CHARACTERIZATION OF N-ACETYL-D-GLUCOSAMINE UPTAKE IN APHANOCLADIUM-ALBUM

A mutant of the fungus Aphanocladium album, characterized as chitinase -overproducing, does not grow on medium containing N-acetyl-D-glucosam ine as sole carbon source. The lack of growth may indicate a defect ei ther 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 com pared with those obtained with the wild-type strain. Labelling experim ents, designed to characterize N-acetyl-D-glucosamine uptake, indicate d that uptake was due to the simultaneous operation of two transport s ystems, one of high affinity and one of low affinity. Wild-type and mu tant strains displayed different K-m values for the low-affinity syste m. The K-m value of the mutant's low-affinity system was very high com pared with that of the wild-type strain.