Phylogeny of marine and freshwater Shewanella: reclassification of Shewanella putrefaciens NCIMB 400 as Shewanella frigidimarina.

Dissimilatory Fe(III) reduction by Shewanella putrefaciens and related species has generated considerable interest in biochemical characterization of the pathways for anaerobic electron transfer in this organism. Two strains, MR-1 and NCIMB 400, have been extensively used, and several respiratory enzymes have been isolated from each. It has become apparent that significant sequence differences exist between homologous proteins from these strains. The 16S rRNA from NCIMB 400 was sequenced and compared to the sequences from MR-1 and other Shewanella strains. The results indicate that NCIMB 400 is significantly more closely related to the newly identified Shewanella frigidimarina than to the S. putrefaciens type strain. It is therefore proposed that NCIMB 400 should be reclassified as S. frigidimarina.