Biomedical Engineering Reference
In-Depth Information
Table 2 Penicillium species
producing lignocellulose-
degrading enzymes
Species
References
P. decumbens
[
67
]
P. funiculosum
[
78
]
P. janthinellum
[
32
]
P. chrysogenum
[
79
]
P. canescens
[
80
]
P. purpurogenum
[
81
]
P. brasilianum
[
82
]
P. simplicissimum
[
83
]
P. citrinum
[
84
]
P. melinii
[
85
]
P. verruculosum
[
86
]
P. pinophilum
[
87
]
P. echinulatum
[
88
]
P. occitanis
[
89
]
P. minioluteum
[
90
]
Penicillium species were reported and their conditions for cellulase production
were optimized [
70
,
71
]. A strain producing alkaline cellulase was isolated and
studied by Chinese scientists [
72
]. Interestingly, this strain secretes cellulases with
an optimum pH of 9.5, making it potentially useful for hydrolyzing alkali-treated
biomass. To obtain halophilic or salt-tolerant cellulases, a megagenomic library
was constructed from environmental DNA samples and screened for potential
halophilic cellulases. An EG from glycoside hydrolase family 5 was identified
through this approach, and was cloned and expressed in Escherichia coli, and
purified. This purified protein was shown to be salt-tolerant and maintains about
70% residual activity after pretreatment with 4 M NaCl or KCl for 10 days [
73
].
In the search for thermostable cellulases, an attempt was made by Qin et al. [
74
]to
overexpress EG Cel5A from T. reesei in S. cerevisiae. This recombinant EG has
higher glycosylation content, as well as a dramatically better themostability at
50 C. In another study, Cel45A from P. decumbens was purified, the first such
attempt with a glycoside hydrolase family 45 protein; the enzyme was shown
to have an optimum temperature of 60 C and significantly hydrolyzes konjac
glucomannan, phosphoric acid-swollen cellulose, and sodium carboxyl methyl
cellulose, with the highest activity against the first substrate [
75
].
Penicillium species with the ability to produce high cellulase and hemicellulase
titers have been described [
8
,
64
,
76
,
77
]. They usually have higher bG activity
than Trichoderma sp. [
76
], making them potent for the hydrolysis of lignocellu-
losic materials. Interestingly, the enzyme from Penicillium sp. ECU0913,
which has both high cellulase and high hemicellulase activity, efficiently
hydrolyzes pretreated corn stover without any accessory enzymes [
61
]. Many
Penicillium strains that produce cellulolytic enzymes were found (Table
2
), of
which P. decumbens, P. janthinellum,, and P. funiculosum were the most studied.
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