초록
<P><B>Abstract</B></P> <P>The pyruvate carboxylase-encoding <I>PYC1</I> gene from the yeast strain <I>Aureobasidium</I> sp. P6, which is a polymalate over-producer, was actively overexpressed in the marine-derived yeast <I>Aureobasidium melanogenum</I> 9-1, which is a heavy oil (liamocin) producer. The resulting <I>PYC1</I>-over-expressing transformant M39 produced 35.3 ± 1.2 g/l liamocins and 24.6 ± 0.5% (w/w) intracellular oil, and its cell dry weight was 17.0 ± 1.6 g/l. On the other hand, wild-type strain 9-1 only produced 27.4 ± 0.3 g/l liamocins and 22.6 ± 0.8% (w/w) intracellular oil and had a cell dry weight of 15.3 ± 2.0 g/l within 168 h. The results suggested that the over-expression of the <I>PYC1</I> gene enhanced the biosynthesis of liamocins and intracellular lipids in transformant M39 due to the enhanced biosynthesis of citric acid, which could be the precursor for the biosynthesis of the intracellular lipids and extracellular liamocins. During fermentation, 43.04 ± 1.2 g/l of extracellular liamocins, 17.7 ± 0.5 g/l of cell dry weight and 23.8 ± 0.2 g/l of intracellular lipids were produced by transformant M39 within 156 h, leaving 2.1% reducing sugar in the fermented medium. Moreover, the strong alkaline hydrolysis products of the extracellular liamocins mainly contained 5-hydroxy-2-decenoic acid lactone (92.1 ± 0.3%), hexadecanoic acids (C<SUB>16:0</SUB>, 3.3 ± 0.04%), octadecadienoic acids (C<SUB>18:2</SUB>, 1.0 ± 0.2%) and octadecanoic acids (C<SUB>18:0</SUB>, 3.6 ± 0.01%), while the intracellular lipids mainly contained C<SUB>16:0,</SUB> C<SUB>16:1</SUB>, C<SUB>18:0</SUB>, C<SUB>18:1</SUB> and C<SUB>18:2</SUB> fatty acids.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A transformant M39 over-expressing the <I>PYC1</I> gene could produce 43.04 ± 0.4 g/l of liamocin, and 23. 8 ± 0.2% (w/w) of intracellular lipids. </LI> <LI> The alkaline hydrolysis products of the liamocin contained mainly 5-hydroxy-2-decenoic acid lactone;. </LI> <LI> The intracellular lipids contained mainly C<SUB>16:0,</SUB> C<SUB>16:1</SUB>, C<SUB>18:0</SUB>, C<SUB>18:1</SUB> and C<SUB>18:2</SUB> fatty acids. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Biosynthesis enhancement of liamocins and intracellular lipids by overexpressing <I>PYC1</I> gene.</P> <P>[DISPLAY OMISSION]</P>