초록
<P><B>Abstract</B></P> <P> <I>Yarrowia lipolytica</I> Wt-11 producing an extracellular lipase was isolated and identified. To improve the lipase production, <I>Y. lipolytica</I> Wt-11 was subjected to low-energy ion implantation mutation breeding, and a best mutant, <I>Y. lipolytica</I> Mut-96, was obtained after screening. Under the optimal cultivation conditions, the scaled-up production of lipases were performed, and the lipase activity of <I>Y. lipolytica</I> Mut-96 was enhanced nearly 5.5-fold compared with that of <I>Y. lipolytica</I> Wt-11. After fermentation, the lipases were purified, and the characteristics of the purified lipases were studied. The optimum temperatures and pHs for lipases from Wt-11and Mut-96 were 30°C and 8.0, respectively. The purified lipases were stable between pH 7.0 and 8.5 and unstable at temperatures above 40°C. The lipase activities were enhanced by Ca<SUP>2+</SUP>, Ba<SUP>2+</SUP>, Mn<SUP>2+</SUP>, Fe<SUP>2+</SUP> and SDS. The synthesis of L-ascorbyl palmitate via esterification with L-ascorbic acid and palmitic acid by immobilized lipases from Wt-11 and Mut-96 in organic media was investigated, and the L-ascorbyl palmitate can be respectively produced at levels of 14.8 and 27.5g/L.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A newly isolated strain that produces an extracellular lipase was identified as <I>Yarrowia lipolytica</I> Wt-11. </LI> <LI> <I>Y. lipolytica</I> Mut-96 with higher lipase activity were obtained by mutation breeding after screening. </LI> <LI> The synthesis of L-ascorbyl palmitate catalyzed by lipases in organic media was investigated. </LI> <LI> The L-ascorbyl palmitate can be produced by purified Wt-11 and Mut-96 lipases at 14.8 and 27.5g/L. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>