environment (Valls et al. 2000; Ackerley et al. 2004; Kube et al. 2005; Parnell et al.
2006; Schue et al. 2009; Liu et al. 2011).
Moreover, the genetic engineering of plants also performed to enhance the
accumulation and tolerance capacity as well as detoxification potential for heavy
metal pollutants and to increase the biomass and growth of plants in metal contaminated sites (Hassani 2014). Metallothioneins (MTs) are the unique cysteine-rich
peptides that are relevant to higher metal-binding capacity in hyperaccumulating
plants and have been cloned to develop the genetically engineered plants for
phytoremediation of organic and inorganic pollutants. Tobacco plant was the first
genetically engineered plant for the phytoremediation of explosives and halogenated
organic pollutants (Doty et al. 2000). Many reports have been published on the
genetic engineering of plants and their role in the phytoremediation of contaminated
soil and water environment (Cherian and Oliveira 2005; Pilon-Smits 2005; Eapen
et al. 2007; Doty 2008; Macek et al. 2008; James and Strand 2009; Kawahigashi
2009; Van 2009). Recently, James and Strand (2009) reported the dehalogenation of
tetrachloroethylene (PCE) by hybrid poplar trees under controlled field conditions.
Genetically modified organisms can be also used as biosensors for related mixures of
agrochemicals, petroleum products, metals, and toxins that are found in the environment, but cannot be directly in soil or water (Ozcan et al. 2011).
3 Environmental Bioremediation Technologies
Environmental bioremediation technologies broadly can be classified into two major
categories: bioremediation and phytoremediation.
3.1 Bioremediation
Bioremediation is the eco-friendly technique wherein biological agents (microbes
and plants or their enzymes) are used to degrade and detoxify the organic and
inorganic pollutants to safeguard the environment and public health in low-cost
and efficient manner (Azubuike et al. 2016; Bharagava et al. 2018; Kishor et al.
2018). A range of bioremediation techniques have been developed by researchers to
date; but due to diverse characteristics of pollutants and merits and demerits, no
single bioremediation technique can provide full-scale solution to contaminated
environment (Verma and Jaiswal 2016). Microbes that are involved in the degradation and detoxification of organic and inorganic pollutants are Mycobacterium,
Acinetobacter, Flavobacterium, Actinobacteria, Alcaligenes, Beijerinckia,
Arthrobacter, Methylosinus, Bacillus, Micrococcus, Serratia, Nitrosomonas, Rhizoctonia, Pseudomonas, Nocardia, Phanerochaete, Penicillium, Xanthobacter, and
Trametes. Bioremediation involves three main processes: biotransformation (conversion of organic and inorganic pollutants into less or nonhazardous molecules),
4
G. Saxena et al.
2006; Schue et al. 2009; Liu et al. 2011).
Moreover, the genetic engineering of plants also performed to enhance the
accumulation and tolerance capacity as well as detoxification potential for heavy
metal pollutants and to increase the biomass and growth of plants in metal contaminated sites (Hassani 2014). Metallothioneins (MTs) are the unique cysteine-rich
peptides that are relevant to higher metal-binding capacity in hyperaccumulating
plants and have been cloned to develop the genetically engineered plants for
phytoremediation of organic and inorganic pollutants. Tobacco plant was the first
genetically engineered plant for the phytoremediation of explosives and halogenated
organic pollutants (Doty et al. 2000). Many reports have been published on the
genetic engineering of plants and their role in the phytoremediation of contaminated
soil and water environment (Cherian and Oliveira 2005; Pilon-Smits 2005; Eapen
et al. 2007; Doty 2008; Macek et al. 2008; James and Strand 2009; Kawahigashi
2009; Van 2009). Recently, James and Strand (2009) reported the dehalogenation of
tetrachloroethylene (PCE) by hybrid poplar trees under controlled field conditions.
Genetically modified organisms can be also used as biosensors for related mixures of
agrochemicals, petroleum products, metals, and toxins that are found in the environment, but cannot be directly in soil or water (Ozcan et al. 2011).
3 Environmental Bioremediation Technologies
Environmental bioremediation technologies broadly can be classified into two major
categories: bioremediation and phytoremediation.
3.1 Bioremediation
Bioremediation is the eco-friendly technique wherein biological agents (microbes
and plants or their enzymes) are used to degrade and detoxify the organic and
inorganic pollutants to safeguard the environment and public health in low-cost
and efficient manner (Azubuike et al. 2016; Bharagava et al. 2018; Kishor et al.
2018). A range of bioremediation techniques have been developed by researchers to
date; but due to diverse characteristics of pollutants and merits and demerits, no
single bioremediation technique can provide full-scale solution to contaminated
environment (Verma and Jaiswal 2016). Microbes that are involved in the degradation and detoxification of organic and inorganic pollutants are Mycobacterium,
Acinetobacter, Flavobacterium, Actinobacteria, Alcaligenes, Beijerinckia,
Arthrobacter, Methylosinus, Bacillus, Micrococcus, Serratia, Nitrosomonas, Rhizoctonia, Pseudomonas, Nocardia, Phanerochaete, Penicillium, Xanthobacter, and
Trametes. Bioremediation involves three main processes: biotransformation (conversion of organic and inorganic pollutants into less or nonhazardous molecules),
4
G. Saxena et al.