PSYCHROSERPENS BURTONENSIS GEN-NOV, SP-NOV, AND GELIDIBACTER ALGENS GEN-NOV, SP-NOV, PSYCHROPHILIC BACTERIA ISOLATED FROM ANTARCTIC LACUSTRINE AND SEA-ICE HABITATS

Psychrophilic, yellow-pigmented, seawater-requiring bacteria isolated from the pycnocline of meromictic Burton Lake and from sea ice cores o btained in the Vestfold Bills (68 degrees S, 78 degrees E) in eastern Antarctica were characterized. Phenotypic analysis showed that the str ains isolated formed two distinct taxa. The first taxon included nonmo tile, nutritionally fastidious strains that were isolated from the pyc nocline of Burton Lake. The cells of these strains were morphologicall y variant, ranging from vibrioid to ring shaped to coiled and filament ous; in addition, the strains were unable to metabolize carbohydrates or polysaccharides and had DNA G+C contents of 27 to 29 mol%. The stra ins of the second taxon, which were isolated from sea ice cores and fr om ice algal biomass, were saccharolytic, exhibited rapid gliding moti lity, were rodlike to filamentous, and had DNA G+C contents of 36 to 3 8 mol%. A 16S ribosomal DNA (rDNA) sequence analysis revealed that the two Antarctic taxa formed related but distinct lineages within the [F lexibacter] maritimus rRNA branch of the family Flavobacteriaceae. The levels of 16S rDNA sequence similarity between the taxa were 90.5 to 91.3%, while the levels of similarity to other members of the [F.] mar itimus rRNA branch were 85 to 90%. The whole-cell lipid profiles of th e Antarctic strains were mainly comprised of branched and unbranched m onounsaturated C-15 to C-17 fatty acids. The presence of significant l evels of the lipids a15:1 omega 10c and a17:1 omega 7c appeared to be useful biomarkers for the new Antarctic taxa and for differentiating t hese organisms from ether members of the family Flavobacteriaceae. On the basis of polyphasic taxonomic data we propose that the new taxa ar e novel bacterial species designated Psychroserpens burtonensis gen. n ov., sp, nov. (type strain, ACAM 188) and Gelidibacter algens gen. nov ., sp. nov. (type strain, ACAM 536).