A probiotic strain reduces serum cholesterol by deconjugating bile acids. What enzymatic activity underlies this effect?

Correct answer: (d) Bile-salt hydrolase

Explanation

Bile acids are joined (conjugated) to glycine or taurine in the liver. Some probiotic bacteria make the enzyme bile-salt hydrolase (BSH), which splits this bond and frees the bile acids.

Free (deconjugated) bile acids are absorbed back less well and more of them are lost in the faeces. The liver then uses more cholesterol to make new bile acids, so the blood cholesterol level falls.

• Urease splits urea into ammonia and CO₂.
• Catalase breaks down hydrogen peroxide.
• Beta-galactosidase splits lactose.