systems established the NPs effects onto the implementation
of arbuscular mycorrhizal fungi (AMF), nitrogen fixation,
and on the fabrication of microbial siderophores in the plant
rhizosphere. Hence, it might be recommended that, for a
better understanding of the agro-ecological NPs implications, would necessitate additional exhaustive interactive
studies in collective plant /microbes/nanoparticles system
(Dimkpa 2014).
Regarding the microbes in soil, the comprehensible and
metal NPs specific effect was observed on microflora in the
soil. For instance, the TiO 2 NPs showed an impact on
symbiosis of Rhizobium-legume in garden peas and Rhizobium (R. leguminosarum bv. vivae 3841). It was also found
that TiO 2 NPs put forth morphological modifications in the
cells of bacteria. Moreover, Fan et al. (2014) also reported
that whenever there the interaction between these two
organisms takes place, they disturbed the formation of root
nodules and the succeeding postponement in the nitrogen
fixation commencement. The immediate application of NPs
keen on treated biosolids or soils having transportable NPs
might interact with the microbes in the soil. These soil
microbes are also competent towards the adsorption and
accumulation in one or the other form of NMs that in turn
begins the NMs mobilization and is capable to alter communities encompassing the populations of plants, animals
and finally humans through the food chains (Holden et al.
2013; Ranjan et al. 2014; Thul and Sarangi 2015).
Conversely, plants, in general, get mineral nutrients from
the soils with the help of the soil bacteria and fungi. A study
discovered that the AgNPs, which are a popular microbicidal
agent, negatively impact the plants growth and eradicates the
microbes in the soil that maintain them. Not just microorganisms, but the several soil enzymes activity, e.g. soil
peroxidase, catalase, as well as protease, was established to
considerably diminished by TiO 2 NPs (Du et al. 2011).
Furthermore, inorganic TiO 2 , SiO 2 as well as ZnO had found
to put forth a lethal effect on bacteria. In the presence of
light, the toxicity of these elements further significantly
increased (Adams et al. 2006). There are the variety of
reports that have been spotted light upon the interactions
between NPs-microbe’s for associating the ENPs (metal and
metal oxides) physicochemical properties and their responses in the biological systems. Additionally, in conclusion,
the species-specific toxicity of NPs could be attributed to its
shape and size. Research on the ecologically significant
species of bacteria, e.g. Bacillus subtilis, Escherichia coli,
Pseudomonas putida and other, has noticeably indicated
microorganisms be able to take up NPs (Thul and Sarangi
2015; Załęska-Radziwiłł and Doskocz 2015).
In the terrestrial and aquatic ecosystems, bacteria are
essential elements as they act as decomposers of organic
matter as well as key bases for numerous webs of foods
(Thul et al. 2013). Because the dependency of plants on the
fungi and bacteria present in soil and air to get their nutrients, the antimicrobial and cellular toxicity effects of NPs for
instance, Ag, TiO 2 and Au NPs and nano-emulsions as well
might show the effect on the environment (Thul et al. 2013;
Dasgupta 2016b, c; Jain et al. 2016; Maddineni et al. 2015;
Ranjan et al. 2016). Hajipour et al. (2012) have examined
the NPs for their antibacterial properties in a very illustrative
manner. It has also been demonstrated that soil microbes,
that are plentiful and flexible catalysts, are capable to adsorb
and disband the aggregates of ENPs (Horst et al. 2010). It
has been reported that the addition of nanoscale zerovalent
iron leads to perturbation in soil bacterial community composition, as well as condensed the chloroaromatic mineralizing activity of microbes (Tilston et al. 2013).
4.2 Interaction of Engineered Nanoparticles
with Soil Microbiota
The ENPs were also established to considerably modify the
bacterial communities in a dose-dependent approach, and
NPs are known to influence the dynamics of the microbial
community (Ge et al. 2011). In order to this, Priester et al.
(2012) reported the uptake of ENPs of CeO 2 into the soybean roots and root nodules, which reduced the nitrogen
fixation potentials along with the damaged growth of crop
plants (Priester et al. 2012). Further studies about the beneficial soil microbes, such as nitrogen fixers, AM fungi,
phosphate solubilizers, have demonstrated the uptake
mechanisms of the NPs as well as the significance to accumulate in the soil and microorganisms (Ge et al. 2011; Thul
et al. 2013). The ENPs mobility in soils is totally dependent
on their size, though that is the agglomerates size, not the
primary size that is concerned with the transportability of
them. There are several aspects, those organize the transfer
of these ENPs in the soils; however, charge, size and the rate
of agglomeration in the transport medium are prognostic of
the mobility of these ENPs in the soils. The metal NPs
survival as well as speciation in the soil solution and the
understanding on interaction among soil solution or other
ions and their active sites is significant for getting a better
knowledge about the interactions between metal NPs and
soil microbes. Nevertheless, the solution chemistry of metal
NPs is somewhat restricted, and thermodynamic data like
reaction constants and solubility of NPs are not available. In
addition to this, the additional data is requisite to distinguish
the effect of ENPs on the soil microbial community in a
variety of soils having different physicochemical features
and soils from the diverse ecosystem (Dinesh et al. 2012).
In conclusion, a number of novel ENPs from both environmental and industrial applications and resulting from
various activities of human as by-products, act as xenobiotics and find their own way to enter into the soil. Thus, the
182
S. S. Shende et al.
of arbuscular mycorrhizal fungi (AMF), nitrogen fixation,
and on the fabrication of microbial siderophores in the plant
rhizosphere. Hence, it might be recommended that, for a
better understanding of the agro-ecological NPs implications, would necessitate additional exhaustive interactive
studies in collective plant /microbes/nanoparticles system
(Dimkpa 2014).
Regarding the microbes in soil, the comprehensible and
metal NPs specific effect was observed on microflora in the
soil. For instance, the TiO 2 NPs showed an impact on
symbiosis of Rhizobium-legume in garden peas and Rhizobium (R. leguminosarum bv. vivae 3841). It was also found
that TiO 2 NPs put forth morphological modifications in the
cells of bacteria. Moreover, Fan et al. (2014) also reported
that whenever there the interaction between these two
organisms takes place, they disturbed the formation of root
nodules and the succeeding postponement in the nitrogen
fixation commencement. The immediate application of NPs
keen on treated biosolids or soils having transportable NPs
might interact with the microbes in the soil. These soil
microbes are also competent towards the adsorption and
accumulation in one or the other form of NMs that in turn
begins the NMs mobilization and is capable to alter communities encompassing the populations of plants, animals
and finally humans through the food chains (Holden et al.
2013; Ranjan et al. 2014; Thul and Sarangi 2015).
Conversely, plants, in general, get mineral nutrients from
the soils with the help of the soil bacteria and fungi. A study
discovered that the AgNPs, which are a popular microbicidal
agent, negatively impact the plants growth and eradicates the
microbes in the soil that maintain them. Not just microorganisms, but the several soil enzymes activity, e.g. soil
peroxidase, catalase, as well as protease, was established to
considerably diminished by TiO 2 NPs (Du et al. 2011).
Furthermore, inorganic TiO 2 , SiO 2 as well as ZnO had found
to put forth a lethal effect on bacteria. In the presence of
light, the toxicity of these elements further significantly
increased (Adams et al. 2006). There are the variety of
reports that have been spotted light upon the interactions
between NPs-microbe’s for associating the ENPs (metal and
metal oxides) physicochemical properties and their responses in the biological systems. Additionally, in conclusion,
the species-specific toxicity of NPs could be attributed to its
shape and size. Research on the ecologically significant
species of bacteria, e.g. Bacillus subtilis, Escherichia coli,
Pseudomonas putida and other, has noticeably indicated
microorganisms be able to take up NPs (Thul and Sarangi
2015; Załęska-Radziwiłł and Doskocz 2015).
In the terrestrial and aquatic ecosystems, bacteria are
essential elements as they act as decomposers of organic
matter as well as key bases for numerous webs of foods
(Thul et al. 2013). Because the dependency of plants on the
fungi and bacteria present in soil and air to get their nutrients, the antimicrobial and cellular toxicity effects of NPs for
instance, Ag, TiO 2 and Au NPs and nano-emulsions as well
might show the effect on the environment (Thul et al. 2013;
Dasgupta 2016b, c; Jain et al. 2016; Maddineni et al. 2015;
Ranjan et al. 2016). Hajipour et al. (2012) have examined
the NPs for their antibacterial properties in a very illustrative
manner. It has also been demonstrated that soil microbes,
that are plentiful and flexible catalysts, are capable to adsorb
and disband the aggregates of ENPs (Horst et al. 2010). It
has been reported that the addition of nanoscale zerovalent
iron leads to perturbation in soil bacterial community composition, as well as condensed the chloroaromatic mineralizing activity of microbes (Tilston et al. 2013).
4.2 Interaction of Engineered Nanoparticles
with Soil Microbiota
The ENPs were also established to considerably modify the
bacterial communities in a dose-dependent approach, and
NPs are known to influence the dynamics of the microbial
community (Ge et al. 2011). In order to this, Priester et al.
(2012) reported the uptake of ENPs of CeO 2 into the soybean roots and root nodules, which reduced the nitrogen
fixation potentials along with the damaged growth of crop
plants (Priester et al. 2012). Further studies about the beneficial soil microbes, such as nitrogen fixers, AM fungi,
phosphate solubilizers, have demonstrated the uptake
mechanisms of the NPs as well as the significance to accumulate in the soil and microorganisms (Ge et al. 2011; Thul
et al. 2013). The ENPs mobility in soils is totally dependent
on their size, though that is the agglomerates size, not the
primary size that is concerned with the transportability of
them. There are several aspects, those organize the transfer
of these ENPs in the soils; however, charge, size and the rate
of agglomeration in the transport medium are prognostic of
the mobility of these ENPs in the soils. The metal NPs
survival as well as speciation in the soil solution and the
understanding on interaction among soil solution or other
ions and their active sites is significant for getting a better
knowledge about the interactions between metal NPs and
soil microbes. Nevertheless, the solution chemistry of metal
NPs is somewhat restricted, and thermodynamic data like
reaction constants and solubility of NPs are not available. In
addition to this, the additional data is requisite to distinguish
the effect of ENPs on the soil microbial community in a
variety of soils having different physicochemical features
and soils from the diverse ecosystem (Dinesh et al. 2012).
In conclusion, a number of novel ENPs from both environmental and industrial applications and resulting from
various activities of human as by-products, act as xenobiotics and find their own way to enter into the soil. Thus, the
182
S. S. Shende et al.