Page 284 - Refining Biomass Residues for Sustainable Energy and Bioproducts

252 Refining Biomass Residues for Sustainable Energy and Bioproducts

superior emission and combustion properties when compared to gasoline. Industrial pro-
duction of itaconic acid is carried out with A. terreus using glucose as the sole carbon
source. Itaconic acid production by metabolically engineered Neurospora crassa using
lignocellulosic biomass was evaluated by Zhao et al. (2018). Cis-aconitic acid decarbox-
ylase gene was heterologously expressed in N. crassa to synthesize itaconic acid. The
engineered strain was capable of producing itaconic acid (20.41 mg/L) directly from lig-
nocellulosic biomass.
Itaconic acid production from biomass hydrolyzate using Aspergillus strains was
reported by Jime ´nez-Quero et al. (2016). Acid and enzymatic hydrolyzates were
evaluated for the production of itaconic acid. Maximum itaconic acid production
(0.14%) was observed when submerged fermentation was carried out with corncob
hydrolyzate by A. oryzae. The study reveals the possibility of SSF of biomass for
the production of itaconic acid.
Klement et al. (2012) evaluated itaconic acid production by Ustilago maydis
from hemicellulosic fraction of pretreated beech wood. One of the advantages of U.
maydis is that the strain grows as yeast-like single cells, and it can survive under
high osmotic stress. The study revealed that under mild pretreatment conditions, U.
maydis would be a promising candidate for itaconic acid production. Fine tuning of
pretreatment conditions should be carried out for the improved production of itaco-
nic acid.

11.2.4.4 Xylonic acid

Xylonic acid is a platform chemical that finds applications in agriculture, food,
and pharmaceutical industries. It is used as a precursor for hydrogels, 1,2,4-
butanetriol, polyesters, etc. There are two strategies for the production of
xylonic acid—chemical and enzymatic routes. Yim et al. (2017) engineered
Corynebacterium glutamicum for the bioconversion of xylan to xylonic acid in a
single-step process. The lower efficiency occurs due to an incomplete degradation
of xylan to xylose.
Production of xylonic acid from hemicellulosic hydrolyzate using an artificial
enzyme complex was evaluated by Lee et al. (2017). Rosettazymes, an artificial
enzyme complex, comprising four different enzymes, such as endoxylanase,
α-glucuronidase, β-xylosidase, and xylose dehydrogenase, were developed to
hydrolyze glucuronoxylan to D-xylonic acid. The study revealed that colocalizing
the enzymes into a scaffold is insufficient for product enhancement.

11.2.4.5 Succinic acid
Succinic acid is a dicarboxylic acid that finds applications in food industry, green
solvents, etc. Lignocellulosic biomass serves as a low-cost feedstock for the produc-
tion of succinic acid. The cost of raw material plays a significant role in the overall
process economics. Corn stalk, cane molasses, etc. serve as suitable lignocellulosic
biomasses for the production of succinic acid.