metal ion (zinc, cobalt, and cadmium) was quick until it reaches equilibrium
condition (Yousefi et al. 2015). For example, Godlewska-Żyłkiewicz et al.’s
(2019) experiment showed that the effectiveness of biosorption of Pd (II) and Pt
(II) on Aspergillus sp. within 15 min reached 97% and 91%, respectively.
3.5 The Influence of Biomass Dosage
Fungal biomasses are applicable to eliminate heavy metals from the contaminated
terrestrial and aquatic ecosystem. According to Godlewska-Żyłkiewicz et al.’s
(2019) study, the efficiency of biosorption of ions increases as the mass of biomass
increases to a value of 0.013 g (0.1 g of wet mass). This is probably the influence of a
higher number of binding sites on the surface of the biosorbent. The efficiency of
biosorption was constant in the range of 0.013–0.066 g of biomass dosage demonstrating the formation of balance among the ions bound to the biosorbent and those
residual in the solution. According to Saad et al.’s (2019) study, the amount of
copper (II) uptake by Aspergillus tamarii NRC 3 biomass was improved as the
preliminary amount of biomass increased, and the uptake of Cu
+2 was recoded
(92.40%) in a liquid containing 5 g of wet weight biomass (Table 17.1).
4 Biosorption Mechanisms of Heavy Metals Using Fungi
Microorganisms that are continually exposed to heavy metal stress develop adapting
mechanisms to the metal contaminants. Mechanisms involved in biosorption are
often classified based on varied criteria: (1) based on cell metabolism, they’re
classified as metabolism-dependent and non-metabolism-dependent, while
(2) based on the location where the metal elimination from liquids happens,
biosorption can be classified as extracellular accumulation/precipitation, cell surface
sorption/precipitation, and intracellular accumulation (Bellion et al. 2006; Vankar
and Bajpai 2008; Dhankhar and Hooda 2011; Thakur et al. 2015; Shakya et al. 2015;
Siddiquee et al. 2015; Bahobil et al. 2017). Different mechanisms involved in
biosorption phenomena are summarized in Fig. 17.1.
Generally, two mechanisms are proposed for overwhelming heavy metal resistance in fungi. The first mechanism is an extracellular (chelation and cell membrane
binding) sequestration, and the second is intracellular physical sequestration of metal
by binding to proteins or other ligands to prevent it from harming the metal-sensitive
cellular targets. Along these lines, extracellular mechanisms are mainly implied
within the avoidance of metal entry, whereas intracellular sequestration systems
intend to downsize the metal stress within the cytosol (Baldrian 2003; Anahid et al.
2011). In the extracellular mechanism, different organic molecules that do not
belong to the matrix of the cell membrane are excreted by the fungal cell to chelate
metal ions. Binding to the cell membrane of fungus is named biosorption (Fawzy
17 Mycoremediation: Fungal-Based Technology for Biosorption of Heavy Metals. . .
361
condition (Yousefi et al. 2015). For example, Godlewska-Żyłkiewicz et al.’s
(2019) experiment showed that the effectiveness of biosorption of Pd (II) and Pt
(II) on Aspergillus sp. within 15 min reached 97% and 91%, respectively.
3.5 The Influence of Biomass Dosage
Fungal biomasses are applicable to eliminate heavy metals from the contaminated
terrestrial and aquatic ecosystem. According to Godlewska-Żyłkiewicz et al.’s
(2019) study, the efficiency of biosorption of ions increases as the mass of biomass
increases to a value of 0.013 g (0.1 g of wet mass). This is probably the influence of a
higher number of binding sites on the surface of the biosorbent. The efficiency of
biosorption was constant in the range of 0.013–0.066 g of biomass dosage demonstrating the formation of balance among the ions bound to the biosorbent and those
residual in the solution. According to Saad et al.’s (2019) study, the amount of
copper (II) uptake by Aspergillus tamarii NRC 3 biomass was improved as the
preliminary amount of biomass increased, and the uptake of Cu
+2 was recoded
(92.40%) in a liquid containing 5 g of wet weight biomass (Table 17.1).
4 Biosorption Mechanisms of Heavy Metals Using Fungi
Microorganisms that are continually exposed to heavy metal stress develop adapting
mechanisms to the metal contaminants. Mechanisms involved in biosorption are
often classified based on varied criteria: (1) based on cell metabolism, they’re
classified as metabolism-dependent and non-metabolism-dependent, while
(2) based on the location where the metal elimination from liquids happens,
biosorption can be classified as extracellular accumulation/precipitation, cell surface
sorption/precipitation, and intracellular accumulation (Bellion et al. 2006; Vankar
and Bajpai 2008; Dhankhar and Hooda 2011; Thakur et al. 2015; Shakya et al. 2015;
Siddiquee et al. 2015; Bahobil et al. 2017). Different mechanisms involved in
biosorption phenomena are summarized in Fig. 17.1.
Generally, two mechanisms are proposed for overwhelming heavy metal resistance in fungi. The first mechanism is an extracellular (chelation and cell membrane
binding) sequestration, and the second is intracellular physical sequestration of metal
by binding to proteins or other ligands to prevent it from harming the metal-sensitive
cellular targets. Along these lines, extracellular mechanisms are mainly implied
within the avoidance of metal entry, whereas intracellular sequestration systems
intend to downsize the metal stress within the cytosol (Baldrian 2003; Anahid et al.
2011). In the extracellular mechanism, different organic molecules that do not
belong to the matrix of the cell membrane are excreted by the fungal cell to chelate
metal ions. Binding to the cell membrane of fungus is named biosorption (Fawzy
17 Mycoremediation: Fungal-Based Technology for Biosorption of Heavy Metals. . .
361