76
G. Grasso et al.
et al. 2011; Khan et al. 2018; Hulkoti and Taranath 2014). The biosynthesis of nanomaterials with defined dimension, morphology and composition, the mild physicochemical conditions required for biosynthetic process as well as the easily handling
and cultivation of microbial cells and possibility of cell culture scale-up are some of
the main advantages and features described in the literature for microbial-mediated
nanobiosynthesis.
In addition, some microorganisms have shown the capability to biosynthesize unique nanostructured materials, namely frustules, magnetosomes, nanocellulose, and nanowires. Frustules are periodic and hierarchical 3D-porous micronanostructures naturally biosynthesized by unicellular microalgae called ‘diatoms.’
Today, the ‘diatom nanotechnology’ is a rapidly evolving research field whose aims
to fully exploit the unique optical and optoelectronic properties of frustules and it is
also oriented to the development of new frustules-based functionalized nanostructures (Panwar and Dutta 2019). Bacterial magnetosomes are intracellular nanocrystals of Fe 3 O 4 and/or Fe 3 S 4 surrounded by an organic coating layer derived from the
bacterial phospholipid bilayer membrane. In particular, the bacterial Fe 3 O 4 magnetosomes possess several interesting features: They are permanently magnetic at ambient
temperature with a narrow size range and consistent crystal morphology (Yan et al.
2017).Bacterial nanocellulose is a 3D network of cellulose nanofibrils produced by
aerobic acetic bacteria like those belonging to the genus Gluconacetobacter. Bacterial nanocellulose is another unique nanomaterial of microbial origin that has recently
attracted great attention for biomedical applications (Sharma and Bhardwaj 2019).
Bacterial nanowires are conductive proteinaceous pilus-like nanostructures
involved in extracellular electron transport processes of anaerobic dissimilatory
metal-reducing bacteria belonging to Geobacter and Shewanella genera and present
in some aerobic bacteria like Pseudomonas aeruginosa and aerobic photosynthetic
cyanobacteria. Bacterial nanowires exhibit some interesting bioelectronic properties,
with high exploitation potential in the near future (Ilshadsabah and Suchithra 2019).
Both (bio)sensoristics and biomedical sectors would undoubtedly take advantages
for the development of broad-impact nanostructured-based technologies and applications (Dragone et al. 2017; Grasso et al. 2020; Prosa et al. 2020). However, the
reproducibility of nanosynthesis processes, the low cost-effectiveness ratio, limited
production yields and the inhomogeneity in the size and the shape of microbialsynthesized nanoparticles are just some of the hurdles that still need to be overcome
in order to enable a broad applicability of microbial-mediated nanobiosynthesis.
Interestingly, by changing some key parameters of cell culture operational set up
or through genetically engineering of selected microbial strains, a possible in vivo
tuning of size, morphology and composition of nanomaterial can be achieved, as
well as the enhancement in nanomaterials production yields. Thus, such microbiological and genetic strategies could represent concrete solutions for the problems currently encountered in microbial nanobiosynthesis as well as the opportunity
for future developments and promising uses of these fascinating materials. In this
chapter, we reported an overview of scientific literature about current main acquired
knowledge, challenges, and potentiality of microbial-mediated biosynthesis, with
particular reference to the isolation and screening of new microorganisms with
G. Grasso et al.
et al. 2011; Khan et al. 2018; Hulkoti and Taranath 2014). The biosynthesis of nanomaterials with defined dimension, morphology and composition, the mild physicochemical conditions required for biosynthetic process as well as the easily handling
and cultivation of microbial cells and possibility of cell culture scale-up are some of
the main advantages and features described in the literature for microbial-mediated
nanobiosynthesis.
In addition, some microorganisms have shown the capability to biosynthesize unique nanostructured materials, namely frustules, magnetosomes, nanocellulose, and nanowires. Frustules are periodic and hierarchical 3D-porous micronanostructures naturally biosynthesized by unicellular microalgae called ‘diatoms.’
Today, the ‘diatom nanotechnology’ is a rapidly evolving research field whose aims
to fully exploit the unique optical and optoelectronic properties of frustules and it is
also oriented to the development of new frustules-based functionalized nanostructures (Panwar and Dutta 2019). Bacterial magnetosomes are intracellular nanocrystals of Fe 3 O 4 and/or Fe 3 S 4 surrounded by an organic coating layer derived from the
bacterial phospholipid bilayer membrane. In particular, the bacterial Fe 3 O 4 magnetosomes possess several interesting features: They are permanently magnetic at ambient
temperature with a narrow size range and consistent crystal morphology (Yan et al.
2017).Bacterial nanocellulose is a 3D network of cellulose nanofibrils produced by
aerobic acetic bacteria like those belonging to the genus Gluconacetobacter. Bacterial nanocellulose is another unique nanomaterial of microbial origin that has recently
attracted great attention for biomedical applications (Sharma and Bhardwaj 2019).
Bacterial nanowires are conductive proteinaceous pilus-like nanostructures
involved in extracellular electron transport processes of anaerobic dissimilatory
metal-reducing bacteria belonging to Geobacter and Shewanella genera and present
in some aerobic bacteria like Pseudomonas aeruginosa and aerobic photosynthetic
cyanobacteria. Bacterial nanowires exhibit some interesting bioelectronic properties,
with high exploitation potential in the near future (Ilshadsabah and Suchithra 2019).
Both (bio)sensoristics and biomedical sectors would undoubtedly take advantages
for the development of broad-impact nanostructured-based technologies and applications (Dragone et al. 2017; Grasso et al. 2020; Prosa et al. 2020). However, the
reproducibility of nanosynthesis processes, the low cost-effectiveness ratio, limited
production yields and the inhomogeneity in the size and the shape of microbialsynthesized nanoparticles are just some of the hurdles that still need to be overcome
in order to enable a broad applicability of microbial-mediated nanobiosynthesis.
Interestingly, by changing some key parameters of cell culture operational set up
or through genetically engineering of selected microbial strains, a possible in vivo
tuning of size, morphology and composition of nanomaterial can be achieved, as
well as the enhancement in nanomaterials production yields. Thus, such microbiological and genetic strategies could represent concrete solutions for the problems currently encountered in microbial nanobiosynthesis as well as the opportunity
for future developments and promising uses of these fascinating materials. In this
chapter, we reported an overview of scientific literature about current main acquired
knowledge, challenges, and potentiality of microbial-mediated biosynthesis, with
particular reference to the isolation and screening of new microorganisms with