THE PRODUCTION OF CELLULASE BY FUNGI ON MIXED CELLULOSIC SUBSTRATES

Fractionation of beta-glucosidases and related extracellular enzymes from Aspergillus niger

Industrial concentrates from Aspergillus niger culture filtrates were fractionated by ion-exchange and adsorption chromatography. Several other types of hydrolases were completely removed. Eight partially purified components were obtained. Using specific activity as an estimate of purification, one aryl-beta-glucosidase was purified 35-fold. Another component showed 147-fold purification using a viscosimetric assay with carboxymethylcellulose as substrate. The aryl-beta-glucosidase was distinctly more thermolabile than the carboxymethylcellulase.

Some cases of onychomycosis from north India in different working environments

Three fungi, Alternaria humicola, A. pluriseptata and Aspergillus niger are being reported as new probable etiologic filamentous fungi, causing onychomycosis. The morphology and physiology of these fungi is discussed.

Regulation of induced cellulase synthesis in Pyrenochaeta terrestris Gorenz et al. by utilizable carbon compounds

Cellulase (Cx) synthesis was inducible by Pyrenochaeta terrestris in liquid culture. Cellulase activities on various types and amounts of cellulose reached specific maximum plateaus which were maintained indefinitely. These plateaus were reestablished when the enzyme was diluted at each substrate concentration. The maximum levels appeared related to rates of cellulolysis. Above a low threshold rate of hydrolysate liberation, maximum Cx levels are ordered inversely to cellulolytic rates. Supplementing the inducer cellulose with glucose or related compounds above 5 × 10−4 M repressed synthesis nearly to the basal level. The evidence lends credence to a hypothesis that Cx synthesis by P. terrestris is regulated by an inducer:repressor mechanism.

ISOLATION, PURIFICATION, AND PROPERTIES OF CELLULASES FROM ASPERGILLUS TERREUS AND PENICILLIUM VARIABILE

Cellulases from A. terreus and P. variabile were isolated and purified nearly 100-fold. Enzyme production reached a maximum on the seventh day of incubation. The properties and activities of the purified cellulases were studied. At constant enzyme concentration, the activity increased with the increase in substrate concentration but the percentage of the substrate hydrolyzed decreased. Of the two purified cellulases, that from A. terreus seemed to be a purer product and was tested for its homogeneity and enzymic nature. A unienzymic nature was indicated by the observation that no resolution of the enzyme could be effected by electrophoresis. Standard solubility and diffusion tests gave no indication of heterogeneity in the purified cellulase; this finding was confirmed by the presence of only one peak in both gel filtration and ion-exchange chromatography. Random splitting of α-cellulose and carboxymethylcellulose (CMC) was indicated.