Lead Induced Toxicity, Detoxification and Bioremediation 199

microbial inoculum under specific conditions of pH, temperature and dosage could aid plants to

remove heavy metals like Pb from contaminated soil efficiently.

Remediation of toxic contaminants from various substrates by employing a microbial agent,

fungus, is also known as mycoremediation. Fungi have a capacity to recover HMs owing to

filamentous structures that exhibit a charged group on the cell wall. In addition to functional groups,

they also display features of metal transporters by enzymatic activity, vacuolar sequestration and

antioxidant systems (Kumar 2017, Vacar et al. 2021). Fawzy et al. (2017) screened many fungal

species like Emercilla quadrillineata, Rhizopus stolonifier, Aspergillus niger, etc., and observed

an effective resistance even at higher concentrations of Pb in contaminated soil. Similarly, other

fungal isolates such as Rhizophagus irregularis and Funneliformis mosseae showed promising high

biomass of Helianthus annuus against Pb ions application (Hassan et al. 2013). Fungi, particularly

Aspergillus niger, revealed a detoxification mechanism in the environment by the processes of

compartmentalized sequestration, biosorption and chelation with organic acids. Thus, such pathways

can be used for decreasing lead levels through immobilization or mobilization (Bellion et al. 2006,

Iram et al. 2015).

Some species of fungi like Metarhizium and Paecilomyces can convert metallic lead into

chloropyromorphite in a lead mining site. This transformation occurred because of the organic acid

secreted by the fungi, which caused the precipitation of Pb (Rhee et al. 2012, Rigoletto et al. 2020).

Alongwith this, Povedano-Priego et al. (2017) confirmed that biomineralization of lead phosphate

in decaying wood caused tolerance to isolated fungi. They noted that Penicillium and Asperigillus

strains showed more tolerance to heavy metals. A summary of various algae and fungi involved in

the remediation of Pb from contaminated sites is presented in Table 11.2.

Table 11.2. Groups of microbes involved in phycoremediation/mycoremediation of Pb contaminated sites.

Microbes Group

Bioremediators

Sorption efficiency (mg g^–1)

References

Fungi

Aspergillus niger

34.4

Dursun et al. 2003

Saccharomyces cerevisiae

80

Farhan and Khadom 2015

Phanerochaete

chrysosporium

88.16

Iqbal and Edyvean 2004

Botrytis cinerea

107.1

Akar et al. 2005

Aspergillus terreus

59.67

Joshi et al. 2011

Algae

Codium vermilara

63.3

Romera et al. 2007

Cladophora sp.

13.7

Lee and Chang 2011

Spirogyra sp.

38.2

Lee and Chang 2011

Spirogyra sp.

140

Gupta and Rastogi 2008

Asparagopsis armata

63.7

Romera et al. 2007

Cystoseira barbata

196.7

Yalçın et al. 2012

11.5 Conclusion

Heavy metal Pb has a large number of applications in industries such as lead used as lead acetate in

sweeteners, installations of drinkable water, paints, additives used in gasoline and many more that

further increase the probability of Pb release, its exposure and penetration in all existing organisms

of our ecosystem. Beyond permissive limits, Pb accumulation inside the organisms creates toxic

hazards and severe morphological and physiological implications and finally decreases the

efficiency of the organism. Thus, the removal of Pb-based hazardous products should be firmly

perused in order to improve and avoid environmental as well as health risks. An essential criteria

for attaining Pb based contaminant-free environment require the development of highly efficient

bioremediation technologies such as phytoremediation, mycoremediation, phycoremediation and