Shewanella affinis sp. nov., isolated from marine invertebrates

Four marine bacterial strains, designated KMM 3587T, KMM 3586, KMM 3821 and KMM 3822, were isolated from the sipuncula Phascolosoma japonicum, a common inhabitant of Troitza Bay in the Gulf of Peter the Great (Sea of Japan region), and from an unidentified hydrocoral species collected in Makarov Bay (Iturup Islands), Kuril Islands, North-West Pacific Ocean. The strains were characterized to clarify their taxonomic position. 16S rRNA gene sequences of KMM 3587T and KMM 3586 indicated 99% similarity to Shewanella colwelliana. Despite such a high level of 16S rRNA gene sequence similarity, DNA-DNA hybridization experiments demonstrated only 45-52% binding with DNA of S. colwelliana ATCC 39565T. The DNA G+C contents of the novel strains were 45 mol% and the shared level of DNA hybridization was conspecific (81-97%), indicating that they represent a single genospecies. The novel strains were mesophilic (able to grow at 10-34 degrees C), neutrophilic and haemolytic, and able to degrade gelatin, casein and Tween 20, 40 and 80, but not starch, agar, elastin, alginate or chitin. The major fatty acids were i13 : 0, i15 : 0, 16 : 0, 16 : 1omega7 and 17 : 1omega8 (68.9% of total). The major isoprenoid quinones were Q7 (47-62%) and Q8 (26-47%). Eicosapentaenoic acid was produced in minor amounts. Based on these data, the strains are assigned to a novel species, Shewanella affinis sp. nov. (type strain KMM 3587T=CIP 107703T=ATCC BAA-642T).