Biosorption of heavy metals by micromycetes: specificity of the process, mechanisms, kinetics
Skugoreva S.G., Kantor G.Ya., Domracheva L.I.
Section: Theoretical problems of ecology
One of the ways to remove heavy metal (HM) compounds from the environment is biosorption. Most studies on
biosorption are carried out on microorganisms, among which micromycetes occupy leading positions. They have a high
degree of adaptation and resistance to the action of HM, are able to accumulate and transform HM compounds, show high sorption activity in relation to them. A feature of the cell wall of micromycetes is the predominance of polysaccharides
(in particular, chitin), and the presence of melanins. Fungi biomolecules have different functional groups in
their composition, the donor atoms of which (binding sites) cause binding to the HM ions. The nature of the binding
can be explained from the standpoint of the Pearson acid-base principle (concept of HSAB – hard and soft acids and
bases). The article provides an overview of the literature data on the sorption capacity of micromycetes of various classes,
genera and species to various HM.
Fundamental to understanding the process of biosorption is knowledge about the mechanism of the process. Based
on cell metabolism, biosorption mechanisms can be classified into metabolism-independent and metabolism-dependent.
Based on the location of biosorption, the following are distinguished: 1) intracellular accumulation; 2) extracellular
accumulation and sedimentation; 3) sorption and precipitation on the cell surface. The mechanisms belonging to the
first two groups are dependent on metabolism and are due to the processes of complex formation, precipitation, and ion
exchange; and the last group of mechanisms is also adsorption (physical and chemical sorption). The article discusses
the basics of the mechanisms, their causes, features and examples of micromycetes, in which this mechanism prevails.
One of the most important characteristics of the HM sorption by biological objects is the dependence of the sorption
rate on the process parameters, which is described by the kinetic sorption equation. The article discusses the most
common models for the description of bisorption: the pseudo-first and pseudo-second order model, the Elovich equation,
and the parabolic diffusion model.
Keywords: micromycetes, heavy metal ions, biosorption, mechanisms of biosorption, kinetics of biosorption
Article published in number 2 for 2019 DOI: 10.25750/1995-4301-2019-2-014-031
ISSN 1995-4301
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