Studies on Anaerobic Bacteria in Some Cheeses Sold in Assiut City, Egypt

Abstract

A total of 200 random samples of Kareish, Domiati, Ras and Processed cheese (50 samples each) were collected from different dairy shops and supermarkets in Assiut City-Egypt, from February 2011 to May 2012 for the presence of anaerobes. By using plate method technique their percentages were 92, 96, 100 and 90% with average counts of 4.1×103,1.3×10³, 2.7×10³ and 4.5×10²/g, respectively. Cl. species as Cl. ramosum, Cl. perfringens, Cl. difficile, Cl. innoculum, Cl. septicum, Cl. novyi type A, Cl. cadaveris, Cl. sporogenes, Cl. hastiforme, Cl. butyricum and Cl. subterminale were identified in various percentages from the concerning samples. Cl. perfringens were recorded in percentages of 12, 2, 22 and 10% with average counts of 3.7×10, <10, 8.4 and 2.2×10²/g, respectively by using MPN technique however, Cl. botulinum failed to be detected. Moreover, Cl. perfringens type A enterotoxines were determined by using enzyme linked immunosorbent assay (ELISA). Two samples of Ras cheese were positive with optical density of 0.262 and 0.314. In addition, lysozyme (Delvozyme) at concentration of 250 IU was found to be highly effective on growth rate of the vegetative form of Cl. perfringens. Public health as well as economical importance of detected microorganisms in the locally manufactured cheeses was discussed.