Incidence and toxigenic profile of Bacillus cereus in some fishes

Abstract

A total of 300 fish samples were collected from Giza and Cairo shops, supermarkets and restaurants. These samples were 150 raw fish samples of Tilapia, Mackerel and Sardine (50 for each) and 150 ready to eat fish samples of fried Tilapia, grilled Mackerel and grilled Sardine (50 for each). Each sample was subjected to bacteriological and molecular examination for detection of Bacillus cereus and its toxins. The obtained results using PCR indicated that the incidence of B. cereus in raw Tilapia, Mackerel and Sardine were 24% (12/50) , 26% (13/50) and 40% (20/50) respectively ; while for hemolytic toxin was 75% (9/12) , 62% (8/13) and 60% (12/20) , non-hemolytic toxin was 25% (3/12) , 38% (5/13) and 40% (8/20), cytotoxin K was 16.5% (2/12), 15% (2/13) and 0 and Cereulide was 16.5% (2/12) , 7.5% (1/13) and 5% (1/20) in positive samples of B. cereus in raw Tilapia, Mackerel and Sardine respectively. In ready to eat Tilapia, Mackerel and Sardine the incidence of B. cereus were 20% (10/50) , 18% (9/50) and 30% (15/50) respectively ; while for hemolytic toxin were 07% (0/07) ,67% (6/9) and 73% (11/15) , non-hemolytic toxins were 30% (3/10) ,33% (3/9) and 27 % (4/15) in in positive samples of B. cereus in ready to eat Tilapia , Mackerel and Sardine respectively. In this study we didn't detected any cytotoxin K or cereulide toxins genes in any of the ready to eat fish samples.