Lactic acid bacteria, the full name of which is lactobacillus, is a single-celled prokaryote.

Lactic acid bacteria is a kind of probiotics, which can ferment carbohydrates into lactic acid, hence its name. Lactic acid bacteria are widely distributed and usually exist in meat, milk, vegetables and other foods and their products. In addition, lactic acid bacteria also widely exist in the intestines of livestock and poultry and a few clinical samples. Among them, lactic acid bacteria in the oral cavity and intestines of human beings and other mammals are important members of normal microbial flora in specific areas.