Isolation and Genotypic Identification of Some Spoilage and Pathogenic Microbes from Yogurt

Document Type : Original Article


1 Food Hygiene Dept. Animal Health Research Institute Benha lab ARC Egypt

2 Food Hygiene and Control Department, Faculty of Veterinary Medicine, Benha University, Egypt

3 Bacteriology Dept., Animal Health Research Institute, ARC, Egypt


The study was planned to evaluate the prevalence of E. coli, E. faecalis, B. cereus, mold and yeast in a total of 200 yogurt samples (Commercial and Balady yogurt types, 100 of each) which were be taken from different supermarkets and dairy shops at Qalubiya Governorate, Egypt. Bacteriological results revealed that, 27(13.5%) isolates were recovered from 200 yogurt samples, 8 (4.0%) E. coli (2 strains of E. coli O86a H4, 3 strains of E. coli O119 H4, and 3 strains of E. coli O153 H2); 11(5.5%) E. faecalis and 8 (4.0%) B. cereus. Meanwhile, mycological results cleared that, 80 fungal isolates represented as: 37 molds (19 Aspergillus niger, 5 Aspergillus fumigatus, 5 Mucor spp., 3 Aspergillus flavus, 3 Penicillium spp. and 2 Rhizopus spp. ) and 43 yeasts (23 C. albicans, 12 Rhodotorula spp. and 8 C. tropicalis) were isolated from both brand and balady yogurt. PCR results showed that, phoA virulence genes was detected in E. coli strains and stx1 gene was detected in one strain only, meanwhile, stx2 gene failed to be amplified in examined strains; the16SrRNA, esp and gelE genes were detected in all E. faecalis strains and the groEL, cytK and nhe genes were detected in all B. cereus strains. The study was concluded that, some of the examined yogurt samples have risky role in transmission of pathogenic bacteria (E. coli, E. faecalis, B. cereus), as well as mold and yeast to humans that considered as serious health hazard.


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