Acidophilic microorganisms

Mann, H., W.S. Fyfe, R. Kerrich, and M. Wiseman. 1989. Retardation of toxic heavy metal dispersion from nickel-copper mine tailings, Sudbury district, Ontario role of acidophilic microorganisms. I. Biological pathway of metal retardation. Biorecovery 1 155-172. 

Johnson DB (1998) Biodiversity and ecology of acidophilic microorganisms. FEMS Microbiol Ecol 27 307-317... 

Mann H. and Fyfe W. S. (1989) Metal uptake and Fe-, Ti-oxide biomineralization by acidophilic microorganisms in mine-waste environments, Elliot Lake, Canada. Can. J. Earth Sci. 26, 2731-2735. 

Also present in certain environments are acidophilic microorganisms whose normal metabolic processes result in the oxidation and solubilization of minerals, usually metal sulfides. This process is responsible for acid runoff from disused mines, spoilage tips, and ore bodies. Such acid runoff may contain substantial amounts of metal ions such as Cu(II), which have been solubilized or leached out by the action of the acid. Indeed, it is probable that Roman and earlier Mediterranean civilizations obtained copper from this copper-rich acid runoff. 

A 5-(methylthio)-6-(C30H61)-benzo[b]thiophene-4,7-quinone has been isolated from cultures of an extremely thermophilic and acidophilic microorganism.502 In connection with the structure determination of this natural product, 5-bromo-6-methylbenzo[6]thiophene-4,7-quinone was treated with MeS, to give mainly the 5-SMe derivative. Unexpectedly, a minor product from this reaction was the 5-SMe, 6-CH2SMe compound, formed by both nuclear and side-chain methylthiolation.503... 

Another important factor affecting microbial activity is pH. Microorganisms that can grow under acidic (pH < 4) or alkaline (pH > 10) conditions are termed acidophiles or alkalophiles, respectively. Most bacteria, however, are neutrophiles. Neutrophiles can tolerate pH levels between 5 and 9, but their optimum growth is observed in a relatively narrow range around neutrality, i.e., between... 

The mesophiles A. thiooxidans and A. ferrooxidans have been found in equal proportions in mine effluents regardless of geological and climatological conditions. The temperature optimum for A. ferrooxidans and A. thiooxidans lies between 15 °C and 35 °C. Both are acidophiles and can tolerate a pH range of 1.5-6.0, with optimum growth between pH 2.0 and 2.5. The ability of these microorganisms to adapt and tolerate different pH and metal concentrations... 

EPSs protect microorganisms as a general physical barrier. Their production is a direct response to selective environmental pressures including osmotic stress, temperature, pH, pressure, and light intensity. In the cases of acidophilic or thermophilic species and Archaea, EPSs aid in adapting to extreme conditions. 

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