Lead Induced Toxicity, Detoxification and Bioremediation 197

Table 11.1. Role of various plant species for the remediation of Pb.

Sr. No.

Plant species

Effect on Pb accumulation

References

1.

Spinacia oleracea

Application of S. oleracea with tartaric acid markedly

increased the uptake of Pb and its translocation from the root

to stem through the process of phytoextraction.

Khan et al.

2016

2.

Schoenoplectus californicus

S. californicus growing in marshy environments showed

increased Pb absorption by largely retaining it in their roots.

Arreghini et al.

2017

3.

Sesuvium portulacastrum

Enhancement in Pb levels in the shoot of S. portulacastrum

compared to Brassica juncea and Pb accumulation in its

upper portions was observed to be 3.4 mg g⁻¹ of dry weight.

Zaier et al.

2014

4.

Lolium multiflorum

Significant phytoremediation potential was shown by

L. multiflorum through the process of phytoextraction. The

contents of heavy metals transported from roots to the upper

parts were greater than that remained in the soil.

Salama et al.

2016

5.

Achillea wilhelmsii, Erodium

cicutarium, Nonnea persica

and Mentha longifolia

These plant species were most appropriate for

phytostabilizing Pb and had good potential for

phytoremediation.

Mahdavian et

al. 2017

6.

Coronopus didymus

The roots of C. didymus showed maximum Pb accumulation

compared to the shoot and C. didymus was recognized as a

good phytoremediation candidate in Pb-polluted soils.

Sidhu et al.

2018

7.

Chrysanthemum indicum

Greater remediation efficiency was shown by C. indicum

through increased clean-up of the Pb contaminated soils with

maximum concentration in the root followed by the shoot

and flower.

Mani et al.

2015

8.

Phragmites australis

95% of the Pb was removed from the Pb contaminated

water by using P. australis through the process of

phytostabilization.

Bello et al.

2018

9.

Daucus carota

Pb accumulation was observed to be increased in the

D. carota via chelate application and can be used as

a hyperaccumulator plant for Pb-phytoextraction and

phytostabilization from polluted soils.

Babaeian et al.

2016

Different strategies adopted by microorganisms to survive in heavy metal contaminated soils are

extrusion of metal ions by using metal efflux pumps, biotransformation of ions, intra/extracellular

metal sequestration, enzymatic usage, exopolysaccharide (EPS) generation, and metallothionein

and bio surfactants synthesis, etc. (Dixit et al. 2015, Igiri et al. 2018). Microorganisms can

further detoxify the metal ions by several different methods, including ion exchange, electrostatic

interaction, precipitation, surface complexation, etc. (Yang et al. 2015). Microorganisms have

negatively charged groups on their cell surface that facilitate them to bind to cationic metal ions

(Gavrilescu 2004).

Fungal hyphae remediate the heavy metal contaminated soils by intracellular sequestration

of toxic metal ions. Chitin, lipids, mineral ions, N-polysaccharide, polyphosphates and proteins

are major constituents of the cell wall of fungi. Fungal hyphae and their spores can eradicate the

heavy metal ions from the soil by ATPase pump-mediated uptake, extracellular and intracellular

precipitation and change in the oxidation state of metal ions. On the fungi cell wall outer surface,

there is the presence of various metal ions binding ligands/functional groups that enhanced the rate

of binding of toxic metals to hyphae, thereby reducing the availability of these toxic metals to plants.

The foremost metal-binding ligands present on the surface of the cell wall are the hydroxyl group,

carboxyl group, phosphoryl group, sulfate group, sulfite group, ester, amine group, carboxylate

group and sulfanyl group. Out of these functional groups, the amine group is most involved in metal

absorption as it can bind with both cationic as well as anionic metal ions by surface complexation

and electrostatic interaction, respectively (Gupta et al. 2015, Xie et al. 2016).