초록
<P><B>Abstract</B></P> <P>To valorize oleaginous <I>Schizochytrium</I> sp. biomass, a novel sequential process was addressed and developed to simultaneously produce high value DHA-enriched glycerides and low value bulky biodiesels. In this process, <I>Schizochytrium</I> sp. biomass was first treated by alkaline protease; then the resulting biomass was directly subjected to enzymatic ethanolysis catalyzed by liquid enzymes from <I>C. antarctica</I> (CALA), <I>T. lanuginosus</I> (TL), <I>R. miehei</I> (RM) and <I>A. oryzae</I> (PLA). For all four liquid lipases, the alkaline protease treatment on <I>Schizochytrium</I> sp. biomass significantly enhanced total lipid recovery, biodiesel yield and yield of DHA-enriched glycerides. Under optimized conditions, CALA and TL achieved the highest biodiesel yields 76.28–76.66 wt% based on microalgae TFAs while PLA had the lowest (55.25 wt%). Moreover, CALA attained the highest DHA (77.93 wt%) and LC PUFAs (93.08 wt%) contents in glyceride fraction, suggesting a superior performance to concentrate DHA and LC PUFAs in glycerides. <SUP>13</SUP>C NMR analysis illustrated that non-regiospecificity and unfavorability towards LC PUFAs of CALA made it possible to transesterify saturated fatty acids located in all 3 positions of microalgal oil; thus LC PUFAs were highly enriched in glycerides. Overall, the sequential process using enzymes and ethanol as green media was successfully established for the co-production of high-value microalgal bioproducts rich in LC PUFAs and sustainable biodiesels in a comprehensive manner.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel sequential process was developed for DHA enrichment and biodiesel. </LI> <LI> <I>Schizochytrium</I> sp. biomass was selected as the raw material. </LI> <LI> CALA was a promising enzyme in view of biodiesel yield and DHA enrichment. </LI> <LI> CALA achieved 76.28 wt% biodiesel conversion under optimal conditions. </LI> <LI> The highest DHA and LC PUFAs contents in glycerides were 77.93 and 93.08 wt%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>