Studies of Aspergillus fumigatus; casein precipitating and proteolytic effects of mycelial filtrate.

(1900) and (1903) seem to have been the first to focus attention on the proteolytic activity of micro-fungi. The occurrence and properties of proteolytic enzymes from various fungus species were subsequently studied by several authors. Literature in this field was reviewed by e.g. (1950), (1955), (1957), (1960), (1963) and (1965). In connection with investigation of the proteolytic activity of several fungus species, a gelatin hydrolyzing effect of Aspergillus fumigatus (AF) was reported to be exerted by living organisms in pure culture 1931), extracted mycelial material 1950, 1952), and by fluid culture medium in which AF was cultured 1950a, b, (1943) demonstrated moderate casein hydrolyzing activity in extracted mycelial material from 4 AF strains, and (1955) observed low fibrinolytic activity in 1 strain. Proteolytic activity measured by breakdown of gelatin and casein was demonstrated by (1964) in culture medium in which AF had been cultured. Three activity optima were observed at pH values around 3, 6.5 and 10. A subsequent study indicated that the activity in neutral and alkaline environment was caused by the same enzyme 1965). By means of electrophoretic separation combined with reactions for enzyme characterization, (1966) demonstrated proteolytic activity in mycelial extracts of 21-day AF cultures. A casein precipitating enzyme (CP enzyme) was demonstrated by (1967) in the fluid phase of frozen and thawed skimmilk agar cultures from e.g. AF. In addition to haemolysin and toxin 1965, 1968, 1966), mycelial filtrates of AF have proved to contain a proteolytic enzyme. An account is given in the following of a study of this enzyme with respect to (1) casein precipitating ability, (2) casein and gelatin hydrolyzing effect, and (3) relation to toxin and haemolysin.