Extraction of DNA from acidic, hydrothermally modified volcanic soils

Acidic soils for microbial diversity studies were collected from Devil's Kitchen, a fumarolic field on Mt Hood, USA. The very dense soils, which contain clay and other minerals, are derived from andesitic and dacitic rocks altered by volcanic heat and acidic, sulfur-rich hydrothermal steam. An initial attempt to extract biomass DNA using a mechanical-based cell lysis protocol was ineffective. However, by using various other protocols, DNA was successfully extracted, leading to the identification of several acidophilic Mt Hood extremophiles. The results emphasise the importance of testing different extraction procedures when dealing with apparently intractable samples.