Maximum cellulase production in Aspergillus terreus was obtained at a temperature of 28 "C, pH 4.0 and a substrate concentration of I % CMC. Variability in cellulase enzyme production and isozyme polymorphism of endo-p-1,4-glucanase and p-1,4-glucosidase was studied in 45 natural isolates of A. terreus.
Different electrophoretic patterns were evident for endoglucanase. Three zones of activity viz EG I , EG I I and EG I I 1 were observed showing different electrophoretic mobilities. Some of the isolates exhibited the presence of null alleles for EG 1. During development EG 1 and EG 1 I were observed throughout while EG I 1 1 appeared on the eighth day. For /3-1,4-glucosidase two zones of activity viz p-glu 1 and p-glu I I were observed. p-glu 1 showed variable electrophoretic mobilities. p-glu 1 appeared throughout during development while p-glu 11 appeared on the twelfth day.
--m B
## Results
Maximum production of cellulases in A. terreus was obtained on 1 % CMC at a temperature of 28 "C and pH 4.0.
## Isozyme expression during growth
The fungus was grown on pectin for 24 days. Extracellular and intracellular fractions were electrophoretically analysed.
## Expression of endo-/3-1,4-glucanase
During the initial stages of growth two zones EG 1 and EG 11 were observed and a third zone EG 11 1 appeared on the 81h day. All the three isozymes persisted upto 24Ih day. Intensity of bands increased with development. In the intracellular fraction same pattern was observed but the intensity of bands was very low (Fig. A and B).
## Expression of /3-1,4-glucunase
During cultivation p-glu 1 was present throughout the cultivation with same intensity in the extracellular fraction while /3-glu 11 appeared after 121h day and persisted till the termination
EG-Ul