Influence of nutritive substrate and pH on catalase and peroxidase production in saprophytic fungus Rhizopus nigricans

Aerobic organisms are vulnerable to action of reactive oxygen species that are very noxious and may be responsible for damage of all cellular constituents. Most organisms have developed defense mechanisms to protect cells from high levels of free radicals. The purpose of this paper is to determine the antioxidant response in fungus Rhizopus nigricans, materialized trough enzymatic activity of biochemical markers of oxidative stress – catalase and peroxidase. We followed the influence of culture medium pH and nutrient substrate on development of the two enzymes. Enzymatic assays were performed at intervals of 5, 10 and 15 days, using both fungus mycelium and culture liquid. Development of the fungus was completely inhibited at pH 2. Catalase and peroxidase production was mostly endocellular because in the culture liquid in most work variants enzymatic assay was not possible and in the remaining work variants were recorded low values for catalase and extremely low, near to zero for peroxidase.