POLAROMONAS VACUOLATA GEN-NOV, SP-NOV, A PSYCHROPHILIC, MARINE, GAS VACUOLATE BACTERIUM FROM ANTARCTICA

Several strains of a novel heterotrophic gas vacuolate bacterium were isolated from antarctic marine waters. The results of phylogenetic ana lyses in which 16S ribosomal DNA sequencing was used, coupled with phe notypic tests, indicated that strain 34-P-T (T = type strain) belongs to a new genus and species of the beta subgroup of the Proteobacteria, for which the name Polaromonas vacuolata is proposed. Although the ot her four strains studied probably belong to this new species, DNA-DNA hybridization tests were not conducted. The closest phylogenetic relat ives of P. vacuolata are the photosynthetic nonsulfur purple bacterium Rhodoferax fermentans and the hydrogen autotroph Variovorax paradoxus .