Any of the rod-shaped, gram-positive (seegram stain) bacteria that make up the genus Lactobacillus. They are widely distributed in animal feeds, manure, and milk and milk products. Various species are used commercially in the production of sour milks, cheeses, and yogurt. Lactobacilli also play an important role in the manufacture of fermented vegetables (pickles and sauerkraut), beverages (beer, wine, and juices), sourdough breads, and some sausages. They inhabit but do not damage animal and human intestinal tracts. Commercial preparations of lactobacilli are used to restore normal intestinal flora after antibiotic therapy.