PSYCHROFLEXUS-TORQUIS GEN. NOV., SP. NOV., A PSYCHROPHILIC SPECIES FROM ANTARCTIC SEA-ICE, AND RECLASSIFICATION OF FLAVOBACTERIUM-GONDWANENSE (DOBSON ET-AL. 1993) AS PSYCHROFLEXUS-GONDWANENSE GEN. NOV., COMB. NOV

A group of sea-ice-derived psychrophilic bacterial strains possessing the unusual ability to synthesize the polyunsaturated fatty acids eico sapentaenoic acid (20:5 omega 3) and arachidonic acid (20:4 omega 6) b elong to the Family Flavobacteriaceae (Flexibacter-Bacteroides-Flavoba cterium phylum), according to 16S rRNA sequence analysis. Surprisingly , the isolates were also found to cluster closely to the moderately ha lophilic and psychrotrophic species [Flavobacterium] gondwanense (sequ ence similarity 97.8-98.1%). The whole-cell fatty acid profiles of thi s group and [Flavobacterium] gondwanense were very similar and distinc t from other related flavobacteria. The sea ice strains and [Flavobact erium] gondwanense differed substantially in terms of ecophysiology, p ossibly representing divergent adaptations to sympagic and planktonic marine habitats, respectively. Evidence based on phylogeny and fatty a cid profiles supports the conclusion that the taxa are close relatives distinct from other bacterial groups. It is thus proposed that the se a ice strains represent a novel taxon designated Psychroflexus torquis gen, nov., sp. nov. (type strain ACAM 623(T)) while [Flavobacterium] gondwanense becomes Psychroflexus gondwanense gen, nov., comb. nov.