Page 208 - Lignocellulosic Biomass to Liquid Biofuels

Biobutanol from lignocellulosic biomass: bioprocess strategies 171

from biomass materials (then often termed as biobutanol or second-
generation biofuel), shows superior fuel properties than bioethanol
[20 22]. In 1912 14 the first industrial production of biobutanol was
explored via acetone, butanol, and ethanol (ABE) fermentation, using the
molasses as well as cereal grains in the presence of Clostridium acetobutylicum
(Weizmann’s microorganism), but the large-scale production of biobuta-
nol through microbial fermentation was reported by Louis Pasteur in
1861. Since the middle of the 20th century, some of the promising
microbial strains, say Clostridium beijerinckii, Clostridium saccharoperbutylaceto-
nicum, and Clostridium saccharobutylicum, have been identified and utilized
for the production of biobutanol with maximum yield, although currently
C. acetobutylicum has been widely utilized globally for the promising pro-
duction of biobutanol.
In this chapter, we discuss the production of biobutanol from lignocel-
lulosic biomass materials through (1) pretreatment and hydrolysis of differ-
ent solid lignocellulosic biomass materials, (2) effects of degradation
products on growth and biobutanol production by advanced ABE-
fermenting microbial strains, and (3) strategies for improving the produc-
tion of biobutanol.

5.2 Brief summary on lignocellulosic biomass material
properties and their chemical compositions

Generally, all the lignocellulosic biomass materials (mainly from forest
materials and residues, agricultural residues and grasses, starchy materials,
bioenergy crops, and municipal wastes) are potential organic resources and
are also utilized as an admirable rich source for the production of bio-oil
or biofuel, which is due to their massive amount (B70% 80%) of
fermentable sugar moieties [23]. Also, most of the commonly used cheap
lignocellulosic biomass materials used as feedstocks are corn stover, sugar-
cane bagasse, wheat straw, rice straw, etc. for the production of bio-oil in
developed as well as developing countries, say United States, South
America, North America, Asia, and Europe [24,25]. The bioconversion of
lignocellulosic biomass materials into bio-oils or valuable chemical com-
pounds via pretreatment, enzymatic hydrolysis followed by fermentation
processes are depicted in Fig. 5.1. The lignocellulosic biomass materials
comprise three major forms of significant polymers, namely, cellulose,
hemicellulose, and lignin, 30% 50%, 15% 35%, 10% 20%, respectively
[7,14,18,19], with trace amounts of others such as pectin, protein,