Shewanella saliphila sp. nov., Shewanella ulleungensis sp. nov. and Shewanella litoralis sp. nov., isolated from coastal seawater

Abstract

Three Gram-negative, non-spore-forming, rod-shaped and motile bacterial strains, designated MMS16-UL250T, MMS16-UL253T and MMS16-UL482T, were isolated from coastal seawater and subjected to taxonomic characterization. All isolates grew at 4-30 °C (optimum, 25 °C), at pH 6-10 (pH 7) and in the presence of up to 8 % NaCl (2.5-4.5 %). The 16S rRNA gene sequence similarities between the three isolates and Shewanella algicola St-6T, the closest species, were 98.1-99.2 %, and those among the isolates were 98.5-99.0 %. In the phylogenetic tree, MMS16-UL250T formed a cluster with S. algicola St-6T, but the DNA-DNA relatedness between the two strains was 28.8±1.5 %, thus confirming their separation at species level. The other two strains formed separate phylogenetic lines respectively. The main quinones for all strains were Q-7, Q-8, MK-7 and MMK-7, which is typical for Shewanella. The major polar lipids of all strains were phosphatidylglycerol and phosphatidylethanolamine, and the common major fatty acid was a summed feature consisting of C16 : 1ω7c and/or C16 : 1ω6c while the proportions varied among the three strains. The DNA G+C contents of the strains also varied between 42.1 and 43.7 mol%. Phenotypic properties distinguished each strain from S. algicola as well as from one another. Based on the polyphasic analysis, each strain is considered to represent a novel species of Shewanella, for which the names Shewanellasaliphila sp. nov. (type strain, MMS16-UL250T=KCTC 62131T=JCM 32304T), Shewanella ulleungensis sp. nov. (type strain, MMS16-UL253T=KCTC 62130T=JCM 32305T) and Shewanella litoralis sp. nov. (type strain, MMS16-UL482T=KCTC 62129T=JCM 32306T) are proposed.