THE USE OF FLUOROGENIC SUBSTRATES FOR MEASURING ENZYME-ACTIVITY IN PEATLANDS

The fluorogenic model substrates, methylumbelliferyl [MUF]-beta-D-gluc oside, MUF-phosphate and MUF-sulphate, were used to investigate the ac tivities of beta-glucosidase, phosphatase and sulphatase, respectively , in Welsh peatland soils. The method was used to investigate depth de pendent variations in enzyme activity in a riparian wetland, and flush channel wetland. The highest activities were found at depths of less than 10 cm, thus confirming other studies which suggest this upper dep th to be the site of greatest microbial activity. The most serious lim itation to the technique was found to be the (fluorescence) quenching effects of the phenolic materials that dominate peatland dissolved org anic carbon. The problem necessitates the adoption of a time consuming quench correction procedure with every sample. Fluorogenic substrates have led to a greater understanding of the role of enzymes in other a quatic systems. It seems likely that they will prove of equal value in elucidating their role in nutrient cycling and the biogeochemistry of peatlands.