Shewanella Pacifica Sp. Nov., a Polyunsaturated Fatty Acid-producing Bacterium Isolated from Sea Water

Six marine bacterial strains, KMM 3597T, KMM 3775, KMM 3590, KMM 3772, KMM 3605 and KMM 3601, that produce polyunsaturated fatty acids were isolated from sea water samples collected from different locations and depths in Chazhma Bay (Sea of Japan, Pacific Ocean) and characterized to clarify their taxonomic position. The DNA G+C contents of these strains were 39.5-40.3 mol%. The level of DNA hybridization between these strains was conspecific (83-96%), indicating that they represent a single genospecies. 16S rRNA gene sequence-based phylogenetic analysis of the novel strains revealed that Shewanella japonica KMM 3299T was the closest relative (99% similarity). However, DNA-DNA hybridization experiments demonstrated only 45-50% binding with DNA of S. japonica. The novel organisms grew between 4 and 33 degrees C, were neutrophilic and haemolytic, and were able to degrade starch, gelatin, agar and Tween 80. The predominant fatty acids were (%+/-sd): i13 : 0 (9.3+/-1.1); i15 : 0 (33.9+/-1.5); 16 : 0 (8.9+/-1.6); and 16 : 1omega7 (14.8+/-1.1). The fatty acid 20 : 5omega3, formed at 28 degrees C, was present at up to 5.3% total fatty acids. The major isoprenoid quinones were Q7 (21-41%) and Q8 (50-59%). The phylogenetic, genetic and physiological properties of the six strains placed them within a novel species, Shewanella pacifica sp. nov., the type strain of which is R10SW1T (=KMM 3597T=CIP 107849T).