초록
<P><B>Abstract</B></P> <P>Itaconic acid is a naturally produced organic acid with diverse applications as a replacement for petroleum derived products. However, its industrial viability as a bio-replacement has been restricted due to limitations with native producers. In this light, <I>Yarrowia lipolytica</I> is an excellent potential candidate for itaconic acid production due to its innate capacity to accumulate citric acid cycle intermediates and tolerance to lower pH. Here, we demonstrate the capacity to produce itaconic acid in <I>Y. lipolytica</I> through heterologous expression of the itaconic acid synthesis enzyme, resulting in an initial titer of 33mg/L. Further optimizations of this strain via metabolic pathway engineering, enzyme localization, and media optimization strategies enabled 4.6g/L of itaconic acid to be produced in bioreactors, representing a 140-fold improvement over initial titer. Moreover, these fermentation conditions did not require additional nutrient supplementation and utilized a low pH condition that enabled the acid form of itaconic acid to be produced. Overall yields (0.058g/g yield from glucose) and maximum productivity of 0.045g/L/h still provide areas for future strain improvement. Nevertheless, this work demonstrates that <I>Y. lipolytica</I> has the potential to serve as an industrially relevant platform for itaconic acid production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Heterologous expression of CAD allows for 33mg/L itaconic acid in <I>Yarrowia lipolytica</I>. </LI> <LI> Pathway engineering and media optimization improved titer to 670mg/L. </LI> <LI> Bioreactor fermentations increased titer to 4.6g/L (140-fold total improvement). </LI> <LI> Achieved yield of 0.058g/g from glucose and maximum productivity of 0.045g/L/h. </LI> <LI> Cytosolic aconitase overexpression greatly improves itaconic acid production. </LI> </UL> </P>