Some factors affecting ureolytic activities in Aspergillus fumigatus and Fusarium nivalis

ABSTRACT

Governing the cultural conditions of Ashergiilus fumigatus and Fusarium nivale led to significant differences in the growth and subsequently ureolytic activities either in the culture media or in the assay reaction mixtures of both species. Glucose was found to be the most suitable carbon source but its optimum concentration varied in both fungi. It was 6% in As fumigatus and 4% in F. nivale. Considering nitrogen sources, urea when used as a sole nitrogen source, was accompanied with higher growth and ureolysis in the two fungi than when any of the other tested nitrogenous compounds added. The optimum urea concentration was 6.5 glL in A. fumigatus and 4.5 g/L F. nivale. Among the different phosphate compounds tested, [NH4]2 HPO4at 1g PO4[3]-/L Was the most favourable for maximum crease [s] activities and growth in both fungi. Not only sulphate concentration was different in the test fungi, but also its source varied. [NH4] 2SO[2] at 0.5 gSO42+/L was optimum for A. fumigatus growth and ureolysis, while MgSO4 at 0.3 g SO4[2]-/L was the optimum in F. nivale