Abstract
Studies on the biosynthesis and biodegradation of biotin and their regulation in microorganisms are reviewed. The pathway of biotin biosynthesis is as follows : pimelic acid → pimelyl-CoA → 7-keto-8-aminopelargonic acid → 7, 8-diammopelargomc acid- dethiobiotin → biotin. All the enzymes involved in the reactions from pimelic acid to dethiobiotin were characteried and found to be regulated by biotin through feedback repression. Mycoplana sp. No. 166 having the highest biotin-degrading ability was isolated from soil. The metabolites from biotin and dethiobiotin were isolated and identified by mass and NMR spectral analyses. New biotin and dethiobiotin metabolites found were β-hydroxybisnorbiotin, β-hydroxydethiobiotin, and tetranordethiobiotinyl ketone. These results indicated that the degradation of biotin is initiated by β-oxidation of its side chain. Biotinyl-CoA synthetase, the first enzyme involved in β-oxidation of the side chain; was purified to homogeneity. The enzyme was a monomeric enzyme with a molecular weight and an isoelectric point of about 55,000 and 4.85, respectively. The purified enzyme catalyzed stoichiometric conversion of biotin, ATP, and CoA into biotinyl-CoA, AMP, and PPi. Dethiobiotin and actithiazic acid, a synthetic biotin analog, were also effective as substrates. Biotinyl-CoA could be used as substrate for acyl-CoA oxidase and α-dehydrobiotinyl-CoA was produced. The authors attempted to establish the production of α-dehydrobiotin and the enzymatic determination of biotin using two enzymes, biotinyl-CoA synthetase and acyl-CoA oxidase. A mutant strain of Bacillus sphaericus. AB 12, resistant against actithiazic acid and 5-(2-thienyl)-valeric acid was obtained and found to excrete biotin 7.1 times as much as the wild type strain. Recent studies progressed on biotin production by bacteria transformed by recombinant DNA, are also reviewed.
