84
G. Grasso et al.
Konishi et al. (2007) have also described the importance of pH as controlling
factor over the morphology of AuNPs and the cellular site of Au deposition in the
bacterium Shewanella algae ATCC 51181. Gericke and Pinches (2006) have reported
that variations in pH could affect in a very peculiar way the size, shape and number of
AuNPs produced by the fungus Verticillium luteoalbum DSM 63545. In particular,
changes in the pH value from 3 to 9 have produced: (i) a greater heterogeneity in
NPs size (ii) a decrease numbers of NPs produced per cell and (iii) a greater heterogeneity in shape. In particular, the spherical shape has been predominant at pH 3,
while triangular-, hexagonal-, spherical-, and rod-shaped NPs have been produced at
pH 5 NPs and small spherical NPs and bigger NPs with irregular, undefined shapes
have been observed at pH 7 and 9. These results have suggested that pH would play an
important role in the tuning of nanoparticles morphology produced by V. luteoalbum
DSM 63545. The variation of temperature seemed to exert a similar tuning effect on
the morphology of AgNPs synthesized by Morganella psychrotolerans (Ramanathan
et al. (2011). These results have shown that small spherical-shaped AgNPs were
produced at 20 °C, the optimal temperature for the growth and physiological activities of M. psychrotolerans, while triangular and hexagonal nanoplates along with
spherical nanoparticles have been observed at 5 °C above and below 20 °C. At 4 °C,
the number of nanoplates was greater than the number of spherical NPs, but larger
compared to those obtained at 20 °C. Other recent examples include the temperature
dependence of size and monodispersity observed in AgNPs biosynthesis by mold
Trichoderma viride (Mohammed Fayaz et al. 2009) and the effect of temperature on
the release of Au nanostructures from the yeast Yarrowia lipolytica NCIM 3589 cell
wall into the aqueous phase. Changes in type and size of Au nanostructures have
been also observed though modification in the proportion of cell concentration and
in the concentration of the precursor gold salt (Pimprikar et al. 2009).
The photoautotrophic metabolism of microalgae and cyanobacteria is based on
carbon dioxide (as carbon source), light (as energy source), inorganic nutrients,
and water. This condition generally reduces the costs of culture media (compared
to the costs for culture media used for the growth of bacteria, yeasts, and molds)
thus promoting the future scaling-up from the laboratory to the industrial scale, also
through the design and the development of atmospheric CO 2 mitigation microbialbased technologies. One example has been provided by a recent study, where a
potentiation in AgNPs biosynthesis has been observed for high CO 2 acclimated
strain green algae Desmodesmus abundans and Spirulina platensis (Mora-Godínez
et al. 2020). The effects of light on the ability to produce nanoparticles have been
also reported in the literature for photosynthetic microorganisms like cyanobacteria
and green algae. For instance, the influence of light/dark condition on the AgNPs
biosynthesis by different selected cyanobacterial and green algae strains has been
investigated by Patel et al. (2015).
Among abiotic parameters, intensity and spectral characteristics of light play
a primary role for diatoms cultivation and can strongly influence frustule characteristics. Su et al. (2015) have found that in Coscinodiscus granii, the use of red,
G. Grasso et al.
Konishi et al. (2007) have also described the importance of pH as controlling
factor over the morphology of AuNPs and the cellular site of Au deposition in the
bacterium Shewanella algae ATCC 51181. Gericke and Pinches (2006) have reported
that variations in pH could affect in a very peculiar way the size, shape and number of
AuNPs produced by the fungus Verticillium luteoalbum DSM 63545. In particular,
changes in the pH value from 3 to 9 have produced: (i) a greater heterogeneity in
NPs size (ii) a decrease numbers of NPs produced per cell and (iii) a greater heterogeneity in shape. In particular, the spherical shape has been predominant at pH 3,
while triangular-, hexagonal-, spherical-, and rod-shaped NPs have been produced at
pH 5 NPs and small spherical NPs and bigger NPs with irregular, undefined shapes
have been observed at pH 7 and 9. These results have suggested that pH would play an
important role in the tuning of nanoparticles morphology produced by V. luteoalbum
DSM 63545. The variation of temperature seemed to exert a similar tuning effect on
the morphology of AgNPs synthesized by Morganella psychrotolerans (Ramanathan
et al. (2011). These results have shown that small spherical-shaped AgNPs were
produced at 20 °C, the optimal temperature for the growth and physiological activities of M. psychrotolerans, while triangular and hexagonal nanoplates along with
spherical nanoparticles have been observed at 5 °C above and below 20 °C. At 4 °C,
the number of nanoplates was greater than the number of spherical NPs, but larger
compared to those obtained at 20 °C. Other recent examples include the temperature
dependence of size and monodispersity observed in AgNPs biosynthesis by mold
Trichoderma viride (Mohammed Fayaz et al. 2009) and the effect of temperature on
the release of Au nanostructures from the yeast Yarrowia lipolytica NCIM 3589 cell
wall into the aqueous phase. Changes in type and size of Au nanostructures have
been also observed though modification in the proportion of cell concentration and
in the concentration of the precursor gold salt (Pimprikar et al. 2009).
The photoautotrophic metabolism of microalgae and cyanobacteria is based on
carbon dioxide (as carbon source), light (as energy source), inorganic nutrients,
and water. This condition generally reduces the costs of culture media (compared
to the costs for culture media used for the growth of bacteria, yeasts, and molds)
thus promoting the future scaling-up from the laboratory to the industrial scale, also
through the design and the development of atmospheric CO 2 mitigation microbialbased technologies. One example has been provided by a recent study, where a
potentiation in AgNPs biosynthesis has been observed for high CO 2 acclimated
strain green algae Desmodesmus abundans and Spirulina platensis (Mora-Godínez
et al. 2020). The effects of light on the ability to produce nanoparticles have been
also reported in the literature for photosynthetic microorganisms like cyanobacteria
and green algae. For instance, the influence of light/dark condition on the AgNPs
biosynthesis by different selected cyanobacterial and green algae strains has been
investigated by Patel et al. (2015).
Among abiotic parameters, intensity and spectral characteristics of light play
a primary role for diatoms cultivation and can strongly influence frustule characteristics. Su et al. (2015) have found that in Coscinodiscus granii, the use of red,