MYCELIUM-BOUND LIPASE FROM A LOCALLY ISOLATED STRAIN OF ASPERGILLUS-FLAVUS LINK - PATTERN AND FACTORS INVOLVED IN ITS PRODUCTION

Aspergillus flavus produces a lipase (EC 3.1.1.3) which is partly boun d to the mycelium during growth. The production of the mycelium-bound lipase is concomitant with growth, and declines when growth ceases. Ma ximum productivity of the enzyme is obtained when the culture is incub ated at 30 degrees C, an initial culture pH of 6.5 and with 2% (w/v) e ach of corn oil and yeast extract as carbon and organic nitrogen sourc e. Yeast extract affects not only the production of lipase but also th e secretion of proteases into the culture medium. Production of the la tter enzymes, which inactivate the free lipase, is enhanced by adding yeast extract (1-2%, w/v) to the culture medium. However, at 5% (w/v) yeast extract concentration, proteolytic activity is not detected and consequently, the activity of free lipase may easily be measured. Free lipase activity can easily be detected when 0.001 mol dm(-3) EDTA is added to the culture medium. The presence of the chelating agent enhan ces the production and maintains the stability of the extracted myceli um-bound lipase.