Abstract: A method for quantitative or qualitative determination of at least one fungus of interest in a sample where use is made of an assay that determines enzymatic activity derived from the fungus. In addition, an enzyme inhibitor that preferentially inhibits the corresponding enzymatic activity in other cells potentially present in the sample is added so as to minimize false positive enzyme activity measurements from these other cells. Also a kit comprising a substrate for the enzyme to be determined and an inhibitor of the enzyme activity is provided.

Abstract: A method for selectively determining a fungal biomass by detection of a fungal enzymatic activity that is present in substantially all fungal species, such as enzymes involved in chitin metabolism (chitinase, chitin synthase, chitosanase, N-acetyl-glucosaminidase and &bgr;-N-acetylhexosamidase). The invention can be used for detecting a fungal biomass in environmental samples, food products, plant material, building materials, industrial fungal cultures or sample from a human being or animal including blood samples. In particular, 4-methylumbelliferyl-N-acetyl-&bgr;-D-glucosaminide is used as substrate for &bgr;-N-acetylhexosamidase (EC 3.2.1.52). This enzyme activity correlates with the amount of fungal biomass present in a sample.