Süt kaynaklı Staphylococcus aureus suşları gelişimi üzerine peynirdeki nisinin etkisi

Abstract

The use of bacteriocins in protecting the foods has significantly increased in recent years. Nisin is an important bacteriocin and is a food preservative additive safely used in food industry. In the present study, it was aimed to investigate the effect of nisin, which is an alternative to the synthetic additives, on the growth of milk-derived Staphylococcus aureus strains in the cheese. For this purpose, 100 different milk specimens were obtained, transferred using cold chain (at 0-4°C), and inoculated to Baird-Parker agar. At the end of inoculation process, 37 suspicious colonies were selected and coagulase-positive Staphylococcus aureus was detected. The strains obtained were passaged to the pre-enriched agars and the intensities of the strains were determined according to McFarland. Besides these strains, the coagulase-positive Staphylococcus aureus strains obtained from Etlik Veterinary Microbiology Institute were inoculated into each specimen at 104 CFU mL-1 concentration. The cheese production was made using milks containing the strains, which were isolated from the milk, and the standard strains at different concentrations. The specimens obtained from cheeses produced from milk containing using standard strains were divided into groups K, A, B, and C containing 0, 100, 200, and 400 IU mL-1 nisin, respectively. Similarly, the specimens obtained from cheeses produced from milks containing milk-derived strains were divided into groups K1, A1, B1, and C1 containing 0, 100, 200, and 400 IU mL-1 nisin, respectively. The procedures were triplicated. Staphylococcus aureus counting on the cheese specimens were performed on 1st, 6th, 12th, and 24th hours from curd to ball and on 5th, 10th, 20th, 30th, and 40th days of storage at +4°C. In conclusion, it was observed that the nisin inhibited the growth of all the Staphylococcus aureus strains. However, it was also determined that the inhibition of milk-derived Staphylococcus aureus strains were higher than the inhibition of standard strains.