Multiphase study of denials gram bacteria atypical of Antarctic origin

Three strains of psychrotrophic bacteria isolated from Antarctic coastal marine
environments were studied to determine their taxonomic position. These bacteria
were gram negative rods, facultatively anaerobic, and motile by means of a
single polar flagellum. None of the bacterial isolates had an Na+ requirement.
Only one of the strains was capable of producing H2S from thiosulfate (S203-2).
DNA-DNA hybridization experiments showed that the isolates formed two related
groups clearly different from Shewanella putrefaciens. Their DNA base content
was 42 and 38 mol% G+C respectively. The fatty acid profiles of the bacterial
isolates were found to be similar to the profiles of other Shewanella species.
A1l of the strains contained (both) ubiquinones and menaquinones as occur with
members of the genus Shewanella. Methylmenaquinones were also found. 16S rRNA
gene anaIysis confirmed that isolated strains belonged to the genus Shewanella
and were phylogenetically related to the newly identified Shewanella
frigidimarina (99.5 % sequence similarity). The results of the polyphasic
taxonomic study allowed the conclusion that the three isolates must be
classified within the genus Shewanella.