Lactococcus lactis in Dairy Fermentation—Health-Promoting and Probiotic Properties

The use of lactic acid bacteria (LAB) in the fermentation process to produce fermented foods has a long history. Furthermore, LAB are beneficial microorganisms known for their health-promoting characteristics. During fermentation, LAB have the capacity to produce significant amounts of bioactive substances, such as peptides, bacteriocins, lactic acid, exopolysaccharides (EPSs), enzymes, and others. Lactococcus lactis as one of the best-known and well-characterized species of LAB serves as a model organism for studying LAB. For a very long time, L. lactis has been used in milk fermentation, both in well-monitored industrial settings and on a small scale in traditional operations. Furthermore, L. lactis is a vital microorganism in the dairy food fermentation industry due to its role in acidification, flavor development, and the creation of various dairy products, including cheese, fermented butter, and others. The novelty of this review is the comprehensive and organized presentation of the main benefits of the use of L. lactis in milk fermentation processes including technological and safety features relevant for the dairy industry, probiotic potential, the ability to produce bioactive compounds (e.g., bacteriocins, GABA), and the recent development of such bacteria research methods like whole genome sequencing (WGS).