Lactose fermentation is a biological process where certain microorganisms, like lactic acid bacteria, convert lactose, a sugar found in milk, into lactic acid. This process occurs in environments with low oxygen levels and is commonly used in the production of dairy products such as yogurt and cheese. During lactose fermentation, the breakdown of lactose not only produces lactic acid but also helps preserve food by lowering its pH, which inhibits the growth of harmful bacteria. This fermentation process is essential for individuals who are lactose intolerant, as it reduces the lactose content in dairy products, making them easier to digest.