Psychromonas profunda sp. nov., a psychropiezophilic bacterium from deep Atlantic sediments.

A psychropiezophilic bacterium, strain 2825T (=LMG 21260T =JCM 11437T), isolated from deep Atlantic sediments at a depth of 2770 m and a temperature of 2 degrees C, was found by polyphasic analysis to represent a novel species of the genus Psychromonas, Psychromonas profunda sp. nov. It is a strict psychrophile and a moderate piezophile, whose degree of piezophily is increased markedly when the temperature is raised to 10 degrees C. The piezophily of P. profunda is intermediate between that of the type species, Psychromonas antarctica, which is not piezophilic, and that of Psychromonas kaikoae, which is an obligate piezophile.

Moritella profunda sp. nov. and Moritella abyssi sp. nov., two psychropiezophilic organisms isolated from deep Atlantic sediments.

Strains 2674T (=LMG 21259T =JCM 11435T) and 2693T (=LMG 21258T =JCM 11436T) were isolated from Atlantic sediments at a temperature of 2 degrees C and a depth of 2815 m off the West African coast. Polyphasic evidence indicates that the two strains belong to the genus Moritella and represent distinct species, for which the names Moritella profunda sp. nov. (for strain 2674T) and Moritella abyssi sp. nov. (for strain 2693T) are proposed. The moderate piezophily of the two organisms is intermediate between that of the type species, Moritella marina, which is not piezophilic, and Moritella yayanosii, an obligate piezophile. Both are strict psychrophiles with slightly different cardinal temperatures: at 0.1 MPa, maximal growth rates are observed at 2 degrees C (M. profunda) and 4 degrees C (M. abyssi) with maximum temperatures of 12 degrees C (M. profunda) or 14 degrees C (M. abyssi). The optimal pressure is lower than that at the site of isolation, and raising the temperature to 10 degrees C makes the organisms more piezophilic.