Bacterial degradation of biotin. Catabolism of 14C-biotin and its sulfoxides.

A biotin-degrading particulate system has been obtained by sonic rupture of a soil pseudomonad which grows on d-biotin as sole source of carbon, nitrogen, and sulfur. Investigation of the catabolism of l*C-biotin and its sulfoxides in this system has revealed the following. Degradation of biotin to CO2 is enhanced in the bufferwashed particulate preparations by addition of adenosine triphosphate, Mg2+, nicotinamide adenine dinucleotide, and coenzyme A. Maximal activation is found with 10es M nicotinamide adenine dinucleotide. Production of CO2 from ureido carbonyl and aliphatic carboxy1 portions of biotm and biotin d-sulfoxide is effectively inhibited by azide but is decreased only slightly by high concentrations of acetate or malonate. Oxybiotin, homobiotin, norbiotin, dethiobiotin, and the diaminocarboxylate from biotin moderately inhibit degradation of biotin and its dsulfoxide. L-Cysteine is effective as an apparent inhibitor, but this amino acid is very actively metabolized in the particulate preparations. Biotin and both dand I-sulfoxides of biotin are efficiently catabolized by the particulate preparations and exhibit mutual competition as substrates. Production of CO2 is most rapid from biotin d-sulfoxide, whereas the I-sulfoxide is somewhat less active than biotin. Very little degradation of biotin sulfone or diaminocarboxylate occurs. Oxybiotin, homobiotin, and norbiotin are not catabolized. Several catabolites of biotin have been isolated from incubation mixtures by column and paper chromatography.