103
such as bacteria, fungi, nematode, protozoa, and arthropods, which play a significant role in the sustainable food chain of the local ecosystem.
The increasing number of nanomaterial-based consumer products enhances the
amount of nanomaterials in soil. The accumulated nanomaterials, interacted with
different soil microbes and affected their activities (Table 4.1). The interaction of
different nanomaterials with different soil microbial communities influences microbial flora in both ways. Some nanomaterials induce the abundance of soil microbes
and some destroy the community structure. The positive and negative impact of
nanomaterial on microbial flora depends on the concentration and dissolution rate
of nanomaterials present in the soil.
Johansen et al. (2008) reported that carbon nanomaterial does not influence the
soil microbial community and it can be a potential tool for environmental application, but they found a little change in the number of fast-growing bacteria. Reduction
in the number of fast-growing bacteria affected the protozoan community because
they feed on the bacteria. The chemical nature of nanoparticles also plays a significant role in their toxic nature. Moll et al. (2016) reported that multi-walled carbon
nanomaterial more influenced the symbiotic microbial activity in comparison to
titanium oxide and cerium oxide nanoparticles. The toxicity of nanoparticles on
monoculture was found due to disorganization of cellular membrane, DNA damage,
generation of reactive oxygen species, and photocatalytic oxidation of nanoparticles. In soil, nanoparticles activity was affected by agglomeration, adsorption,
desorption, dissolution, and migration by different soil properties like pH, ionic
strength, clay content, soil moisture, and organic matter content. The above-reported
factors changed the concentration of nanomaterials and showed variability in terms
of toxicity toward microbial community (Brayner et al. 2006; Choi and Hu 2008;
Gou et al. 2010).
The toxicity of nanoparticle in soil depends on the dose and soil type. In some
cases, low dose showed enhancement of microbial biomass while in contrast some
cases reduction in microbial biomass measured (Pan and Xing 2012). Wu et al.
(2010) reported that metal nanoparticle can be aggregated and formed large agglomerate which reduce the nanoparticle toxicity.
Soil pH is one of the important parameters, which influences the toxicity of the
nanomaterial by playing a significant role in their dissolution, mobility, and migration to soil microbial community and plants (Heggelund et al. 2014, WaalewijnKool et al. 2013). Schlich and Hund-Rinke (2015) studied the effect of soil types on
nano-toxicity to microorganism and found that in acidic soil, silver nanoparticle
toxicity was more in comparison to alkaline soil. They observed that soil pH influences the release of ions via dissolution of metals. Previously, Waalewijn-Kool et al.
(2013) also found zinc oxide toxicity in their study and stated that metallic nanoparticle toxicity was dependent on soil pH and soil acidity increased the toxicity.
The concentration of nanoparticles and exposure time also affect the toxicity.
Collins et al. (2012) measured no significant change in the community structure of
Rhizobiales at 550 mg by copper and zinc oxide nanoparticles after 160 days of
exposure in culture-independent FAME analysis. But they found little change in
order Flavobacteriales due to copper nanoparticles. They suggested that microbial
4 Nano-toxicity to Microbes: Potential Implications of Nanomaterials on Microbial…
such as bacteria, fungi, nematode, protozoa, and arthropods, which play a significant role in the sustainable food chain of the local ecosystem.
The increasing number of nanomaterial-based consumer products enhances the
amount of nanomaterials in soil. The accumulated nanomaterials, interacted with
different soil microbes and affected their activities (Table 4.1). The interaction of
different nanomaterials with different soil microbial communities influences microbial flora in both ways. Some nanomaterials induce the abundance of soil microbes
and some destroy the community structure. The positive and negative impact of
nanomaterial on microbial flora depends on the concentration and dissolution rate
of nanomaterials present in the soil.
Johansen et al. (2008) reported that carbon nanomaterial does not influence the
soil microbial community and it can be a potential tool for environmental application, but they found a little change in the number of fast-growing bacteria. Reduction
in the number of fast-growing bacteria affected the protozoan community because
they feed on the bacteria. The chemical nature of nanoparticles also plays a significant role in their toxic nature. Moll et al. (2016) reported that multi-walled carbon
nanomaterial more influenced the symbiotic microbial activity in comparison to
titanium oxide and cerium oxide nanoparticles. The toxicity of nanoparticles on
monoculture was found due to disorganization of cellular membrane, DNA damage,
generation of reactive oxygen species, and photocatalytic oxidation of nanoparticles. In soil, nanoparticles activity was affected by agglomeration, adsorption,
desorption, dissolution, and migration by different soil properties like pH, ionic
strength, clay content, soil moisture, and organic matter content. The above-reported
factors changed the concentration of nanomaterials and showed variability in terms
of toxicity toward microbial community (Brayner et al. 2006; Choi and Hu 2008;
Gou et al. 2010).
The toxicity of nanoparticle in soil depends on the dose and soil type. In some
cases, low dose showed enhancement of microbial biomass while in contrast some
cases reduction in microbial biomass measured (Pan and Xing 2012). Wu et al.
(2010) reported that metal nanoparticle can be aggregated and formed large agglomerate which reduce the nanoparticle toxicity.
Soil pH is one of the important parameters, which influences the toxicity of the
nanomaterial by playing a significant role in their dissolution, mobility, and migration to soil microbial community and plants (Heggelund et al. 2014, WaalewijnKool et al. 2013). Schlich and Hund-Rinke (2015) studied the effect of soil types on
nano-toxicity to microorganism and found that in acidic soil, silver nanoparticle
toxicity was more in comparison to alkaline soil. They observed that soil pH influences the release of ions via dissolution of metals. Previously, Waalewijn-Kool et al.
(2013) also found zinc oxide toxicity in their study and stated that metallic nanoparticle toxicity was dependent on soil pH and soil acidity increased the toxicity.
The concentration of nanoparticles and exposure time also affect the toxicity.
Collins et al. (2012) measured no significant change in the community structure of
Rhizobiales at 550 mg by copper and zinc oxide nanoparticles after 160 days of
exposure in culture-independent FAME analysis. But they found little change in
order Flavobacteriales due to copper nanoparticles. They suggested that microbial
4 Nano-toxicity to Microbes: Potential Implications of Nanomaterials on Microbial…