Chemical Interactions between Mercurial Species and Surface Biomolecules
173
reintroduction in aqueous phase, as expected, based on the well-documented
mercury cycle.
Ben-Bassat and Mayer (1975, 1977) also reached the same conclusion, using
however, a more detailed approach, considering the effect of cell concentration in
mercury volatilization rates.
10
The Surface of Some Fungal Cells
The eukaryotic cells of fungi can be divided into three main groups: moulds,
yeasts and mushrooms. The moulds are filamentous fungi, widespread in nature,
and commonly present in foods. The yeasts are unicellular fungi, important from
the industrial point of view, responsible for several fermentation processes. The
mushrooms are filamentous fungi that present fruiting bodies, important as
edible organisms.
From the ecological point of view, fungi are not so important as bacteria and
algae, especially in sites contaminated with heavy metals. However, a few reports
are available, mainly focusing on the use of fungi as biosorbent materials for the
decontamination of heavy metal solutions. For a detailed description of some
structural polysaccharides of some fungi and lichens, the reader should consult
the specific literature (Bergter and Gorin 1983). Again, from the ecological point
of view, fungal cells are not of fundamental significance; however, mention can
be made of the reduction of mercury to its elemental state by the yeast
Cryptococcus, whose metabolic activity of mercury involves incorporation of the
mercury compound by both cell wall and cellular membrane, as well as in
vacuoles inside the cytoplasm (Brunker and Bott 1974). Analogously, another
yeast, Saccharomyces cerevisiae, accumulates the metals copper, cobalt and
cadmium, being the incorporation of heavy metals associated to the protein
content of the cell wall, as well as to the inner glucan and chitin layer of the cells.
More recently, Mishra and Chaudhury (1996) studied zinc uptake by Penicillium
sp. cells, also concluding for the adsorptive nature of the process.
11
Microbial Resistance and Biochemical Effects of Mercury
As described in the literature, some microorganisms can conduct methylation
and demethylation reactions as well as several other biochemical reactions
involving mercurial compounds. This so-called detoxification process, i.e, the
production of volatile elemental mercury, seems to be dependent on the
enzymatic apparatus of the microbial cells, and this is the basis for the resistance
of cells, and consequently their ability to survive in the presence of mercurial
compounds. Trevors et a1. (1985) published an extensive list of mercury-resistant
173
reintroduction in aqueous phase, as expected, based on the well-documented
mercury cycle.
Ben-Bassat and Mayer (1975, 1977) also reached the same conclusion, using
however, a more detailed approach, considering the effect of cell concentration in
mercury volatilization rates.
10
The Surface of Some Fungal Cells
The eukaryotic cells of fungi can be divided into three main groups: moulds,
yeasts and mushrooms. The moulds are filamentous fungi, widespread in nature,
and commonly present in foods. The yeasts are unicellular fungi, important from
the industrial point of view, responsible for several fermentation processes. The
mushrooms are filamentous fungi that present fruiting bodies, important as
edible organisms.
From the ecological point of view, fungi are not so important as bacteria and
algae, especially in sites contaminated with heavy metals. However, a few reports
are available, mainly focusing on the use of fungi as biosorbent materials for the
decontamination of heavy metal solutions. For a detailed description of some
structural polysaccharides of some fungi and lichens, the reader should consult
the specific literature (Bergter and Gorin 1983). Again, from the ecological point
of view, fungal cells are not of fundamental significance; however, mention can
be made of the reduction of mercury to its elemental state by the yeast
Cryptococcus, whose metabolic activity of mercury involves incorporation of the
mercury compound by both cell wall and cellular membrane, as well as in
vacuoles inside the cytoplasm (Brunker and Bott 1974). Analogously, another
yeast, Saccharomyces cerevisiae, accumulates the metals copper, cobalt and
cadmium, being the incorporation of heavy metals associated to the protein
content of the cell wall, as well as to the inner glucan and chitin layer of the cells.
More recently, Mishra and Chaudhury (1996) studied zinc uptake by Penicillium
sp. cells, also concluding for the adsorptive nature of the process.
11
Microbial Resistance and Biochemical Effects of Mercury
As described in the literature, some microorganisms can conduct methylation
and demethylation reactions as well as several other biochemical reactions
involving mercurial compounds. This so-called detoxification process, i.e, the
production of volatile elemental mercury, seems to be dependent on the
enzymatic apparatus of the microbial cells, and this is the basis for the resistance
of cells, and consequently their ability to survive in the presence of mercurial
compounds. Trevors et a1. (1985) published an extensive list of mercury-resistant