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

Dissimilatory Fe(III) reduction by Shewanella putrefaciens and related spec ies 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 en zymes 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 fr om MR-1 and other Shewanella strains. The results indicate that NCIMB 400 i s significantly more closely related to the newly identified Shewanella fri gidimarina than to the S. putrefaciens type strain. It is therefore propose d that NCIMB 400 should be reclassified as S. frigidimarina.