Birnbaum, Jerome (University of Cincinnati, Cincinnati, Ohio), and Herman C. Lichstein. Metabolism of biotin and analogues of biotin by microorganisms. III. Degradation of oxybiotin and desthiobiotin by Lactobacillus plantarum. J. Bacteriol 92:920–924. 1966.—Lactobacillus plantarum growing in excess oxybiotin degraded a portion to products not utilizable by Saccharomyces cerevisiae. The loss of activity for the yeast suggested that no vitamers of oxybiotin accumulated during the degradation. The initiation of degrading activity was controlled by the pH of the growth medium and appeared during early stationary phase. Only cells grown in excess oxybiotin could degrade this biotin analogue. Nonproliferating cells grown previously in excess oxybiotin were able to convert biotin to vitamers (active for the yeast) as well as to degrade oxybiotin. Those grown in excess biotin also developed the ability to degrade oxybiotin as well as to convert biotin; however, in this case, the enzymes degenerated more rapidly. Cells grown with excessive amounts of either material were able to degrade desthiobiotin to products not available for the yeast. Both biotin conversion and oxybiotin degradation were found to have the same requirements for Mg and Mn ions. It was concluded that conversion of biotin to vitamers, and the degradation of oxybiotin or desthiobiotin are functions of the same on closely related enzyme systems.