Disaccharides permeases: constituents of xylanolytic and mannanolytic systems of Aureobasidium pullulans

Aureobasidium pullulans, a yeast-like microorganism was found to produce mannobiose permease and xylobiose permease, transporting beta-1,4-mannobiose or beta-1,4-xylobiose into the cells from extracellular media. Both permeases are induced by the same inducers as the corresponding hemicellulolytic enzyme systems. Mannobiose permease is induced by beta-1,4-mannobiose or is formed in the cells growing on mannan (inducers of beta-mannanolytic enzymes) and xylobiose permease is induced by d-xylose, beta-1,4-xylobiose or during the growth on xylan (inducers of xylanolytic enzymes). The permeases are energy dependent, synthesized de novo and their activities are inhibited by d-glucose. Since mannobiose permease transports beta-1,4-mannobiose, xylobiose permease appears to be less specific and transports beta-1,4-mannobiose, beta-1,4-xylobiose and methyl beta-d-xylopyranoside. Methyl beta-d-mannopyranoside or methyl beta-d-xylopyranoside serve as less efficient inducers of the corresponding permeases than beta-1,4-mannobiose or beta-1, 4-xylobiose.