INTRACELLULAR AND EXTRACELLULAR ENZYME-ACTIVITY IN SOIL WITH REFERENCE TO ELEMENTAL CYCLING

Enzyme activities play an important role for the transformation of;:el ements and compounds in soil and, thus, were extensively analyzed for more than 4 decades. The activity of any enzyme in soil may not only b e controlled by active organisms. Substantial parts of 'extracellular' enzymes may be stabilized by abiotic soil components maintaining thei r activity. Methods to discriminate the source of enzyme activity were summarized with emphasis on the approach plotting enzyme activity ver sus a feature integrating the microbial biomass after the addition of glucose and nitrate. Considering the quotient between enzyme activity and microbial biomass content, protease activity will be discussed wit h reference to nitrogen transformation in soils.