Characterization of N-acetyl-D-glucosamine uptake in Aphanocladium album

Abstract

A mutant of the fungus Aphanocladium album, characterized as chitinase-overproducing, does not grow on medium containing N-acetyl-D-glucosamine as sole carbon source. The lack of growth may indicate a defect either in the uptake system or in any subsequent step in the metabolism of N-acetyl-D-glucosamine. Since transport is the first step at which control of metabolism could operate, the mutant strain was studied for its ability to transport N-acetyl-D-glucosamine. The results were compared with those obtained with the wild-type strain. Labelling experiments, designed to characterize N-acetyl-D-glucosamine uptake, indicated that uptake was due to the simultaneous operation of two transport systems, one of high affinity and one of low affinity. Wild-type and mutant strains displayed different Km values for the low-affinity system. The Km value of the mutant's low-affinity system was very high compared with that of the wild-type strain.Key words: deuteromycete, filamentous fungus, Aphanocladium album, uptake, N-acetyl-D-glucosamine.