Health hazards of Aflatoxin and virulent genes of Staph aureus enterotoxins in yoghurt

Abstract

Eighty random samples of plain and flavored yoghurt (40of each) were collected from differentsupermarkets in Menoufia Governorate. The collected samples were transferred immediately to thelaboratory in an icebox for mycological, bacteriological examination, estimation of aflatoxins producedby certain species of moulds and enterotoxins types A and D produced by Staph. aureus. Mould wasdetected in (82.5%) of plain yoghurt samples and (97.5%) of flavored yoghurt samples. Aspergillus andPencillium genera were frequently detected than other genera of fungi. Aspergillus spp. were the mostdominant in the contaminated samples, (40%) in both plain and flavored yoghurt followed by Pencilliumspp (30%) of plain yoghurt and (25%) of flavored yoghurt. Aspergillus spp. A. flavus and A. niger werethe major isolates. A. flavus was isolated from plain and flavored yoghurt with apercentages of 50% and62.5%, respectively. While, A. niger was (25% and 12.5%) from plain and flavored yoghurt,respectively. The four samples of plain yoghurt contaminated by A. flavus were analyzed for AFM1.They were positive in range from 0.049-0.472 ppb, while other four samples were free. Moreover,flavored yoghurt showed five samples contaminated with AFM1 in concentration of 0.061-0.586 ppb,while, other five samples were negative. The incidence of Staph. aureus in the collected plain andflavored yoghurt samples was 20% and 25%, respectively .The average count of Staph. aureus in theexamined plain and flavored yoghurt samples was 1.20x10³± 0.15x10³ and 1.53x10³± 0.22x10³ cfu/g,respectively. The isolated Staph. aureus from plain and flavored yoghurt produced SEA and SEDenterotoxins with a percentage of (12.5 % , 12.5 % , 10 % and 10 % ), respectively.