What exactly are probiotics?

Probiotics are live microorganisms that, when administered in adequate amounts, confer health benefits on the host. One of the basic criteria for selecting probiotic microorganisms, including bacteria, is their ability to survive in the host's body. Adhesion, i.e. the ability of microorganisms to adhere to the intestinal mucosa, enables the colonization of the gastrointestinal tract, and thus extends the probiotic action and contributes to improving the microbiological balance of the gastrointestinal tract. Other features, such as resistance to low pH or bile salts, production of various metabolites, including substances against other, competing microorganisms, also determine the ability of bacteria to survive in the gastrointestinal tract of animals or humans. Adhesion also allows for direct contact between microorganisms and epithelial cells, which is an important factor in many of the health-promoting effects observed with probiotic strains. During the lesson, we will introduce lactic acid bacteria, a group of microorganisms that includes the largest number of probiotic bacterial strains. We will show what their cells look like, how to investigate their probiotic properties using simple microbiological and biochemical tests, and talk about research on probiotics that use modern omics techniques (genomics, metagenomics, transcriptomics, proteomics and metabolomics).