97
cose [57]. It is tolerant to IA and can overcome the feedback inhibition problem.
Otten et al. have explored the capability of C. glutamicum for glucose-based synthesis of IA [58]. They produced genetically engineered C. glutamicum immobilization
of A. terreus CadA with E. coli maltose-binding protein. These modifications
boosted the activity of C. glutamicum, resulting in IA titers of 7.80 g L
−1
under
nitrogen-limited growth conditions.
2.2.3 IA Production by Yeasts
When compared to fungi and bacteria, yeasts have some additional advantages
including lower energy requirements, lower susceptibility to infectious agents, and
ability to perform post-translational modifications. Despite such impressive features, little advancements have been made in utilization of yeast to produce IA. Few
examples of IA production using yeast are described below.
Yarrowia lipolytica Yarrowia lipolytica (Y. lipolytica) is an oleaginous yeast for
efficient production of IA [59]. In 2015, Alper et al. first demonstrated the inherent
activity of Y. lipolytica to produce IA [60]. Different parameters such as media,
enzyme localization, and metabolic pathways were screened and optimized to
obtain 4.6 g L
−1
titers of IA from glucose in a bioreactor. They found that Y. lipolytica is capable of growing under low pH and high-shear stress conditions.
Motivated by this work, Zhao et al. enhanced the activity of Y. lipolytica by overexpressing a series of genes [61]. The overexpression of mitochondrial cis-aconitate
transporter (MTT) gene substantially altered the organic acid profile of Y. lipolytica.
The engineered strain produced 22.03 g L
−1
IA from glucose which is the highest
achieved from yeast under industrially relevant conditions.
Saccharomyces cerevisiae Saccharomyces cerevisiae (S. cerevisiae) is a nonpathogenic yeast known for its rapid growth, high tolerance to shear stress, and high
pH resistance properties [62]. Blazeck et al. proposed a systematic approach for the
synthesis of IA by S. cerevisiae [63]. In this approach, a hybrid promoter was first
used to optimize pathway expression within S. cerevisiae. Next, three effective
genetic targets were identified by in silico computational genome-scanning analysis. This collective approach resulted in IA productivity of 0.16 g L
−1
from glucose.
Young et al. applied iterative algorithm to develop substantial strain libraries that
improves IA yield [64]. The most promising pathways to IA were identified through
automated strain construction in which three libraries were designed to screen different parameters. This algorithmic design strategy produced 0.85 g L
−1
IA, the
highest yet reported by yeasts. Two other known IA producer yeasts are Pseudozyma
antarctica and the genus Candida. P. antarctica was the most active and produced
30 g L
−1
IA from glucose in flask fermentation under nitrogen-limited growth conditions [65, 66].
Bio-Catalytic Itaconic Acid and Bio-Based Vinyl Monomer Production Processes
cose [57]. It is tolerant to IA and can overcome the feedback inhibition problem.
Otten et al. have explored the capability of C. glutamicum for glucose-based synthesis of IA [58]. They produced genetically engineered C. glutamicum immobilization
of A. terreus CadA with E. coli maltose-binding protein. These modifications
boosted the activity of C. glutamicum, resulting in IA titers of 7.80 g L
−1
under
nitrogen-limited growth conditions.
2.2.3 IA Production by Yeasts
When compared to fungi and bacteria, yeasts have some additional advantages
including lower energy requirements, lower susceptibility to infectious agents, and
ability to perform post-translational modifications. Despite such impressive features, little advancements have been made in utilization of yeast to produce IA. Few
examples of IA production using yeast are described below.
Yarrowia lipolytica Yarrowia lipolytica (Y. lipolytica) is an oleaginous yeast for
efficient production of IA [59]. In 2015, Alper et al. first demonstrated the inherent
activity of Y. lipolytica to produce IA [60]. Different parameters such as media,
enzyme localization, and metabolic pathways were screened and optimized to
obtain 4.6 g L
−1
titers of IA from glucose in a bioreactor. They found that Y. lipolytica is capable of growing under low pH and high-shear stress conditions.
Motivated by this work, Zhao et al. enhanced the activity of Y. lipolytica by overexpressing a series of genes [61]. The overexpression of mitochondrial cis-aconitate
transporter (MTT) gene substantially altered the organic acid profile of Y. lipolytica.
The engineered strain produced 22.03 g L
−1
IA from glucose which is the highest
achieved from yeast under industrially relevant conditions.
Saccharomyces cerevisiae Saccharomyces cerevisiae (S. cerevisiae) is a nonpathogenic yeast known for its rapid growth, high tolerance to shear stress, and high
pH resistance properties [62]. Blazeck et al. proposed a systematic approach for the
synthesis of IA by S. cerevisiae [63]. In this approach, a hybrid promoter was first
used to optimize pathway expression within S. cerevisiae. Next, three effective
genetic targets were identified by in silico computational genome-scanning analysis. This collective approach resulted in IA productivity of 0.16 g L
−1
from glucose.
Young et al. applied iterative algorithm to develop substantial strain libraries that
improves IA yield [64]. The most promising pathways to IA were identified through
automated strain construction in which three libraries were designed to screen different parameters. This algorithmic design strategy produced 0.85 g L
−1
IA, the
highest yet reported by yeasts. Two other known IA producer yeasts are Pseudozyma
antarctica and the genus Candida. P. antarctica was the most active and produced
30 g L
−1
IA from glucose in flask fermentation under nitrogen-limited growth conditions [65, 66].
Bio-Catalytic Itaconic Acid and Bio-Based Vinyl Monomer Production Processes