Lactobacillus is a genus of rod-shaped bacteria, part of the lactic acid bacteria group. Most of the lactobacillus bacteria are benign and a number are associated with many health benefits. These bacteria live in the intestines and carry out important health functions. For example, they ferment fiber and converts it into short chain fatty acids - these can protect against cancer. In addition, they make the intestinal environment acidic; inhibiting the growth of harmful bacteria.