Cae Coch ore body is responsible for acid mine drainage from the abandoned Cae Coch sulfur mine and Trefriw Wells Spa water. These waters are extremely acidic and contain elevated ferrous iron concentration and low concentrations of other transition metals. Trefriw Wells Spa water has been used as a "natural" remedy for iron-deficiency for over 100 years. The current study examined biogeochemical processes related to weathering of the pyrite ore responsible for this water, focusing on fundamental and applied areas of acidophile microbiology.
Concentration of ferrous iron in the spa water is declining over time, so a protocol for synthesising a concentrated analogue was established to possibly supplement the product in future years. This process used the same general processes as the natural product (oxidative dissolution of pyrite catalysed by chemolithotrophic acidophiles), resulting in liquor containing ∼x10 the ferrous iron concentration of the original water. The viability of two neutrophilic bacteria in the acidic spa water (strains of Dermacoccus nishinomiyaensis and
Kocuria marina), isolated from Spatone sachets was also investigated. Isolates exhibited rapid morbidity, with no viable bacteria isolated 24 hours after addition to the spa water. Bacterial communities at the site were examined by a combined molecular and cultivation-based approach; some bacteria not previously characterised were identified and, for some, isolated from waters samples from the Trefriw Wells Spa. These included the proposed novel species "Acidocella acidivorans" which was studied in detail, validated novel species
Acidocella aromatica and validated novel genus and species Acidithrix ferrooxidans. All of these heterotrophic acidophiles catalysed the dissimilatory reduction of ferric iron. Atx. ferrooxidans also catalysed the dissimilatory oxidation of ferrous iron, a key process in Trefriw water formation. This ability, and streamer-forming growth in flowing water was harnessed in a continuous flow bioreactor, proposed as a component module of a system to
remediate acidic, iron-rich mine waters. Each characterised novel bacterial species has characteristics that are potentially useful in biotechnologies such as bioremediation.