However, there are at least two major technical obstacles to the
production of LA from lignocellulosic residues: (i) biomass pretreatment
and hydrolysis, and (ii) efficient fermentation of pentose
from lignocellulosic hydrolysates into LA. The use of lignocellulose
is extremely difficult because of its crystalline structure, which is
inaccessible to cellulose degradation. Several methods are used
to pretreat biomass: acid hydrolysis and steam can be used to
hydrolyze hemicellulose into fermentable mono- or oligosaccharides
by using high temperature or pressure conditions (Lloyd
and Wyman, 2005) and alkaline treatments (lime, wet-oxidation,
and soaking with ammonia) are effective in delignification, resulting
in solid residues of cellulose fibers and some hemicellulose
(Kim and Lee, 2007; Varga et al., 2003). Simultaneous saccharification
and fermentation (SSF) is favored over separate hydrolysis and
fermentation (SHF) when using pre-treated biomass for the production
of LA, since the glucose released following cellulase activity
in SSF is rapidly converted to LA by the fermenting
microorganism, thus minimizing end-product inhibition of cellulase
caused by glucose and cellobiose accumulation (John et al.,
2009).