Sphingobium paulinellae sp nov and Sphingobium algicola sp nov., isolated from a freshwater green alga Paulinella chromatophora

Abstract

Two Gram-stain-negative, aerobic, catalase-and oxidase-positive, yellow-pigmented bacteria, designated strains Pch-B (T) and Pch-E (T), were isolated from a green alga Paulinella chromatophora. Both strains were motile short rods with a flagellum and optimally grew at pH 6.0-7.0, 25-30 degrees C and 0-1% NaCl. They contained ubiquinone-10 as the major quinone, spermidine as the major polyamine, C-16 : 0,C- C-14 : 0 2-OH and summed features 3 (comprising C-16 : 1 omega 7c and/or C-16 : 1 omega 6c) and 8 (comprising C-18 : 1 omega 7c and/or C-18 : 1 omega 6c) as the major fatty acids and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidyl-N-methylethanolamine, two sphingoglycolipids and phosphatidylcholine as the major polar lipids. DNA G+ C contents of strains Pch-B (T) and Pch-E-T were 61.4 and 63.9 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strains Pch-B (T) and Pch-E (T) formed a phylogenic lineage with Sphingobium limneticum 301(T). Strains Pch-B (T) and Pch-E (T) had a 99.86% 16S rRNA gene sequence similarity and their DNA-DNA hybridization (DDH) relatedness value was 40.6 %. Strains Pch-B (T) and Pch-E (T) were most closely related to S. limneticum 301 (T) with 99.93 and 99.76% 16S rRNA gene sequence similarities, respectively and the DDH values between strains Pch-B T and Pch-E (T) and the type strain of S. limneticum were 43.3 and 32.1 %, respectively. In conclusion, strains Pch-B T and Pch-E (T) represent novel species of the genus Sphingobium, for which the names Sphingobium paulinellae sp. nov. and Sphingobium algicola sp. nov. are proposed, respectively. The type strains of S. paulinellae and S. algicola are Pch-B T (= KACC 19283 T = JCM 32054 T) and Pch-E T (= KACC 19284 (T) = JCM 32055 (T)), respectively.