Photobacterium profundum SS9

This organism is a piezophile, that is it lives under high pressure, having been isolated at a depth of 2500 m. It grows over a broad (90 MPa) pressure range and is amenable to genetic manipulation. Like other Vibrionaceae it has 2 circular chromosomes and a 80 kb plasmid. It encodes two complete operons for F1F0 ATP synthase, one on each chromosome as well as three complete sets of cbb3 cytochrome oxidase genes; the one on chr. 2 was possibly acquired from an aproteobacterium, along with an unusual diheme cytochrome c gene. These findings support the idea that modified electron and proton transport are necessary for metabolic activity at high pressure. Confirmation that SS9 is a true piezophile comes from the observation that several stress-response genes are activated at atmospheric pressure (adapted from PubMed 15746425). (HAMAP: PHOPR)