METHOD OF DETERMINATION OF CELLULASE ACTIVITY IN SOILS AND IN MICROBIAL CULTURES, AND ITS CALIBRATION

A new method has been developed for determining cellulase activity (CA ) in soils and in microbial cultures. This procedure is based on the m easurement of the loss in strength of a cellophane membrane (Proc. USS R Acad. Sci. Ser. Biol. 3 (1988) 466-471) and has been calibrated with cellulase enzyme activity, so that it is now possible to relate the d ecline in membrane strength to units of cellulase enzyme. The calibrat ion curve was used to convert the data obtained in relative units (atm h(-1)) to standard enzymatic units (mu g reduced sugars (red.sug.) ml (-1) h(-1)). Using group-specific antibiotics: actidione and chloramph enicol the method was applied to estimate the differential contributio n of soil fungi, bacteria and extracellular enzymes to cellulose decom position in soil. The CA was measured in: pure cultures of fungi, Tric hocladium asperum and Acremonium charticola (from 0.106 to 0.319 mu g red.sug. ml(-1) h(-1)), soil samples (0.158 and 0.176 mu g red.sug. ml (-1) h(-1)) and in situ, for a vertical profile (5-30 cm) of an oligot rophic bog (0.058-0.005 mu g red.sug. ml(-1) h(-1)), and in several wa tershed forest soils (from 0.158 to 0.206 mu g red.sug. ml(-1) h(-1)).