Inductive conditions of lipase by Aspergillus oryzae and its localization in a cell

Conditions of lipase production by Aspergillus oryzae IFO-4202 were studied by solid media, such as sardine meal with added soluble starch and boiled rice for “Koji” substrate, and liquid media modified Czapek-Dox medium. The localization of lipase in cells was also investigated. When the “koji” was prepared from the sardine meal with added soluble starch, A. oryzae preferentially utilized the added soluble starch rather than lipid of sardine meal. Since the lipase activity increased with a decrease of soluble strach content, it was indicated that A. oryzae utilized the lipid contained in the sardine meal at the period. Lipase activity in the liquid media with olive oil was repressed with glucose, whereas the activity appeared markedly in the presence of 5-10% olive oil without glucose. Under the latter conditions, it was shown that both intracellular lipase and extracellular lipase were induced by lipid. It was suggested that the intracellular lipase was a cell superficial enzyme localized in periplasm at the earlier stage of cultivation, stayed there for a definite period (10-12h), and was then released the outside of cells as extracellular enzyme.