198
J. A. Elegbede and A. Lateef
Rai and Panda (2015) studied the reaction of commercial cellulase produced by
Trichoderma ressei ATCC 26,921 with silver ions in both aqueous and non-aqueous
media which produced stable narrow-sized AgNPs at room temperature. The redox
potentials of residues of tyrosine and protein backbone reportedly played an active
function in the bioreduction and cellulase was said to function as the capping ligand
that enabled stabilization of the AgNPs even in methanol. The probable mechanism
for the reduction was proposed as resulting from interaction of the residues of amino
acid present in cellulase (composed of 344 amino acid) and silver ions which probably
when coordinated to groups having residues of amino acid such as -NH, -SH and
-OH groups were subsequently reduced by them. Meanwhile, Xie et al. (2007b)
reported that Au(III) or Ag(I) ions could be reduced by Tyr residues; thus, cellulase
containing 14 Tyr residues and other residues with reduction properties can also act as
a robust reducing agent. Moreover, Gholami-Shabani et al. (2014) utilized purified
nitrate reductase produced by Fusarium oxysporum for the biogenic synthesis of
AgNPs which used gelatin as a capping agent. The purified enzyme with a molecular
weight of 214 KDa as projected by gel filtration on Sephacryl S-300 biosynthesized
the AgNPs in a NADPH-dependent mode. The AgNPs synthesized were spherically
natured with an mean size of 50 nm and were studied for antimicrobial activities using
the disk-diffusion method which displayed strong growth inhibitory activity against
all tested human pathogenic bacteria and fungi as evident from inhibition zones that
ranged from 14 to 25 mm. Also, lignin peroxidase produced by Acinetobacter sp.
was purified via diethyl aminoethyl cellulose ion exchange, then by Biogel P-150 gel
filtration column chromatography and employed for the biogenic synthesis of AgNPs.
The purified lignin peroxidase which had molecular weight of 99 kDa and consisted
of dimers of two polypetides of 23.9 and 24.6 kDa as proven by native and SDS-PAGE
upon reduction of Ag ions was reported to produced spherical polydispersed AgNPs
of 50 nm in dimension as observed under TEM (Singh et al. 2017). Furthermore,
Mishra and Sardar (2012) reported the eco-friendly fabrication of AgNPs using pure
alpha-amylase obtained from Aspergillus oryzae. Results obtained displayed that the
AgNPs having a peak of 422 nm in UV–Vis spectrum was characterized by TEM to
be monodispersed, hexagonally and triangularly fashioned with sizes ranging from
22–44 nm. Deepak et al. (2011) reported that purified fibrinolytic enzyme (URAK)
generated by Bacillus cereus NK1 was employed for biosynthesizing AgNPs within
24 h which was significantly reduced to 5 min upon the addition of NaOH solution.
The AgNPs biosynthesized was reported to absorb maximally at 440 nm under the
UV–Vis spectrum. Also, the AgNPs were said to be crystalline, spherically shaped
with mean size of 60 nm.
2.5.2 Gold Nanoparticles (AuNPs)
El-Batal et al. (2015) described the synthesis of laccase generated by Pleurotus
ostreatus by means of SSF. The production was optimized using factorial design
and the laccase produced was partially purified, characterized and applied for the
biofabrication of AuNPs. The biosynthesis led to the development of a violet-colored
J. A. Elegbede and A. Lateef
Rai and Panda (2015) studied the reaction of commercial cellulase produced by
Trichoderma ressei ATCC 26,921 with silver ions in both aqueous and non-aqueous
media which produced stable narrow-sized AgNPs at room temperature. The redox
potentials of residues of tyrosine and protein backbone reportedly played an active
function in the bioreduction and cellulase was said to function as the capping ligand
that enabled stabilization of the AgNPs even in methanol. The probable mechanism
for the reduction was proposed as resulting from interaction of the residues of amino
acid present in cellulase (composed of 344 amino acid) and silver ions which probably
when coordinated to groups having residues of amino acid such as -NH, -SH and
-OH groups were subsequently reduced by them. Meanwhile, Xie et al. (2007b)
reported that Au(III) or Ag(I) ions could be reduced by Tyr residues; thus, cellulase
containing 14 Tyr residues and other residues with reduction properties can also act as
a robust reducing agent. Moreover, Gholami-Shabani et al. (2014) utilized purified
nitrate reductase produced by Fusarium oxysporum for the biogenic synthesis of
AgNPs which used gelatin as a capping agent. The purified enzyme with a molecular
weight of 214 KDa as projected by gel filtration on Sephacryl S-300 biosynthesized
the AgNPs in a NADPH-dependent mode. The AgNPs synthesized were spherically
natured with an mean size of 50 nm and were studied for antimicrobial activities using
the disk-diffusion method which displayed strong growth inhibitory activity against
all tested human pathogenic bacteria and fungi as evident from inhibition zones that
ranged from 14 to 25 mm. Also, lignin peroxidase produced by Acinetobacter sp.
was purified via diethyl aminoethyl cellulose ion exchange, then by Biogel P-150 gel
filtration column chromatography and employed for the biogenic synthesis of AgNPs.
The purified lignin peroxidase which had molecular weight of 99 kDa and consisted
of dimers of two polypetides of 23.9 and 24.6 kDa as proven by native and SDS-PAGE
upon reduction of Ag ions was reported to produced spherical polydispersed AgNPs
of 50 nm in dimension as observed under TEM (Singh et al. 2017). Furthermore,
Mishra and Sardar (2012) reported the eco-friendly fabrication of AgNPs using pure
alpha-amylase obtained from Aspergillus oryzae. Results obtained displayed that the
AgNPs having a peak of 422 nm in UV–Vis spectrum was characterized by TEM to
be monodispersed, hexagonally and triangularly fashioned with sizes ranging from
22–44 nm. Deepak et al. (2011) reported that purified fibrinolytic enzyme (URAK)
generated by Bacillus cereus NK1 was employed for biosynthesizing AgNPs within
24 h which was significantly reduced to 5 min upon the addition of NaOH solution.
The AgNPs biosynthesized was reported to absorb maximally at 440 nm under the
UV–Vis spectrum. Also, the AgNPs were said to be crystalline, spherically shaped
with mean size of 60 nm.
2.5.2 Gold Nanoparticles (AuNPs)
El-Batal et al. (2015) described the synthesis of laccase generated by Pleurotus
ostreatus by means of SSF. The production was optimized using factorial design
and the laccase produced was partially purified, characterized and applied for the
biofabrication of AuNPs. The biosynthesis led to the development of a violet-colored