Liquid-surface immobilization system and liquid-liquid interfacebioreactor: Application to fungal hydrolysis

Novel fungal cultivation and bioconversion systems are proposed. Sporesand mycelia of a fungus suspended in a liquid medium were effectively floatedon a liquid surface by the aid of a ballooned microsphere (MS). Many fungisuch as Aspergillus and Penicillium formed a thick and physicallystrong fungus-MS mat on the liquid surface followed by stationary cultivation(LSI). The fungus-MS mat of Absidia coerulea IFO 4423 was overlaid by asolution of 2-ethylhexyl acetate ( 1) in n-decane (liquid-liquidinterface bioreactor, L-L IBR). The strain could efficiently catalyze thehydrolysis of 1 to 2-ethyl-1-hexanol ( 2). The accumulation of 2 in the L-LIBR was significantly higher than those in emulsion and organic-aqueous two-liquid-phase systems and a formerly reported interface bioreactor (solid-liquid interface bioreactor, S-L IBR). Furthermore, lipase production in theLSI system was also higher than that in a submerged cultivation system.