Photo credit: T. Amo et al, Archaea 2002. Bar=1um (micron).

Pyrobaculum arsenaticum DSM 13514 was the first hyperthermophile to be isolated using arsenate as a terminal electron acceptor (Huber et al, 2000). Cultures grown on arsenate (up to 20 mM) with either thiosulfate or L-cysteine produce yellow arsenic-sulfide minerals identified as realgar (As2S2), which are also observed in hot spring environments (Floroiu et al., 2004). The genome sequence of P. arsenaticum will provide important insight into the diversity of genes and enzymes involved in arsenate respiration, as well as those used in selenate and sulfur metabolism.