Mycoremediation of heavy metals: processes, mechanism and affecting factors
Vinay Kumar and Shiv Kumar Dwivedi
Summarized by Anna Geldert
What data were used? In this review, researchers assessed data from over 300 previous studies on mycoremediation, a process which uses fungi to remove pollutants such as heavy metals from the environment. These studies included findings on the mycoremediation potential of 62 living species of fungi, and 21 dead species. In total, the review considered 11 types of heavy metal pollutants (mercury, cadmium, lead, chromium, copper, arsenic, manganese, nickel, cobalt, zinc and iron) as well as data on drinking water standards, and health impacts of each heavy metal from the World Health Organization (WHO).
Methods: The goal of this review was to synthesize data from existing research, and to identify which factors most affect fungi mycoremediation potential. The authors looked for trends and patterns from previous studies, and summarized findings related to the health impacts of heavy metal exposure to fungal species, as well as the biological, chemical, and physical processes that are used for the absorption of pollutants. They also identified the most important factors affecting the rate of absorption for both living fungi and dead fungal biomass.
Results: In general, results demonstrate that both heavy metal tolerance and absorption potential differs greatly among species of fungi. Species belonging to the class ascomycete were found to tolerate higher concentrations of heavy metal pollutants, though the explanation for this is still unclear. Both living and dead fungal biomasses were able to absorb heavy metals through a variety of biological processes in the cell wall, and this absorption may be increased further through physical and chemical treatments. In regard to factors that impact absorption rate, the review found that lower pH levels, high agitation (water disturbance) rates, and low flow rates all consistently increased the absorption rate of tested fungi. Factors such as temperature, time, and heavy metal concentration varied based on the species of fungi. Lastly, this study concludes that dead fungal biomass will most likely work better than living fungi for mycoremediation, since varying pH levels, temperatures, and heavy metal concentrations are not limiting factors as dead fungal masses do not need to be kept alive.
Why is this study important? This study is useful because it draws conclusions from a large body of existing work on mycoremediation, and recognizes important trends in related findings. This allows for comparisons on the mycoremediation potential of various fungal species, treatment methods, and treatment conditions, which would be much more difficult without a cohesive summary paper such as this one. This study will enable future researchers, and engineers to create novel and efficient methods for treatment of heavy metal wastewater with fungus.
The big picture: Pollution is one of several environmental challenges facing our planet today, with heavy metal pollutants being one of the most hazardous, due to its negative impacts on human health. Current methods for treating heavy metal contaminants in wastewater are often not economically or environmentally sustainable. Mycoremediation may provide a sustainable solution to this problem, due to fungi’s inherent ability to absorb environmental pollutants, such as heavy metals. This review provides guidance on what fungal species, treatment methods, and treatment conditions would make this remediation process most effective and efficient.
Citation: Kumar, V., & Dwivedi, S. K. (2021). Mycoremediation of heavy metals: processes, mechanisms, and affecting factors. Environmental Science and Pollution Research, 28(9), 10375–10412. https://doi.org/10.1007/s11356-020-11491-8