of biomass prior to the bioconversion process is compulsory.
Consequently, several chemical (acid, alkaline and organosolv pretreatment,
wet oxidation), physical (mechanical pretreatment,
pyrolysis, microwave), physicochemical (ammonia fiber explosion,
steam explosion, carbon dioxide explosion, liquid hot water) and
biological lignin removal methods have been suggested [3–6].With
the exception of bio-treatments, the majority of these methods suffer
disadvantages like difficult operating conditions (such as high
pressure, temperature and pH), production of inhibitors or hazardous
wastes and having harmful side effects [7]. On the other
hand, the most significant drawback of the biological methods is
their low efficiency and slow rate of lignin removal which hindered
their application in the large scale [8]. Evidently, improving the effi-
ciency and low rate of delignification besides the other inherent
merits of the biological pretreatment makes it a potentially proper
option.
Fungi which are capable of producing ligninolytic enzymes play
the key role in biological pretreatments. They can biodegrade lignin
and increase the accessibility of cellulose in the biomass structure.
As a result, the modified biomass is more susceptible to enzymatic
digestion [9,10]. It has been shown that lignin can be degraded
by a ligninolytic system mainly consists of lignin peroxidase (LiP),
manganese peroxidase (MnP) and laccase (Lac) [11–14] and the
involved mechanism in the biodegradation of lignin through this
system has been well understood [