Two marine bacterial strains, KMM 3823(T) and KMM 3836, isolated from a sipuncula (Phascolosoma japonicum), a common inhabitant of Troitsa Bay in the Gulf of Peter the Great (Sea of Japan), were studied. Comparative 16S rRNA gene sequence-based phylogenetic analysis placed these bacteria into a separate branch of the 'Gammaproteobacteria' within members of the genus SHEWANELLA: KMM 3823(T) showed the highest similarity (96.6 %) with Shewanella fidelis. The DNA G+C contents of the two strains studied were 43.0 mol%. The level of DNA homology between these two strains was conspecific (93 %), indicating that they represent a single genospecies. These organisms were greenish-brown, Gram-negative, polarly flagellated, facultatively anaerobic, mesophilic (temperature range 4-30 degrees C), neutrophilic, haemolytic and were able to degrade elastin, gelatin and DNA. They were susceptible to ampicillin, carbenicillin, gentamicin and kanamycin. The predominant fatty acids were characteristic for shewanellas: 13 : 0-i, 15 : 0-i and 16 : 1(n-7); up to 6.7 % of eicosapentaenoic fatty acid, 20 : 5(n-3), was produced during growth at 28 degrees C. Phylogenetic evidence, confirmed by DNA hybridization and phenotypic characteristics revealed that the two bacteria studied constitute a new species, Shewanella waksmanii sp. nov., the type strain of which is KMM 3823(T) (=CIP 107701(T)=ATCC BAA-643(T)).