Summary
A group of pigmented, psychrophilic, strictly aerobic chemoheterotrophs isolated from sea-ice cores collected from coastal areas of eastern Antarctica was found to represent a novel 16S rRNA lineage within the gamma subclass of the Proteobacteria, adjacent to the genus Alteromonas. The isolates are motile, Gram-negative, rod-shaped cells, which are psychrophilic and slightly halophilic and possess an absolute requirement for seawater. Differences in phenotypic characteristics and DNA–DNA hybridization indicated the isolates formed two distinct taxa which have DNA G+C contents of 44–46 mol% and 40 mol%, respectively. Whole-cell fatty acid profiles of the isolates were however very similar and included 16:1w7c, 18:1w7c, 16:0 and 17:1w8c as the major fatty acid components. Overall, sufficient differences exist to distinguish the sea-ice strains from currently recognized bacterial genera. It is proposed that the sea-ice strains represent a new genus, Glaciecola, which contains two spe c ies, Glaciecola punicea gen. nov., sp. nov. (ACAM 611T) and Glaciecola pallidula gen. nov., sp. nov. (ACAM 615T).