Incidence and Effect of Nutritional Conditions on the Growth Rate of Emetic Toxin- Producing Bacillus cereus Isolated from Some Selected Food Products in Nigeria
The incidence, characteristics, and effect of nutritional factors on the growth rate of emetic toxin-producing B. cereus isolated from various food products marketed in Nigeria were examined. A total of one hundred and thirty food products which included processed rice based food fermented milk products, traditional condiments and vegetables were analyzed. Seventy-five of 130 (57.7 %) analyzed samples were found positive for Bacillus cereus. The highest incidence (84.0 %) occurred in traditional condiments followed by processed rice based food (67.5 %). Emetic toxin was produced by 7.3 % (6 of 82) of the isolated strains. The growth of three emetic Bacillus cereus strains was examined on different carbon and nitrogen sources. All the three emetic Bacillus cereus strains had the highest growth rate when using 10-12 g/L of glucose and 1.5-2.5 g/L of yeast extract as carbon and nitrogen sources respectively. The carbon and nitrogen sources had significant effect on the growth of the three emetic B. cereus strains. The results of this study highlight the low incidence of emetic Bacillus cereus strains within and among various Nigerian food products. However, the presence of emetic Bacillus cereus strains in these food products is a concern to public health.