Examination of toxin production from environmental Bacillus cereus and Bacillus thuringiensis

Abstract

Emetic toxin- and entero toxin-producing activities were examined for 524 strains of Bacillus cereus and 90 strains of Bacillus thuringiensis to determine the distribution and contamination in natural environment, including foods, vegetable, soil and etc. Emetic toxin was assayed by the production of acid from HEp2 cells induced by the culture supernatants of Bacillus, which was developed as an improved method for the detection of B. cereus heat-stable emetic-toxin by us. In the 524 strains of B. cereus tested, 11 out of 60 strains obtained from bean paste and 5 out of 20 strains obtained from peach produced emetic toxin which was detected by the HEp-2 cell method. All these emetic toxin-producing isolate strains were classified into H1 serotype. The 90 strains of B. thuringiensis did not produce emetic toxin, but the 47 strains produced entero toxin.