Investigations on the Degradation of the Bile Salt Cholate via the 9,10--Pathway Reveals the Formation of a Novel Recalcitrant Steroid Compound by a Side Reaction in sp. Strain Chol11.

Bile salts such as cholate are steroid compounds from the digestive tracts of vertebrates, which enter the environment upon excretion, e.g., in manure.

Comparative Analysis of Bile-Salt Degradation in sp. Strain Chol11 and Pseudomonas stutzeri Strain Chol1 Reveals Functional Diversity of Proteobacterial Steroid Degradation Enzymes and Suggests a Novel Pathway for Side Chain Degradation.

The reaction sequence for aerobic degradation of bile salts by environmental bacteria resembles degradation of other steroid compounds. Recent findings show that bacteria belonging to the use a pathway variant for bile-salt degradation. This study addresses this so-called Δ-variant by comparative analysis of unknown degradation steps in sp.

Degradation of Bile Acids by Soil and Water Bacteria.

Bile acids are surface-active steroid compounds with a C carboxylic side chain at the steroid nucleus. They are produced by vertebrates, mainly functioning as emulsifiers for lipophilic nutrients, as signaling compounds, and as an antimicrobial barrier in the duodenum. Upon excretion into soil and water, bile acids serve as carbon- and energy-rich growth substrates for diverse heterotrophic bacteria.

Functional Characterization of Three Specific Acyl-Coenzyme A Synthetases Involved in Anaerobic Cholesterol Degradation in Sterolibacterium denitrificans Chol1S.

The denitrifying betaproteobacterium Chol1S catabolizes steroids such as cholesterol via an oxygen-independent pathway. It involves enzyme reaction sequences described for aerobic cholesterol and bile acid degradation as well as enzymes uniquely found in anaerobic steroid-degrading bacteria. Recent studies provided evidence that in , the cholest-4-en-3-one intermediate is oxygen-independently oxidized to Δ-dafachronic acid (C-oic acid), which is subsequently activated by a substrate-specific acyl-coenzyme A (acyl-CoA) synthetase (ACS).