Psychromonas ingrahamii sp. nov., a novel gas vacuolate, psychrophilic bacterium isolated from Arctic polar sea ice

Abstract

A gas vacuolate bacterium, designated strain 37T, was isolated from a sea ice core collected from Point Barrow, Alaska, USA. Cells of strain 37T were large (6–14 μm in length), rod-shaped, contained gas vacuoles of two distinct morphologies, and grew well at NaCl concentrations of 1–10 % and at temperatures of −12 to 10 °C. The DNA G+C content was 40 mol%. Whole-cell fatty acid analysis showed that 16 : 1ω7c comprised 67 % of the total fatty acid content. Phylogenetic analysis of 16S rRNA gene sequences indicated that this bacterium was closely related to members of the genus Psychromonas, with highest sequence similarity (96.8 %) to Psychromonas antarctica. Phenotypic analysis differentiated strain 37T from P. antarctica on the basis of several characteristics, including cell morphology, growth temperature range and the ability to hydrolyse polymers. DNA–DNA hybridization experiments revealed a level of relatedness of 37 % between strain 37T and P. antarctica, providing further support that it represents a distinct species. The name Psychromonas ingrahamii sp. nov. is proposed for this novel species. The type strain is 37T (=CCUG 51855T=CIP 108865T).