Acidophilic microbes in a tuscan acidic mine drainage and potential application of Euglena mutabilis in bioremediation.

Many studies have illustrated the potential role of eukaryotes in bioremediation of Acidic Mine Drainage (AMD), especially algae and fungi that inhabit this environment. It is largely reported that algae can generate alkalinity and reduce level of heavy metals, directly and indirectly. In this study, two abandoned mines were analysed: Pollone Mine and Monte Arsiccio Mine (Lucca, Italy). Here, pyrite dissolution that generates acidic drainage is accelerated by the activity of prokaryotes. With PCR amplification (16S rDNA), these bacteria were detected: Acidithiobacillus ferrooxidans, Acidithiobacillus ferrivorans, Sulfobacillus sp., Leptospirillum ferrooxidans and Leptospirillum sp. Moreover, inside and outside mines, some forms of protists were found. With molecular method (PCR amplification of the 18S rDNA) the ciliated protozoan Oxytricha acidotolerans was identified and with morphological approach an alga was identified as Euglena mutabilis. This last protist is a typical inhabitant of acidic environment and it can accumulate metals such as Fe and As; furthermore, a specific detoxification pathway for As was found. A biological and passive method of remediation is proposed: exploiting the endemic alga E. mutabilis, it's possible to promote the alkalinity of effluents and reduce the concentration of some heavy metals.