Psychrobacter submarinus sp. nov. and Psychrobacter marincola sp. nov., psychrophilic halophiles from marine environments.

Two novel psychrophilic, halophilic, Psychrobacter-like bacteria, strains KMM 225T and KMM 277T, were isolated from sea water and the internal tissues of an ascidian Polysyncraton sp. specimen, respectively, and characterized using a polyphasic approach, which included phenotypic, genotypic, chemotaxonomic and phylogenetic analyses. The novel marine isolates were Gram-negative, aerobic, coccoid, oxidase- and catalase-positive, non-pigmented, non-motile, psychrophilic and halophilic and they utilized a restricted spectrum of carbon sources. Strains KMM 225T and KMM 277T required sea water or sodium ions for growth and were tolerant of up to 12-15% (w/v) NaCl. Growth of strains KMM 225T and KMM 277T was observed at 4-35 and 7-35 degrees C, respectively. The DNA G+C contents of KMM 225T and KMM 277T were respectively 46-8 and 50.7 mol %. Comparison of almost complete 16S rDNA sequences of strains KMM 225T and KMM 277T revealed that both strains were phylogenetically most closely related to each other (99.9% sequence similarity) and slightly less related to Psychrobacter glacincola, with 97.2 and 97.8% similarity, respectively. DNA-DNA reassociation between KMM 225T and KMM 277T revealed 15% similarity, whereas similarity to other Psychrobacter species was 14-25%. Strains KMM 225T and KMM 277T differed from one another in their growth temperature, organic substrate utilization, antibiotic sensitivity and DNA G+C content. Both strains examined could be distinguished from all previously described Psychrobacter species by their physiological, genotypic and phylogenetic characteristics. On the basis of the physiological and molecular properties of the novel isolates, the names Psychrobacter submarinus sp. nov. (type strain KMM 225T = DSM 14161T) and Psychrobacter marincola sp. nov. (type strain KMM 277T = DSM 14160T) are proposed.