[The enzyme release by Trichophyton rubrum is dependent on nutritional substance supply]

Enzymes liberated by growing dermatophytes are of pathogenetic importance in tinea. To investigate the influence of nutrients on this enzyme release, Trichophyton rubrum was grown in media containing peptone, keratin and lipids, to which glucose was added in separate assays. The culture supernatants were compared for extracellular enzyme activities by use of the api-zym-test. Our results clearly show that the extracellular enzyme activity is dependent on the nutrients supplied. Seven different enzymes were released when keratin was supplied, as compared to only 5 and 2, respectively, when lipids or peptone were available. Among these enzymes alkaline phosphatase and N-acetyl-beta-glucosaminidase were detected in all cultures lacking glucose. Enzyme release was inhibited completely when glucose was added to the media, except for N-acetyl-beta-glucosaminidase in peptone cultures. This dependency of enzyme release on fungal nutrition can be expected to occur in vivo, too. In addition, it has to be considered for in vitro cultural conditions. Alkaline phosphatase and acetyl-glucosaminidase may be more important in tinea than has been assumed so far.