The Aquificaceaefamily are bacteria that live in harsh environmental settings such as hot springs, sulfur pools, and hydrothermal vents. Although they are true bacteria as opposed to the other inhabitants of extreme environments, the Archaea, Aquificaceae genera are an early phylogenetic branch.1
References
^ Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms (11th ed. ed.), Prentice Hall. ISBN 0-13-144329-1.
Reysenbach A-L, Phylum BI (2001) Aquificae phy. nov. In: Boone DR, Castenholz RW (eds) Bergey’s Manual of Systematic Bacteriology. Springer-Verlag, Berlin, 2nd edn., pp. 359–367