[Cultivation conditions of the Aspergillus terricola mutant producing proteolytic enzyme]

The effect of temperature, aeration and various foam suppressors on the growth of a mutant of Aspergillus terricola H-20 and on its production of proteolytic enzymes was studied. A high level of the proteolytic activity (12-15 PU/ml) was found at 28-30 degree C in conditions of aeration with the rate of oxygen dissolution being 0.38-0.86 g of oxygen per litre per hour. Synthesis of the enzyme was inhibited by a decrease in temperature to 22-24 degree C, a surplass (1.07 g O2 per litre per hour) or insufficient (0.18 g O2 per litre per hour) content of oxygen in the medium, and by addition of animal (sperm-whale) fat as a froth breaker to the medium. The best rate of protease biosynthesis was obtained upon stepwise addition of sunflower oil to the cultural broth. The best synthetic froth breakers for biosynthesis of the proteolytic enzyme are adecanol at a concentration of 0.1-1% and polymethylsiloxane PMS-A 154 as a water emulsion at a concentration of 0.5% of the medium volume.