초록
<P><B>Abstract</B></P> <P>The conversion of lignocellulosic biomass (LCB) to microbial oils is attracting a growing amount of attention. However, the growth of the oleaginous yeast <I>Rhodotorula glutinis</I> on LCB hydrolysate (mainly rice straw) only will lead to a low lipid mass fraction, in the range of 10–20%. This study shows that the addition of crude glycerol to the LCB hydrolysate medium can efficiently raise the lipid mass fraction to the range of 30–40%. Crude glycerol is a by-product in the biodiesel production process. The use of renewable LCB hydrolysate and crude glycerol would greatly reduce the substrate cost for microbial oil production using <I>R. glutinis</I>. In addition, the results of experiments show that a low-cost airlift bioreactor is a more suitable fermentation process for the growth of <I>R. glutinis</I> than the use of a conventional agitation tank. When using mixed carbon sources of LCB hydrolysate with 30 kg m<SUP>−3</SUP> of reducing sugars and 30 kg m<SUP>−3</SUP> of crude glycerol, a maximal cell mass of 21.4 kg m<SUP>−3</SUP> and lipid mass fraction of 58.5 ± 6.2 were achieved in an internal loop airlift bioreactor, and this process may have the potential to be applied in scale-up production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A low-cost airlift bioreactor is a more suitable fermentation process. </LI> <LI> A mixed carbon sources of LCB hydrolysate with the addition of crude glycerol is suggested. </LI> <LI> The cells can still accumulate more total lipids with the addition of crude glycerol. </LI> <LI> The lipid content was significantly enhanced by adding crude glycerol in the medium. </LI> </UL> </P>