Utilization of α-methyl-D-mannoside by Bacillus popilliae

Abstract

α-Methyl-D-mannoside (α-MM) was used by all acetate-oxidizing strains of B. popilliae tested at a growth limiting rate after a prolonged induction period. Those strains which did not oxidize acetate could not use α-MM for growth unless it was present at a high concentration. The period of induction was decreased, the rate of growth increased, and the extent of oxidation decreased as the α-MM concentration was increased. Theoretical levels of O2 uptake and CO2 evolution for the complete oxidation of the mannose moiety of α-MM were observed when the concentration of α-MM was low. Studies with resting cells and cell extracts demonstrated that an α-glucosidase was induced in B. popilliae by either α-MM or α-methyl-D-glucoside (α-MG). The enzyme was induced more rapidly by α-MG than by α-MM. Similarly, the ability of cells to oxidize α-MM was induced more efficiently by α-MG than by the mannoside. The data indicate that the hydrolysis of both α-MG and α-MM may be catalyzed by the same enzyme, but that the affinity for α-MG is much higher than that for the mannoside. The slow hydrolysis of α-MM by this enzyme is believed to account for the type of growth response observed.