Precision Microbial Nanobiosynthesis: Knowledge …
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AgNPs synthesis in the microalga Neochloris oleoabundans has been demonstrated
(Bao and Lan 2018). Another study has highlighted the active role of xanthophyll
pigment fucoxanthin as photo-reducing agent for AgNPs formation through lightdependent reactions in diatom Amphora-46 (Jena et al. 2015). In cyanobacteria, the
involvement in nanoparticles synthesis has been ascribed to several biochemical
entities including polysaccharides, pigments, phytochelatins, NADPH-dependent
reductase and nitrogen-fixing enzyme nitrogenase (Pathak et al. 2018). In bacteria
belonging to the genus Bacillus, one of the most studied and promising bacterial genus
for industrial application, two recent studies have confirmed the role of enzymes in
the synthesis of AgNPs. Mukherjee et al. (2018) have adopted in silico approaches
to profile the NADPH-dependent nitrate reductase enzyme involved in AgNPs using
Bacillus clausii. The presence of reducing and capping agents in AgNPs biosynthesized by Bacillus subtilis spizizenii NCIM-2063 has been confirmed. The list of these
reducing and capping agents include enzymes nitrate reductase, endo-alpha-(1->5)-larabinanase, cyclic-di-AMP phosphodiesterase NADPH dehydrogenase (Sable et al.
2020).
The bacterial genus Pseudomonas has been also widely studied for the production
of primary and secondary metabolites for broader range of possible applications
such as industrial, medical, and environmental with promising uses in microbial
nanobiosynthesis. The intracellular ability to assembly and to extracellular release
SeNPs has been studied in the bacterium S. maltophilia SeITE02. This bacterium has
demonstrated a 100% reduction ability of 0.5 mM SeO 3
2− within 48 h growth. The
involvement of cytoplasmic thiol containing molecules and/or peptides/proteins in
the reduction of SeO 3
2− to Se
0 as well as the possible involvement of the identified
alcohol dehydrogenase homolog in the extracellular SeNPs biogenesis process have
been described (Lampis et al. 2017). The importance of glutathione reductase and
reduced glutathione has been highlighted in Pseudomonas stutzeri TS44 for the
formation of SeNPs CdSe QDs, respectively (Wang et al. 2019). Some capping
agents in AgNPs biosynthesized by P. aeruginosa ATCC 27853 have been identified
(Quinteros et al. 2019). Among the identified proteins, the involvement in AgNPs
formation has been suggested for alkyl hydroperoxide reductase and azurin, while
the role of stabilizing agent has been suggested for outer membrane protein OprG
and glycine zipper 2 TM domain-containing protein.
Still on bacteria, under anaerobic conditions, dissimilatory metal-reducing
bacteria display a remarkable respiratory versatility in the number of terminal electron acceptors, including insoluble metal electron acceptors. Such ability is largely
due to the multihaeme c-type cytochromes in the respiratory electron transfer chain.
The importance of the outer membrane decaheme cytochrome MtrC in extracellular synthesis UO 2 nanoparticles by the dissimilatory metal-reducing bacterium S.
oneidensis MR-1 has been reported (Marshall et al. 2006). Vasylevskyi et al. (2017)
have also described the role of the c-cytochromes of the electron transfer chain as
biocatalytic component involved in AgNPs biosynthesis by the dissimilatory metalreducing bacteria G. sulfurreducens. Recently, the involvement of extracellular electron transport pathway has been also revealed in photo-driven AuNPs biosynthesis
by S. oneidensis MR-1 (Huang et al. 2019).
89
AgNPs synthesis in the microalga Neochloris oleoabundans has been demonstrated
(Bao and Lan 2018). Another study has highlighted the active role of xanthophyll
pigment fucoxanthin as photo-reducing agent for AgNPs formation through lightdependent reactions in diatom Amphora-46 (Jena et al. 2015). In cyanobacteria, the
involvement in nanoparticles synthesis has been ascribed to several biochemical
entities including polysaccharides, pigments, phytochelatins, NADPH-dependent
reductase and nitrogen-fixing enzyme nitrogenase (Pathak et al. 2018). In bacteria
belonging to the genus Bacillus, one of the most studied and promising bacterial genus
for industrial application, two recent studies have confirmed the role of enzymes in
the synthesis of AgNPs. Mukherjee et al. (2018) have adopted in silico approaches
to profile the NADPH-dependent nitrate reductase enzyme involved in AgNPs using
Bacillus clausii. The presence of reducing and capping agents in AgNPs biosynthesized by Bacillus subtilis spizizenii NCIM-2063 has been confirmed. The list of these
reducing and capping agents include enzymes nitrate reductase, endo-alpha-(1->5)-larabinanase, cyclic-di-AMP phosphodiesterase NADPH dehydrogenase (Sable et al.
2020).
The bacterial genus Pseudomonas has been also widely studied for the production
of primary and secondary metabolites for broader range of possible applications
such as industrial, medical, and environmental with promising uses in microbial
nanobiosynthesis. The intracellular ability to assembly and to extracellular release
SeNPs has been studied in the bacterium S. maltophilia SeITE02. This bacterium has
demonstrated a 100% reduction ability of 0.5 mM SeO 3
2− within 48 h growth. The
involvement of cytoplasmic thiol containing molecules and/or peptides/proteins in
the reduction of SeO 3
2− to Se
0 as well as the possible involvement of the identified
alcohol dehydrogenase homolog in the extracellular SeNPs biogenesis process have
been described (Lampis et al. 2017). The importance of glutathione reductase and
reduced glutathione has been highlighted in Pseudomonas stutzeri TS44 for the
formation of SeNPs CdSe QDs, respectively (Wang et al. 2019). Some capping
agents in AgNPs biosynthesized by P. aeruginosa ATCC 27853 have been identified
(Quinteros et al. 2019). Among the identified proteins, the involvement in AgNPs
formation has been suggested for alkyl hydroperoxide reductase and azurin, while
the role of stabilizing agent has been suggested for outer membrane protein OprG
and glycine zipper 2 TM domain-containing protein.
Still on bacteria, under anaerobic conditions, dissimilatory metal-reducing
bacteria display a remarkable respiratory versatility in the number of terminal electron acceptors, including insoluble metal electron acceptors. Such ability is largely
due to the multihaeme c-type cytochromes in the respiratory electron transfer chain.
The importance of the outer membrane decaheme cytochrome MtrC in extracellular synthesis UO 2 nanoparticles by the dissimilatory metal-reducing bacterium S.
oneidensis MR-1 has been reported (Marshall et al. 2006). Vasylevskyi et al. (2017)
have also described the role of the c-cytochromes of the electron transfer chain as
biocatalytic component involved in AgNPs biosynthesis by the dissimilatory metalreducing bacteria G. sulfurreducens. Recently, the involvement of extracellular electron transport pathway has been also revealed in photo-driven AuNPs biosynthesis
by S. oneidensis MR-1 (Huang et al. 2019).