methyl mercury and Microorganisms


There are gaps in the science literature regarding how the human body derives methyl mercury from inorganic dental mercury.

After much searching, I've come up with no references that would indicate human metabolic processes perform this mercury transformation. One does find that methyl cobalamin (methyl B12) will spontaneously react with inorganic mercury creating a methyl mercury compound. This reaction occurs just by having the two molecules in solution in a petri dish.

Plenty of evidence exists to show human demethylization and the creation of mercury proteins. There is data to show mercury binding into all kinds of human molecular structures causing disruption.

Metabolic conversion to free form methyl mercury by humans or mammals cannot be substantiated in the literature. One reference I found, and included on another page, addresses this explicitly.

So how does the mercury get to be methyl mercury in the human starting from dental amalgam ? Dental amalgam irrefutably contains only inorganic mercury. Another agent must be at work. Microorganisms in the mouth and GI track gut quickly come under suspicion.

Behold, the gut does contain micro flora with this capability. Yeast, strep, staff and E. coli all perform the transformation, it's referenced here, it's proven.

Strep and staff are 100% pathogenic. Your health has near zero tolerance for these organisms, though they often maintain a limited presence outside the cell linings of the gut. It is very unlikely these pathogens contribute to a long term mercury conversion process. Infections of these organisms are generally acute in nature.

Yeast and E. coli are the two most compelling organisms to suspect since both are usually not pathogenic, often behave symbiotically, and are known to live in most guts.The ability to transform dental mercury to methyl mercury is already living within the mouth and GI track of everyone who has a mercury dental filling.

Read on for medical and scientific journal references that substantiate this point.

"Transformations of inorganic mercury by Candida albicans and Saccharomyces cerevisiae"; Applied and Environmental Microbiology, Jan 1991; 57:1:245-247; S Yannai; I Berdicevsky, L Duek; Dept. of Food Engineering and biotechnology, and Unit of Microbiology, Faculty of Medicine, Technion-Israel Institute of Technology

"Saccharomyces cerevisiae and Candida albicans were incubated with 0.25, 0.5, or 0.75 ug of Hg (as HgCl2) per ml of Nelson's medium in the presence of trace amounts of oxygen at 28 °C for 12 days. Two controlled media were used, one without add Hg and one with out yeast inoculum. Yeast cell growth was estimated after 1, 2, 3, and 8 days of incubation. The contents of organomercury in the system and of elemental mercury released from the media and collected in traps were determined at the end of the experiments. The results were as follows. (i) C. albicans was the more mercury-resistant species, but both yeast species failed to grow in the media containing 0.75 ug per ml. (ii) (iii) The amounts of organomercury produced by the two species were proportional to the amount of HgCl2 added to the medium. In all cases C. albicans produced considerably larger amounts of elemental Hg produced were all similar in the case of C. albicans. (iv) Neither organomercury nor elemental Hg was produced in any of the control media."

Experiment and Findings
1. Anerobic fermentation process, closed system with outlet only.
2. 14 day fermentation period.
2. Culture flask and fermentation effluent traps.
3. In the Candida albicans flasks, 0.9%-1% of the original mercury/ml was free as organomercury.
4. In the traps 9-10% of the original mercury/ml was free as organomercury.
5. There was not a full accounting of original mercury: how much in yeast ? how much still in original species ?
6. Authors believe the organomercury was methyl mercury, they are certain it was a carbon bearing compound.

"Speciation of methyl mercury and Hg(II) using bakers yeast biomass (Saccharomyces cerevisiae) determination by continuous flow mercury cold vapor generation atomic absorption spectrometry"
; Anal. Chem.; 1995; 67:750-754; Y Madrid, Ca Cabrera, T Perez-Corona, C Camara; Departmento de Quimica analitica, Facultad de Quimicas, Universidad Complutense, 28040 Madrid, Spain.

"Bakers yeast cells (Saccharomyces cerevisiae) were successfully used to selectively separate methyl mercury and Hg(II). Several parameters affecting the degree of biosorption and the binding kinetics of methyl mercury and Hg(II) were evaluated: solution pH; temperature,incubation time, amount of biomass and analyte, and presence of foreign ions. methyl mercury is immediately bound to the yeast cells over a wide pH and temperature range. The fraction of methyl mercury bound was in all cases 100% and was unaffected by the parameters mentioned above. Hg(II) has less affinity for yeast cells and remains in solution, although the percentage of Hg(II) bound to the cell mass does increase at high incubation time (3 hours) and biomass. Of the foreign ions tested, chloride at high concentrations strongly increases the Hg(II) binding efficiency. methyl mercury and Hg(II) are quantitatively separated under optimum conditions, i.e. 30 minutes incubation time at pH 7.0 and 37 °C. The results were compared with those obtained using a S. cerevisiae isolate, and no significant differences were observed. Our work suggests that the cell rapidly reduces CH3Hg+ to more volatile species such as Hg(I) or Hg0, whereas Hg2+ is slowly bound and reduced, perhaps because of the different toxicities of the two species. The method was applied to the selective determination of Ch3Hg+ and Hg(II) spiked water samples. In all cases good recoveries were obtained."

"The cell membrane is one of the major barriers along the toxicological pathways of hazardous substances. Consequently, living cell systems can be used as an analytical tool for trace analysis.

Various microorganisms are capable of binding dissolved metals in a variety of environments. Microbes, composed mainly of polysaccharides, proteins, and lipids, offer particularly abundant metal-binding functional groups. Other biological processes that can occur include methylization, demthylization, and reduction. These properties can be used not only for removing heavy metal ions from polluted environments but also for differentiating species according to their toxicity. although living organisms have been widely used to preconcentrate metal ions, there have been few attempts to apply this kind of substrate to metal speciation. Neidhart et al. used human red blood cells for specific sampling of chromate even at high levels of Cr(III).

Mercury is a toxic metal whose toxicity depends on its chemical form. methyl mercury is more toxic tha Hg2+, not only for humans but also for microorganisms. Microorganisms (bacterias, yeasts, and other fungi) mediate three transformations of mercury: they reduce Hg(II) to Hg0, they break down methyl mercury (and other organomercury compounds), and they methylate Hg(II). Hg(II) is also reduced and methylated by chemical reactions in the environment other than those mediated by microorganism. This paper discusses the potential of the yeast cell for the speciation of methyl mercury and Hg(II). The effects of Ph, temperature, incubation time, mercury and yeast concentration, and interferences from other metals are examined."

"Sub-cellular Location of Mercury in Yeast Grown in the Presence of Mercuric Chloride"; Journal of General Microbiology; 1975; 86:66-74; AD Murray; DK Kidby; Dept. of Microbiology, College of Biological Science, University of Guelph, Guelph, Ontario, Canada.

"The distribution of 203Hg in Saccharomyces cerevisiae grown in the presence of mercuric chloride has been examined by physical and chemical fractionation procedures and autoradiography. The major fraction of the bound mercury is tightly bound to the wall. A significant quantity of mercury penetrates to the cytoplasm but only a minor fraction is present as low molecular weight compounds. The wall associated mercury is not readily released by extraction with sodium hydroxide or ethylenediamine but a major fraction is solubilized by Pronase and Helicase treatment. Isolated walls are capable of binding their own weight of mercury to high affinity adsorption sites. The major role of the cell envelope in the in vivo binding of mercury and the penetration to the cytoplasm of mercury was confirmed by autoradiography."

"Growth of yeasts is inhibited by most heavy metals which have been examined (White & Munns, 1951). Of the group comprising cadmium, lead and mercury, the last has been extensively characterized as an inhibitor of enzymes due to it's number of functional groups (Vallee & Ulmer, 1972). The extracellular B-glucosidase and B-fructosidase of yeast have been shown to be extremely sensitive to mercury (Mealor & Townshend, 1968; Kaplan & Tacreiter, 1966). However, despite the well documented phenomenom of mercury inhibition of yeast, at both the moleular and cell level, there has been no investigation of the distribution of mercury within the cell. We attempted to define the distribution of mercury within the cell. We attempted to define the distribution of mercury in growing yeasts and to indicate the general nature of the mercury binding sites."

Experiment and Findings
1. aerobic vs anaerobic conditions not specified, growth medium was liquid.
2. Incubation time was 15 hours.
3. Nearly all the mercury present was in the yeast cells, with almost none left in growth medium.
4. Major fraction of mercury was bound into the cell walls, only a small proportion of this appeared to be in weakly bound ion exchange positions.
5. Yeast walls are capable of binding approximately their own weight of mercury.

"The methylization of mercuric chloride by human intestinal bacteria"; Experentia, 31:9; 1975; Sept 15, 1064-5; IR Rowland; P Grasso; MJ Davies; British Industrial Biological Research Association, Woodmansterne Road, Cashalton, Surrey, SM5 4DS, England.

"Most strains of staphylococci, steptococci, yeasts and E. coli isolated from human feces, could synthesize methyl mercury compounds. In contrast, few strains of obligate anerobes could do so. Up to 6 ng methyl mercury/ml were formed in 44 hours from 2 ug / ml mercuric chloride."

Experiment and Findings
1. Except for lactobacillus and bifido-bacteria, all cultures incubated in aerobic conditions.
2. Streptococci had highest methylization rate, followed by Staph, and E. coli, then yeast.
3. Very few strains of GI friendly bacteria methylized. Those that did, produced extremely little.

"Tissue content of mercury in rats given methylmeruric chloride orally: influence of intestinal flora."; Arch Environ Health; 35:3, 1980 May-June; 155-60; IR Rowland; MJ Davies; JG Evans; British Industrial Biological Research Association, Woodmansterne Road, Cashalton, Surrey, SM5 4DS, England.

"The effect of intestinal flora on the absorption and disposition of mercury in tissues was investigated using conventional rats and rats treated with antibiotics to eliminate their gut flora.

Antibiotic treated rats given 203Hg labeled methylmercuric chloride orally had significantly more mercury in their tissues, especially in kidney, brain, lung, blood, and skeletal muscle, and also excreted less mercury in the feces than conventional rats. Furthermore, in the kidneys of the antibiotic treated rats, the proportion of mercury present as organic mercury was greater than in the kidneys of the conventional rats. The results support the hypothesis that the metabolism of methylmercuric chloride by the gut flora reduces the tissue content of mercury. When rats were administered 10 mg methylmercuric chloride/kg per day for 6 days, four of five of those given antibiotics developed neurological symptoms of toxicity, whereas only only one of five conventional rats given methylmercuric chloride was affected."

Facts and Findings
1. Inorganic Hg compounds are absorbed very slowly in the mammalian intestine tract.
2. Alkyl-mercurial (carbon bearing mercury ) compounds are rapidly and completely absorbed from the GI.
3. Rat feces were found to be free of bacteria after 3 days of the antibiotic regime.
4. After 30 days four of five rates given antibiotic treatment developed signs of severe methyl mercury chloride (CH3HgCl) poisoning.
5. Only 1 of five conventional rates developed severe CH3HgCl poisoning in the same period.
6. Intestinal microflora reduce the severity of damage to the granular layer of the cerebellum
7. Intestinal flora play a protective role by effectively reducing the toxicity of ingested CH3HgCl.

"Microbial transformations of metals"; Annu Rev Microbiol, 32:1978, 637-72; AO Summers; Dept. of Microbiology, University of Georgia, Athens, GA 30602

"Biological Methylation of Mercury...

Three alternative pathways for mercury metabolism have been proposed. (a) bacteria living in bottom sediment and sludge can carry out mercury methylation by excreting methylcobalamin, which serves as a methyl donor in vitro. Indeed, bottom dwelling bacteria, soil anerobes, and yeasts, have been shown to have the ability to methylate mercury....

(b) Second the mercury may be methylated by the normal bacterial flora of the gills and guts of the fish...

(c) The third alternative for methyl mercury production is totally abiotic, without the intervention of microbes or microbial metabolites..."

"Formation of methyl mercury by bacteria"; Appl Microbiol; 30:3, 1975; Sept; 424-32; MK Hamdy; OR Noyes; Dept. of Food Science, University of Georgia, Athens, GA 30602.

"Twenty three Hg2+ resistant cultures were isolated from sediment of the Savannah River in Georgia; of these, 14 were gram-negative shirt rods belonging to the Genera Escherichia and Enterobacter, six were gram positive cocci (three Staphylococcus sp. and three Streptococcus sp.) and three were bacillus sp. All the Escherichia, Enterobacter, and the bacillus strain were more resistant to Hg2+ that the strains of staphylococci and streptococci. Adaptation using serial dilutions and concentration gradient agar plate techniques showed that it was possible to select a Hg2+ resistant strain from a parent culture identified as enterobacter aerogenes. this culture resisted 1,200 ug of Hg2+ per ml of medium and produced methylmercury from HgCl2, but was unable to convert Hg2+ to volatile elemental mercury (Hg0). Under constant aeration (i.e., submerged culture), slightly more methylmercury was formed than in the absence of aeration. Production of methylmercury was cyclic in nature and slightly decreased if DL-homocysteine was present in the media, but increased with methylcobalamine. Is is concluded that the bacterial production of methyl mercury may be a means of resistance and detoxification against mercurial in which inorganic Hg2+ is converted to organic form and secreted into the environment."

"Effect of DL-homocysteine. Homocysteine was added in equimolar amounts to that of Hg2+ (0.25 umol of Hg2+ per ml of media) present in GBSB and the medium was then incubated aerobically. The results showed the absence of MM, as detected by TLC or GLC, in the benzene extract of control medium. It was also noted that the formation in the culture media after 3 and 20 days of incubation"

"Biotoxicity of Mercury as Influenced by Mercury(II) Speciation";
Applied and Environmental Microbiology, Oct. 1990, p. 3006-3016; RE Farrell; JJ Germida; PM Huang; Department of Soil Science, University of Saskatchewan.   

"Additions of cysteine at cysteine:Hg molar ratios greater than 1:10 to the M-IIY medium produced significant (P=0.01) increases in the IC50 to the extent that Hg toxicity was virtually eliminated at a cysteine:Hg molar ratio of 2:1."

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