. Typhimurium or Enteritidis phages were changed among 1-15 and 1-19, respectively. It was found that 75.8% (25 out of 33) and 83.93% (47 out of 56) of isolated S. Typhimurium or Enteritidis phages formed clear plaques and were capable of lysing at least six or two Salmonella serovars. Beside Salmonella serovars, some S. Typhimurium (15 out of 33, 45.5%) and S. Enteritidis phages (5 out of 56, 8.93%) were also infective against E. coli strains. The host ranges of S. Typhimurium phages were wider than those of S. Enteritidis.

Determination of Some Physicochemical and Microbiological Properties of Rosehip Marmalades

In this study, some physicochemical and microbiological properties and antioxidant capacity of 30 rosehip marmalades produced in Tokat province by industrial or regional methods were determined. pH, water activity, viscosity, total dry content, total soluble solids, total ash, total sugar content, total ascorbic acid content and Hunter values (L*, a* and b*) were carried out to determine the physicochemical properties of samples and the means were 4.12, 0.881, 2501.6 cP, 56.12%, 56.86, 0.935%, 50.24 g/L, 173.43 mg/100g, 30.89, 10.90 and 15.11, respectively. The count of S. aureus, total and fecal coliform was not detected in any samples. The total phenolic content and TEAC were performed to investigate antioxidant capacity and the average values were 921.62 mg GAE/100 g and 66.93 µmol trolox/g.

Yöresel Peynirden Antimikrobiyal Aktiviteye Sahip Laktik Asit Bakterisinin İzolasyonu ve Tanısı

Bu calismada yoresel bir peynirden antimikrobiyal aktiviteye sahip bir bakteri izole edilmis ve genel mikrobiyolojik analizler, karbonhidrat fermantasyon ve yag asidi profili testleri kullanilarak karakterize edilmis ve tanimlanmistir. Izole edilen bakterinin Gram pozitif, kok seklinde, hareketsiz, endospor, katalaz, hemoliz, jelatinaz, indol ve Voges Proskauer negatif, % 3,0-6,5 NaCl konsantrasyonunda, pH 4,5-9,6 ve 10-45oC’de gelisebildigi tespit edilmistir. Yapilan karbonhidrat fermantasyonu ile yag asidi profili testleri sonucunda bakterinin Enterococcus faecalis oldugu belirlenmistir. Bu bakteri tarafindan uretilen antimikrobiyal maddenin Lactobacillus plantarum, Enterococcus faecalis, Enterococcus faecium ve Listeria monocytogenes’a karsi inhibitor aktiviteye sahip oldugu, ancak Escherichia coli, Staphylococcus aureus ve Bacillus cereus’a karsi etkili olmadigi gozlenmistir. Antimikrobiyal aktivitenin asitlik ve hidrojen peroksitten kaynaklanmadigi belirlenmistir. Papainle muamele sonucu aktivitesini kaybetmesi antimikrobiyal bilesigin protein tabiatinda oldugunu ortaya koymustur.