Enzymatic studies of the thermophilic hydrocarbon utilizing fungi strains Aspergillus fumigatus and Mucor lusitanicus (author's transl)

The activities of catalase, peroxydase, and of the chitinolytic enzymes of the thermophilic hydrocarbon-utilizing fungal strains of Aspergillus fumigatus and Mucor lusitanicus, grown in n-alkane (KW) or glucose (Glc) medium at different temperatures with additions of KCN, NaNO3, 3-amino-1,2,4-triazole (ATA), and CaCl2 and with a shift culture from Glc to KW medium were determined. The enzymatic activities, able to cleave H2O2, were cytochemically shown in the hyphae with 3,3-diamino-benzidine-tetrahydrochloride (DAB) reagent. The colouring of the mycelium was most intense during the linear growth phase in the KW medium. The DAB oxydation could completely by suppressed by pre-incubation of the mycelium with the enzyme inhibitors KCN or ATA and incubation in the standard medium without H2O2. The catalase and peroxydase activities were higher in the KW medium than in the Glc medium, where highest activities occurred at the start of the linear and the stationary growth phase. The pre-incubation of the enzyme solution with the inhibitors KCN, NaNO2 or ATA gave maximum inhibition with ATA, likewise gave the addition of ATA to the medium the highest inhibition of the enzymatic activities, connected with an extension of the initial growth phase. Addition of CaCl2 increased the catalase and peroxydase activities, where catalase at 40 degrees C and peroxydase at 50 degrees C showed maximum growth. A shift of the growing mycelium from Glc to KW medium confirmed the correlation of KW utilization and high catalase activity. The highest chitinolytic activities were ascertained at the beginning of the linear growth phase at a temperature of 40 degrees C. The results were discussed.