Psychrotolerant acidophiles

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Growth of psychrotolerant Acidithiobacillus ferrooxidans SS3 on tetrathionate at 30ºC (circles) and 5ºC (squares) .
Growth of psychrotolerant Acidithiobacillus ferrooxidans SS3 on tetrathionate at 30ºC (circles) and 5ºC (squares) [1].

There have been a number of reports of uncontrolled bioleaching in cold environments such as Northern Canada and Greenland [2], [3] although these environments are generally poorly characterized. To date, no acidophilic psychrophiles have been described but psychrotolerant acidophiles have been isolated.

One such psychrotolerant acidophile is Acidithiobacillus ferrooxidans strain SS3 that can grow on Fe2+ and sulfur compounds at 5ºC, although growth is faster at higher temperatures (see figure). This strain has also been tested for bioleaching and has been shown to catalyze metal solubilization from pyrite, arsenopyrite, and chalcopyrite at 5ºC, although the rate was higher at 30 ºC [4].

In cold environments temperature becomes a limiting factor during heap leaching, reducing leaching rates such that the process may become uneconomical. Therefore, a potential biohydrometallurgical use of psychrotolerant acidophiles could be to initiate heap bioleaching in cold environments, to heat up the heap thus increasing the chemical leaching rate, and to prepare for colonisation of other bioleaching species.

References

This article is based on psychrotolerant acidophiles 2006 by Mark Dopson

  1. Kupka et al. (2006) Un-published.
  2. Elberling et al. (2000) J Contam Hydrol 41,225-238.
  3. Langdahl & Ingvorsen (1997) FEMS Microbiol Ecol 23, 275-283.
  4. Dopson et al. (2006) Un-published.
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