I have done a lot of reasearch on SBO's lately. The two most commonly used in products for human consumption are bacillus subtilus and bacillus lichenformis. These are the 2 SBO's in Primal Defense, and Nature's Biotics. In fact these organisms PRODUCE large amounts of enzymes, that is why they can clean the inside of your intestines out. They are used in commericial industries to make enzyme supplements for animal feed, and in cleaning products (the enzymes break down carbohydrates, proteins, and fats). If you are sensitive to enzymes in general, that is most likely why you cannot tolerate these organisms.