Application of lactic acid bacteria in the markets are divided into four categories: dairy industry, health food industry, animal feed industry and pharmaceutical industries. Recently, Lactobacillus acidophilus have been used in the food industry and have obtained great attention as key cultures for health benefit. Since commercial application of L. acidophilus has become a common practice, characterization of these cultures were made. Futhermore, the strains selected should produce a final dairy product possessing good taste and acceptable body and texture, a selection step that cannot be achieved unless the product is actually manufactured. Conjugated linoleic acid (CLA) have been recognized as antioxidants, cancer inhibitors, cholesterol depressing agents, and growth promoting factors. Food products from ruminants, particularly dairy products, are the major dietary source of CLA f3r humans. The CLA content in yogurt or cheese can be increased by action of the starter cultures. The finding of the production of CLA by food starter culture opens interesting perspectives far the future in producing fermented products enriched in CLA.