Farklı kalsiyum konsantrasyonlarının enterotoksijenik Bacteroides fragilis kökenlerinin üremesi üzerine etkisi

Amaç: Bu çalışmada kalsiyumun, çinkoya bağımlı metalloenzim yapısında enterotoksin salgılayan Bacteroides fragilis (B. fragilis) kökenlerinin üremesi üzerine etkili olup olmadığını araştırmak amaçlanmıştır. Yöntem: Enterotoksijenik B. fragilis (ETBF) bakterilerinden bft1 ve bft2 genleri taşıyan ikişer köken ve toksini olmayan bir B. fragilis çalışmaya alınmıştır. Kalsiyum klorür (CaCl2) ve çinko klorür (ZnCl2) tuzlarının her birinin bu bakterilerin üremesine etkisi kantitatif kültürler ile araştırılmıştır. Bunun için, gerek normal gıdalarla alındığında, gerekse gıdalara ek olarak, günde 1 gram kalsiyum alındığında, barsak içeriğindeki kalsiyum konsantrasyonlarını temsil edecek, farklı tuz konsantrasyonlarıyla hazırlanmış besiyerleri kullanılmıştır. Bakterilerin farklı tuz konsantrasyonlarında üreme verilerinin istatistiksel analizi Kruskal Wallis ve Mann-Whitney U testleriyle yapılmıştır. Bulgular: Kalsiyum klorür tuzları tüm ETBF kökenlerinin üremesi üzerine inhibitör etki yapmıştır. Özellikle yüksek düzeyde CaCl2, bft2 + geni taşıyan kökenlerin koloni sayısında belirgin azalmaya neden olmuştur (p=0,002). İstatistiksel olarak anlamlı bir fark yaratmamakla beraber, ZnCl2, tuz bulunmayan kontrol besiyerindeki kültürlere göre daha fazla sayıda koloni oluşumuna yol açmıştır.Sonuç: Bulgularımız, kalsiyumun ETBF kökenleri üzerine antimikrobiyal etkisinin olabileceğini göstermektedir; ancak kalsiyumun, bakterinin enterotoksik etkisinde herhangi bir değişiklik yapıp yapmadığının araştırılması gerekmektedir.

Investigation of the effect of different calcium concentration on the growth of enterotoxigenic Bacteroides fragilis strains

Objective: The aim of the present study was to investigate whether calcium was effective on the growth of enterotoxigenic Bacteroides fragilis (ETBF) which produces a zinc-dependent metalloenzyme. Methods: A total of four ETBF strains (two bft1 +, two bft2 + strains) and one nontoxigenic Bacteroides fragilis (B. fragilis) were tested. Individual effects of calcium (CaCl2), and zinc (ZnCl2) chloride salts on growth of these strains were carried out with quantitative cultivation. In order to assess potential activities of different salt concentrations on growth parameters and dose-response profiles of the strains, media with different salt concentrations which represent the normal and high dose calcium intake levels as in intestines, were used. The data were analyzed by using Kruskal Wallis and Mann-Whitney U tests.Results: Calcium salts exerted inhibitory effect on the growth of all ETBF strains; particularly, high level of CaCl2 resulted in significant decrease in the number of bacterial colonies of bft2 + strains (p=0,002). Although not statistically significant, slightly more colonies were grown on the culture media with ZnCl2 when compared with the medium without salt.Conclusion: Our results indicate the presence of an antimicrobial effect of calcium on ETBF strains, however, whether calcium leads to a change on the enterotoxic effect remains to be established.
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