Lizozim ve Nisinin Gıda Kaynaklı Staphylococcus aureus Suşlarında Gelişim ve Biyofilm Oluşumu Üzerine Etkileri

OZET Staphylococcus aureus gidalarda gelisebilen ve urettigi toksinlerle gida zehirlenmesine yol acan en onemli patojen bakterilerdendir. Bu calismada, besin maddelerinde siklikla biyokoruyucu olarak kullanilan lizozim ve nisinin, degisik gidalardan izole edilen 14 adet S. aureus susunun gelisme ve biyofilm olusturmasi uzerindeki etkileri kantitatif mikroplaka yontemi ile arastirilmistir. Elde edilen veriler dogrultusunda 1, 2, 3, 4 ve 5 mg/ml konsantrasyonlardaki lizozimin, bakteri gelismesini engelleme yonunde hicbir etkisinin olmadigi ve tum suslarin lizozime karsi direncli olduklari tespit edilmistir. Diger yandan, 12,5 I¼g/ml konsantrasyonda nisinin bazi suslarda % 100 inhibisyon gosterdigi saptanmis, sadece bir susta ise ( S. aureus SE-22C) 37,5 I¼g/ml konsantrasyonda uzun inkubasyon sonrasinda gelisme gorulmustur. Biyofilm testleri sonucunda, lizozimin artan konsantrasyonlarinin dort susta biyofilm yapimini aktive ettigi, bir susta ise lizozim icermeyen besiyerine gore once azalttigi, artan lizozim konsantrasyonlarinda ise biyofilm olusumunu arttirdigi tespit edilmistir. Diger yandan lizozimin artan konsantrasyonlarinin iki susta biyofilm olusumunu azalttigi gorulmustur. Nisinin artan konsantrasyonlarinin dort susta bakterilerin biyofilm olusumunu azalttigi, diger suslarda ise bir degisiklige yol acmadigi bulunmustur. Calismamiz neticesinde lizozimin S. aureus suslarina karsi etkisiz bir biyokoruyucu oldugu, fakat biyofilm yapimini aktive edebildigi; buna karsin nisinin yuksek konsantrasyonlarda bakteri gelismesi uzerine inhibisyon etkisinin oldugu, ancak nisine direncli S. aureus suslarinin bulunabilecegi sonucuna varilmistir. Anahtar Kelimeler: Staphylococcus aureus , lizozim, nisin, biyofilm, gida ABSTRACT EFFECTS OF LYSOZYME AND NISIN ON GROWTH AND BIOFILM FORMATION OF FOODBORNE STAPHYLOCOCCUS AUREUS STRAINS Staphylococcus aureus is one of the most important pathogenic bacteria in food producing toxins and causing food poisoning. In this study, the effects of biopreservatives lysozyme and nisin on growth and biofilm formation of S. aureus strains (n=14) isolated from different foods were examined by quantitative microplate method. On the basis of obtained data, 1, 2, 3, 4, and 5 mg/ml of lysozyme concentrations did not inhibit the growth of strains and all strains were determined as resistant to lysozyme. On the other hand, nisin at 12,5 mg/ml concentration showed 100% inhibition on most of the strains, except S. aureus SE-22C strain at 37,5 mg nisin/ml concentration, the growth of strain was obtained after a long incubation time. As a result of biofilm tests, in four strains increasing concentrations of lysozyme were found to activate biofilm formation. In SE-22C strain, with compared to medium without lysozyme, firstly biofilm formation was decreased then with increasing lysozyme concentrations the increased biofilm formation was obtained. In addition, in two strains biofilm formation was decreased with increased lysozyme concentrations. Nisin reduced biofilm formation of four strains with increasing concentrations, but there was no effect of nisin on biofilm formation of the other strains. As a result of this study, lysozyme was determined as an ineffective biopreservative against S. aureus strains, but it can activate biofilm formation of the strains. Conversely, high concentrations of nisin had an inhibitory effect on bacterial growth, whereas the presence of nisin resistant S. aureus strains could exist. Key Words: Staphylococcus aureus , lysozyme, nisin, biofilm, food