Metallophilic fungi research: an alternative for its use in the bioremediation of hexavalent chromium

Abstract

Contamination by hexavalent chromium has had a large impact on modern society and human health. This problem is a consequence of its great industrial applicability to several products and processes. Short-term exposure to hexavalent chromium can cause irritation, ulceration in skin and stomach and in addition to cancer, dermatitis, and damage to liver, renal circulation and nervous tissues, with even death being observed in response to long-term exposures. Many techniques have been used for the remediation of this pollutant, including physical and chemical approaches and, in more recent years, biological methods. Filamentous fungi isolated from contaminated sites exhibit a significant tolerance to heavy metal; hence, they are an important source of microbiota capable of eliminating hexavalent chromium from the environment. However, these microorganisms can do so in different ways, including biosorption, bioreduction, and bioaccumulation, among others. In this review, we explore several of the most documented mechanisms that have been described for fungi/hexavalent chromium interactions and their potential use in bioremediation.

Tolerance and mycoremediation of silver ions by Fusarium solani

“…Septa became very thin (Figure 3d). Exopolysaccharides and other metabolites immobilize heavy metals to prevent their entry to the cells (avoidance mechanism) (García-Hern andez et al, 2017;El-Sayed et al, 2017). Electron dense particles were distributed outside the cell, on the cell wall and plasma membrane and some were located within the cytoplasm, revealing the main interaction occurred in the cell wall (Figure 3e).…”

Bioremediation and tolerance of zinc ions using Fusarium solani

“…The precipitation outside the cell seemed to be the first defense of F. solani against Zn(II). The biosorption of heavy metals depended on ionic species associating with the cell surface or extracellular polysaccharides, proteins, and chitins ( Garcıa-Hernandez et al., 2017 ). The complete lysis of cytoplasmic organelles and the formation of some precipitates within the dark cell wall was observed ( Figure 3 c) and this distortion may be due to the oxidative stress of Zn(II).…”

“…Maximum capacity at 600 mg/l Zn(II) associated with the higher mass transfer and kinetic energy, and availability of metal ions thus the possibility of collision between the biosorbent and the ions ( El-Gendy et al., 2017 ). Reducing the biosorption capacity at higher concentrations could be ascribed to the inadequacy of free accessible binding sites and the competition between ions ( Garcıa-Herna´ndezet al. 2017 ).…”

Removal of Pb (II), As (III), and Cr (VI) by nitrogen‐starved Papiliotrema laurentii strain RY1

“…Fungi have been reported to be useful in bioabsorption, bioaccumulation along with extracellular and intracellular detoxification of chromium . As from the experiments, the events occurring in P. laurentii were: (a) Chromium interacts with yeast cell surface polysaccharides.…”