Background

Bile salts play critical roles in the human gastrointestinal tract, as influencers and modulators of the microbial composition throughout the gut. Bile salts are one of the primary components of bile, which is produced in the liver to aid in digestion of lipids. Gut microbiome bacterial species often express bile salt hydrolase (BSH) enzymes, which deconjugate bile acids. Deconjugation diminishes microbial toxicity of bile salts, and amino acids released during bile salt deconjugation can be utilized by bacteria as an energy source. Bacterial species with active BSH enzymes persist in the gut more effectively than species lacking BSH enzyme activity. BSH expression is common in probiotic lactobacilli.

Of note, various types of bile salts (conjugated, or not) comprise the