growth and enzymatic function (Nakajima and Shigeno 2014). Furthermore, biochemical reactions depend on the temperature of microbial activities, which having a
direct effect on cell physiology by altering proteins and permeability of the cell
membrane (Alberty 2006). Temperature and humidity were found to affect the
growth, biochemical activity, and reproduction of bacteria (Arbeli and Fuentes
2007; Parmar and Sindhu 2013). Bacteria usually degrade chlorpyrifos and
fenamiphos at temperature of 15–35
C, but its degradation potential was severely
reduced at low or high temperatures, i.e., 5 or 50
C (Singh et al. 2006). Siddique
et al. (2002) observed similar results during biodegradation of HCH isomers of soil
slurry. For α- and γ-HCH isomers, the incubation temperature of 30
C was found
optimum for degradation.
The surfactant can alter the solubility, absorption, and dehydration balance of
PAHs in soils and the interaction between PAHs and soil microorganisms, thereby
altering the bioavailability of PAHs. For example, Yuan et al. (2003) used a way to
reduce the interfacial tension between soil and water to increase the solubility of
PAHs, facilitated the transport of PAHs, and increased the bioavailability of PAHs.
However, due to the toxic effects of surfactants on microbes or the use of non-toxic
surfactants as a microbial growth matrix, the bioavailability of PAHs might be
inhibited. In addition, the effect of surfactants on the bioavailability of different
forms of PAHs in soils was found different, so that surfactant could be added to
increase the solubility of PAHs in the aqueous phase, to promote and improve the
solid phase transfer to the water phase and reduce the bioavailability and surface and
interfacial tension of the matrix (Yuan et al. 2003). Zhu et al. (2015) observed the
degradation and mineralization of biaryl compounds in soil and compost by bacteria
called Ralstonia and Pickettii and found that the nonionic surfactant Tween
80 increases bacterial utilization of biaryl compounds under appropriate soil moisture conditions, such as biphenyl, 4-chlorobiphenyl.
2.6 Removal of Pesticides Through Phytoremediation
Phytoremediation is a comprehensive strategy to isolate or detoxify environmental
pollutants and pesticides using plants and their associated microorganisms (Bhat and
Bhat 2016; Mitton et al. 2016). Plants are capable of degrading or removing metals,
pesticides, explosives, solvent, crude oil, and many industrial contaminants.
Phytoremediation is a clean, cost-effective, environmental-friendly technology, particularly for the treatment of large contaminated areas. It has been engaged in the
environmental cleaning industry (Macek et al. 2000; Suresh and Ravishankar 2004).
Various mechanisms involved in the phytoremediation process include:
(1) phytotransformation, which reduces toxicity, inactivates, or neutralizes contaminants caused by plant metabolism; (2) rhizodegradation which enhances the activity
of soil microorganisms to degrade contaminants by rhizosphere bacteria;
(3) phytoextraction, which absorbs contaminants from the polluted solids and stores
the substances in the plant biomass, with a potential to recover and reuse valuable
44
A. Sehrawat et al.
direct effect on cell physiology by altering proteins and permeability of the cell
membrane (Alberty 2006). Temperature and humidity were found to affect the
growth, biochemical activity, and reproduction of bacteria (Arbeli and Fuentes
2007; Parmar and Sindhu 2013). Bacteria usually degrade chlorpyrifos and
fenamiphos at temperature of 15–35
C, but its degradation potential was severely
reduced at low or high temperatures, i.e., 5 or 50
C (Singh et al. 2006). Siddique
et al. (2002) observed similar results during biodegradation of HCH isomers of soil
slurry. For α- and γ-HCH isomers, the incubation temperature of 30
C was found
optimum for degradation.
The surfactant can alter the solubility, absorption, and dehydration balance of
PAHs in soils and the interaction between PAHs and soil microorganisms, thereby
altering the bioavailability of PAHs. For example, Yuan et al. (2003) used a way to
reduce the interfacial tension between soil and water to increase the solubility of
PAHs, facilitated the transport of PAHs, and increased the bioavailability of PAHs.
However, due to the toxic effects of surfactants on microbes or the use of non-toxic
surfactants as a microbial growth matrix, the bioavailability of PAHs might be
inhibited. In addition, the effect of surfactants on the bioavailability of different
forms of PAHs in soils was found different, so that surfactant could be added to
increase the solubility of PAHs in the aqueous phase, to promote and improve the
solid phase transfer to the water phase and reduce the bioavailability and surface and
interfacial tension of the matrix (Yuan et al. 2003). Zhu et al. (2015) observed the
degradation and mineralization of biaryl compounds in soil and compost by bacteria
called Ralstonia and Pickettii and found that the nonionic surfactant Tween
80 increases bacterial utilization of biaryl compounds under appropriate soil moisture conditions, such as biphenyl, 4-chlorobiphenyl.
2.6 Removal of Pesticides Through Phytoremediation
Phytoremediation is a comprehensive strategy to isolate or detoxify environmental
pollutants and pesticides using plants and their associated microorganisms (Bhat and
Bhat 2016; Mitton et al. 2016). Plants are capable of degrading or removing metals,
pesticides, explosives, solvent, crude oil, and many industrial contaminants.
Phytoremediation is a clean, cost-effective, environmental-friendly technology, particularly for the treatment of large contaminated areas. It has been engaged in the
environmental cleaning industry (Macek et al. 2000; Suresh and Ravishankar 2004).
Various mechanisms involved in the phytoremediation process include:
(1) phytotransformation, which reduces toxicity, inactivates, or neutralizes contaminants caused by plant metabolism; (2) rhizodegradation which enhances the activity
of soil microorganisms to degrade contaminants by rhizosphere bacteria;
(3) phytoextraction, which absorbs contaminants from the polluted solids and stores
the substances in the plant biomass, with a potential to recover and reuse valuable
44
A. Sehrawat et al.