Evidence for natural transformation of Bacillus subtilis in foodstuffs.

The effect of foodstuffs on the natural transformation of Bacillus subtilis was investigated. As examples of complex food matrices milk with various fat contents as well as chocolate milk were used. The frequencies of transformation varied with the fat content and ranged between 3.8 X 10(-4) and 1.4 X 10(-3). Highest frequencies of about 3 X 10(-3) were observed in chocolate milk with 1.5% fat. Development of competence was observed in chocolate milk, resulting in maximal transformation frequencies upon incubation for 10-12 h at 37 degrees C.