Bacillus coagulans is a gram-positive, rod-shaped bacterium that produces L-lactic acid through homolactic fermentation. Approved as safe by the FDA, it regulates intestinal flora, inhibits harmful microorganisms, and is resistant to gastric acid, bile salts, and high heat. It survives well in low-oxygen environments and is used widely in feed for poultry, livestock, aquatic animals, and ruminants.