transformation (Ohkawa et al. 1999; Ma et al. 2001): (I) conversion (through
oxidations, reductions, and hydrolysis), (II) conjugation (chelating with glutathione,
sugars, and amino acids), or (III) compartmentation (by-products from the previous
phase are converted, bonded to the cell wall or lignin, and deposited in some
vacuoles of the plant system.
7.5 Phyto-Transformation Enzymology and Biochemistry
As other eukaryotes, the pathways for degradation of many organic pollutants are
similar in plant systems (Lamoureux and Rusness 1986; Vogeli-Lange and Wagner
1990; Meplan 2011). Based on the activation and imposed toxicity, mutagenicity
and carcinogenicity by chlorinated aliphatic compound degradation in human systems gain importance in research; the metabolism of such may vary even within the
same homologous series, but often it releases free radicals after oxidization. This
action was mainly observed with carbon tetrachloride metabolism when compared to
a lesser extent in other chlorinated methanes (Henschler 1990). In the dechlorination
pathway was observed the formation of epoxides when the glutathione is conjugated
with polychlorinated ethenes such as trichloroethylene (TCE) and perchloroethylene
(PCE) (Henschler 1990; Qiu et al. 1994), suggesting the suitability of microbes for
phytoremediation purposes by holding the eminent capacity of transforming metal
contaminates into a non-bioavailable state or reducing their toxicity to the plants and
environment.
8 Optimization of Metal Phytoextraction with Agronomic
Practices
The extent of metal contaminant removal is greatly affected by the selection of a
suitable plant variety for remediation. Ecosystem protection has to be considered
before selecting the plants for remediation, although metal extraction is the main
attraction; native plant species will be given importance excluding exotic plant
usages because the latter may affect the harmony of the ecosystem by their invasion.
The propagation of weedy crop species may be avoided by giving preference to the
general crops, but the downside is the palatable risks it may pose to grazing animals
after remediation.
8.1 Plant Selection
Plant selection is important for the phytoremediation process; to achieve good
remediation of metal contaminants, hyper-accumulators may be given preference.
4 Recent Advances in Phytoremediation of Toxic Metals from Contaminated. . .
101
oxidations, reductions, and hydrolysis), (II) conjugation (chelating with glutathione,
sugars, and amino acids), or (III) compartmentation (by-products from the previous
phase are converted, bonded to the cell wall or lignin, and deposited in some
vacuoles of the plant system.
7.5 Phyto-Transformation Enzymology and Biochemistry
As other eukaryotes, the pathways for degradation of many organic pollutants are
similar in plant systems (Lamoureux and Rusness 1986; Vogeli-Lange and Wagner
1990; Meplan 2011). Based on the activation and imposed toxicity, mutagenicity
and carcinogenicity by chlorinated aliphatic compound degradation in human systems gain importance in research; the metabolism of such may vary even within the
same homologous series, but often it releases free radicals after oxidization. This
action was mainly observed with carbon tetrachloride metabolism when compared to
a lesser extent in other chlorinated methanes (Henschler 1990). In the dechlorination
pathway was observed the formation of epoxides when the glutathione is conjugated
with polychlorinated ethenes such as trichloroethylene (TCE) and perchloroethylene
(PCE) (Henschler 1990; Qiu et al. 1994), suggesting the suitability of microbes for
phytoremediation purposes by holding the eminent capacity of transforming metal
contaminates into a non-bioavailable state or reducing their toxicity to the plants and
environment.
8 Optimization of Metal Phytoextraction with Agronomic
Practices
The extent of metal contaminant removal is greatly affected by the selection of a
suitable plant variety for remediation. Ecosystem protection has to be considered
before selecting the plants for remediation, although metal extraction is the main
attraction; native plant species will be given importance excluding exotic plant
usages because the latter may affect the harmony of the ecosystem by their invasion.
The propagation of weedy crop species may be avoided by giving preference to the
general crops, but the downside is the palatable risks it may pose to grazing animals
after remediation.
8.1 Plant Selection
Plant selection is important for the phytoremediation process; to achieve good
remediation of metal contaminants, hyper-accumulators may be given preference.
4 Recent Advances in Phytoremediation of Toxic Metals from Contaminated. . .
101