Probiotics are defined as "living microorganisms, which upon ingestion in certain numbers exert health benefits on the host beyond inherent basic nutrition." They have been shown to alleviate lactose intolerance, influence intestinal flora, stimulate immunity, reduce inflammation, lower cholesterol, and prevent various diseases. Probiotics are increasingly used as biotherapeutic agents due to their perceived safety and natural origin. Selecting effective probiotic strains for the gastrointestinal tract is challenging, with in vitro tolerance to physiological stresses like bile being a key criterion. Molecular studies are now exploring the genetic basis of gastric survival and functionality. Bile salt hydrolase (BSH) activity is a key trait in probiotic strains, as it helps in deconjugating bile acids, which can have both beneficial and potentially harmful effects. BSH activity is present in various bacteria, including Lactobacillus, Bifidobacterium, and Enterococcus. However, the role of BSH in probiotics is still debated, as it may affect bile tolerance and host health. BSH enzymes are part of the Ntn hydrolase family and are involved in the hydrolysis of bile acids, which can influence bacterial survival and host physiology. BSH activity is associated with the ability of bacteria to hydrolyze bile salts, which can affect their survival in the gastrointestinal tract. BSH-positive strains may have an advantage in bile tolerance, but there are concerns about the potential negative effects of BSH activity on the host. The presence of multiple BSH homologs in some bacteria suggests a possible advantage in adapting to different bile environments. BSH activity may also contribute to cholesterol lowering by reducing the reabsorption of bile acids, thus decreasing serum cholesterol levels. The impact of BSH activity on the host includes potential benefits such as cholesterol reduction and reduced bile toxicity, but there are also concerns about the possible negative effects of BSH activity on the host. The role of BSH in probiotic bacteria is still under investigation, and future research may lead to the development of more effective probiotics with improved survival and functionality in the gastrointestinal tract. The study highlights the importance of understanding BSH activity in probiotics and its potential applications in improving human health.Probiotics are defined as "living microorganisms, which upon ingestion in certain numbers exert health benefits on the host beyond inherent basic nutrition." They have been shown to alleviate lactose intolerance, influence intestinal flora, stimulate immunity, reduce inflammation, lower cholesterol, and prevent various diseases. Probiotics are increasingly used as biotherapeutic agents due to their perceived safety and natural origin. Selecting effective probiotic strains for the gastrointestinal tract is challenging, with in vitro tolerance to physiological stresses like bile being a key criterion. Molecular studies are now exploring the genetic basis of gastric survival and functionality. Bile salt hydrolase (BSH) activity is a key trait in probiotic strains, as it helps in deconjugating bile acids, which can have both beneficial and potentially harmful effects. BSH activity is present in various bacteria, including Lactobacillus, Bifidobacterium, and Enterococcus. However, the role of BSH in probiotics is still debated, as it may affect bile tolerance and host health. BSH enzymes are part of the Ntn hydrolase family and are involved in the hydrolysis of bile acids, which can influence bacterial survival and host physiology. BSH activity is associated with the ability of bacteria to hydrolyze bile salts, which can affect their survival in the gastrointestinal tract. BSH-positive strains may have an advantage in bile tolerance, but there are concerns about the potential negative effects of BSH activity on the host. The presence of multiple BSH homologs in some bacteria suggests a possible advantage in adapting to different bile environments. BSH activity may also contribute to cholesterol lowering by reducing the reabsorption of bile acids, thus decreasing serum cholesterol levels. The impact of BSH activity on the host includes potential benefits such as cholesterol reduction and reduced bile toxicity, but there are also concerns about the possible negative effects of BSH activity on the host. The role of BSH in probiotic bacteria is still under investigation, and future research may lead to the development of more effective probiotics with improved survival and functionality in the gastrointestinal tract. The study highlights the importance of understanding BSH activity in probiotics and its potential applications in improving human health.