Biosorption is the process which involves higher affinity of a biosorbent towards sorbate (metal ions),
continued until equilibrium is established between the two components [19]. Saccharomyces cerevisiae
acts as a biosorbent for the removal of Zn (II) and Cd (II) through the ion exchange mechanism [61,62].
Cunninghamella elegans emerged as a promising sorbent against heavy metals released by textile
wastewater [63]. Heavy metal degradation involves energy for the cell metabolic cycle. The combined
active and passive modes of toxic metal bioremediation can be called bioaccumulation [64]. Fungi have
emerged as potential biocatalysts to access heavy metals and transform them into less toxic compounds [65].
Some fungi such as Klebsiella oxytoca, Allescheriella sp., Stachybotrys sp., Phlebia sp. Pleurotus
pulmonarius, Botryosphaeria rhodina have metal binding potential [66]. Pb (II) contaminated soils can
be biodegraded by fungal species like Aspergillus parasitica and Cephalosporium aphidicola with
biosorption process [67,68]. Hg resistant fungi (Hymenoscyphus ericae, Neocosmospora vasinfecta and
Verticillum terrestre) were able to biotransform a Hg (II) state to a nontoxic state [69]. Many of the
contaminants are hydrophobic, and these substances appear to be taken up by microbes through the
secretion of some biosurfactant and direct cell-contaminant association. Biosurfactants form stronger
ionic bonds with metals and form complexes before being desorbed from soil matrix to water phase due
to low interfacial tension [70].