Ferroplasma acidarmanus lives as a biofilm directly in the acid streams[1][2]. I'm not sure what the pH is in those specific areas, but it's very low (below 0).

Ferroplasma acidarmanus lives as a biofilm directly in the acid streams[1][2]. I'm not sure what the pH is in those specific areas, but it's very low (below 0). Compared to abiotic leeching of the iron pyrite in the mine, Ferroplasma greatly speeds up the reaction by using ferric iron as a catalyst: 4Fe2+ + O2 + 4H+ → 4Fe3+ + 2H2O FeS2 + 14Fe3+ + 8H2O → 15Fe2+ + 2SO42- + 16H+ The natural pyrite ore does not produce the extreme acid runoff. The problem starts when we mine out an area and oxygen is introduced, which is used to create Fe3+. This allows a much more efficient conversion of pyrite into a lot of acid. This extremophile excretes pure sulfuric acid. [1] https://microbewiki.kenyon.edu/index.php/File:Ferroplasma_1.JPG https://microbewiki.kenyon.edu/index.php/File:Ferroplasma_1.... [2] https://digital.wwnorton.com/ebooks/epub/microbio4/OEBPS/images/sfmb4e_1940.jpg https://digital.wwnorton.com/ebooks/epub/microbio4/OEBPS/ima...