114
reduced the negative impact on microbial enzymatic activity in comparison to pristine ceria nanoparticles (Hamidat et al. 2016).
4.6 Effect on Water Microbial Flora
The use of nanoparticle-based consumer products and their release in water bodies
is also increasing their concentration in water bodies. The nanoparticles also affect
the microbial community structure and microbial physiology in water bodies. The
effect of nanoparticles on freshwater bacteria in three Swedish lakes was studied by
Farkas et al. (2015). They found reduction at 1000 ppm concentration in the abundance of freshwater bacteria. The activity of nanoparticles in water also depends on
the pH, dissolved titanium oxide organic matter, and ionic strength, and also influences particle stability (Christian et al. 2008, Keller et al. 2010, Ottofuelling et al.
2011). Qiu et al. (2016) also revealed toxicity of titanium oxide nanoparticles on
bacterial community in wastewater system but overall biodiversity was remained
unchanged. They found that production of extra polymer substance prevents the
toxic effect of titanium oxide nanoparticles by removal and deposition as sludge
from the system. Further, Hou et al. (2012) and (2013) reported that zinc oxide and
silver nanoparticles in wastewater inhibited the nitrifying bacteria Rhodomicrobium,
Pseudomonas, and í µí»¿-Proteobacteria species by reducing their respiration. Das et al.
(2012) also reported the effect of carboxy functionalized silver (Ag) nanoparticles
on natural water microbial community and found significant change in bacterial
community and reduced bacterial biomass. The citrate and Gum Arabic-coated Ag
nanoparticles reduced the chemical oxygen demand and ammonia removal efficiency in wastewater microbial communities at 0.2–2 ppm. The decrease of microbial diversity was also assessed by Alito and Gunsch (2014). Further, Puay et al.
(2015) showed that toxicity of copper oxide nanoparticles in microbial communities
of wastewater. In contrast, on exposure of nanomaterial some microbes produce
extracellular polymers which reduce the toxicity by chelating metal nanoparticles.
4.7 Mechanism of Nanomaterial Toxicity
to Microbial Community
The toxicity of nanoparticles to microorganism is found via different mode of
actions such as formation of reactive oxygen species (ROS), interruption of energy
transduction, disruption of ionic channels, and inhibition of enzyme activity (Xia
et al. 2008). Mainly toxicity depends on the dissolution of nanomaterial. The dissolution of nanomaterial also affected with the different environmental factors such
as pH, temperature, presence of organic matter, as well as physiochemical properties of material such as size, shape, surface area, and chemical composition. It has
H. Chhipa
reduced the negative impact on microbial enzymatic activity in comparison to pristine ceria nanoparticles (Hamidat et al. 2016).
4.6 Effect on Water Microbial Flora
The use of nanoparticle-based consumer products and their release in water bodies
is also increasing their concentration in water bodies. The nanoparticles also affect
the microbial community structure and microbial physiology in water bodies. The
effect of nanoparticles on freshwater bacteria in three Swedish lakes was studied by
Farkas et al. (2015). They found reduction at 1000 ppm concentration in the abundance of freshwater bacteria. The activity of nanoparticles in water also depends on
the pH, dissolved titanium oxide organic matter, and ionic strength, and also influences particle stability (Christian et al. 2008, Keller et al. 2010, Ottofuelling et al.
2011). Qiu et al. (2016) also revealed toxicity of titanium oxide nanoparticles on
bacterial community in wastewater system but overall biodiversity was remained
unchanged. They found that production of extra polymer substance prevents the
toxic effect of titanium oxide nanoparticles by removal and deposition as sludge
from the system. Further, Hou et al. (2012) and (2013) reported that zinc oxide and
silver nanoparticles in wastewater inhibited the nitrifying bacteria Rhodomicrobium,
Pseudomonas, and í µí»¿-Proteobacteria species by reducing their respiration. Das et al.
(2012) also reported the effect of carboxy functionalized silver (Ag) nanoparticles
on natural water microbial community and found significant change in bacterial
community and reduced bacterial biomass. The citrate and Gum Arabic-coated Ag
nanoparticles reduced the chemical oxygen demand and ammonia removal efficiency in wastewater microbial communities at 0.2–2 ppm. The decrease of microbial diversity was also assessed by Alito and Gunsch (2014). Further, Puay et al.
(2015) showed that toxicity of copper oxide nanoparticles in microbial communities
of wastewater. In contrast, on exposure of nanomaterial some microbes produce
extracellular polymers which reduce the toxicity by chelating metal nanoparticles.
4.7 Mechanism of Nanomaterial Toxicity
to Microbial Community
The toxicity of nanoparticles to microorganism is found via different mode of
actions such as formation of reactive oxygen species (ROS), interruption of energy
transduction, disruption of ionic channels, and inhibition of enzyme activity (Xia
et al. 2008). Mainly toxicity depends on the dissolution of nanomaterial. The dissolution of nanomaterial also affected with the different environmental factors such
as pH, temperature, presence of organic matter, as well as physiochemical properties of material such as size, shape, surface area, and chemical composition. It has
H. Chhipa