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Biobutanol from lignocellulosic biomass: bioprocess strategies 185

5.5 Production of biobutanol through microbial or acetone,
butanol, and ethanol fermentation process
The production of biobutanol from the microbial fermentation process is
more superior to the usual chemical routes [12,109,110], because this pro-
cess is a more eco- as well as environment-friendly approach, and the uti-
lized biological materials or feedstocks could reduce the GHG emissions.
Hence, the microbial or ABE fermentation process is the promising tool
for the production of eco-friendly biobutanol in many biofuel plants using
the lignocellulosic feedstocks (corn cobs, corn stover, etc.) due to their
high abundance, renewability, carbon richness, inexpensive nature, etc.
[111]. The first and oldest industrial large-scale production of biobutanol
via ABE fermentation using Clostridium strains (C. acetobutylicum)
[102,112] and the biofuel plant was first developed in the United
Kingdom in 1912. Prof. Chaim Weizmann (called the father of industrial
fermentation for developing ABE fermentation process) developed the
large-scale production of biobutanol from C. acetobutylicum in industrial
sectors. During the ABE fermentation process, three major classes of pro-
ducts are formed, namely, (1) solvents (ABE), (2) organic acids (acetic, lac-
tic, and butyric acids), and (3) gases (CO 2 and H 2 with 60:40 mole ratio)
[12,113]. The main metabolic pathways for the production of biofuels
through ABE fermentation of Clostridia are shown in Fig. 5.4.

5.6 Concluding remarks and future outlook
In the middle of the 20th century, many researchers and industrialists
reported the low productivity of ABE products or biobutanol production
from different lignocellulosic biomass feedstocks via ABE fermentation
process. Currently, the utilization of enhanced pretreatment and geneti-
cally engineered processes has modified ABE fermentation process.
Advanced recovery tools for the separation as well as purification of bio-
butanol with high yield will lead to an improved yield and production of
ABE products or biobutanol. This could make the produced biobutanol a
promising fuel resource for the replacement of petroleum-based fuels. In
the current age the problems as well as challenges in the production of
ABE products or biobutanol are feedstock availability (say inexpensive,
renewable, high abundance, high fermentable sugar moieties), economical
and environment-friendly advanced pretreatment and hydrolysis processes,
eco-friendly or economic feasibility of ABE fermentation, and recovery of