Page 283 - Refining Biomass Residues for Sustainable Energy and Bioproducts

Agroresidue-based biorefineries 251

lactic acid production was observed with a barium hydroxide catalyst pretreated OFB
with a lactic acid yield of 21.57%. Pretreatment conditions were 5% biomass loading,

incubation temperature of 240 C, and an incubation time of 4 h.
Consolidated bioprocessing of lignocellulosic biomass for the production of lac-
tic acid using a synthetic fungal bacterial consortium was evaluated by Shahab
et al. (2018). The study indicates the direct conversion of lignocellulosic biomass to
lactic acid. A synthetic cross-linked consortium was developed between lactic acid
bacteria and aerobic fungus Trichoderma reesei for cellulolytic enzymes. The con-
sortia produced 34.7 g/L of lactic acid from 5% w/w of microcrystalline cellulose.
In consolidated bioprocessing the consortia simultaneously utilizes both hexoses
and pentoses, which results in a higher yield of lactic acid (19.8 g/L). The results
demonstrate the possibility of a consortium-based consolidated bioprocessing strat-
egy for the cost-effective production of lactic acid.
Zhang et al. (2016) demonstrated the potential of an engineered Lactobacillus
plantarum for the production of lactic acid from lignocellulosic biomass. Alkali-
pretreated corn stover and sorghum stalks were evaluated for the production of
lactic acid. Sequential saccharification and simultaneous saccharification and cofer-
mentation (SSCF) were evaluated and the results indicate that SSCF eliminates
feedback inhibition with a lactic acid yield of 27.3 and 22 g/L from corn stover and
sorghum stalks, respectively. Lactic acid production from corn stover hydrolyzate
by a mutant strain of Bacillus coagulans GKN316 was reported by Jiang et al.
(2016). The highest yield was observed as 45.39 g/L. The study revealed that the
mutated strain of B. coagulans GKN316 can effectively grow in nondetoxified
hydrolyzate with a better yield of lactic acid.

11.2.4.2 Fumaric acid

Fumaric acid is one of the top 12 biomass-derived platform chemicals. It is widely
used as a food additive. Jime ´nez-Quero et al. (2016) developed a strategy for the
production of fumaric acid using corncob by solid-state fermentation and SSF using
Aspergillus terreus and Aspergillus oryzae. Under optimized conditions, A. oryzae
produced 0.54 mg/g of fumaric acid. Li et al. (2018) reported the production of
fumaric acid using corncob. The cellulose-rich fraction of the corncob was used for
the production of fumaric acid by Rhizopus oryzae in fed-batch SSF. Under opti-
mized conditions the strain produced 35.22 g/L of fumaric acid. Mass balance stud-
ies revealed that 100.6 g of fumaric acid were produced from 1000 g of corncob
dry matter. Oil palm EFB serves as a good source for the production of fumaric
acid by isolate K20 (U-thai et al., 2016). Under optimized conditions the strain K20
produced 5.3 g/L of fumaric acid.

11.2.4.3 Itaconic acid
Itaconic acid or methylene succinic acid is a high-value platform chemical that finds
application in polymer industry, wastewater treatment, and ion-exchange chromatography
sector (Willke and Vorlop, 2001). It can be converted to 3-methyltetrahydrofuran that has