Methylophaga pinxianii sp. nov., isolated from the Mariana Trench

Two strains, TMB456(T) and TMB1265, were isolated from different locations in the Mariana Trench. Analysis of the 16S rRNA gene and genomic rRNA sequences indicated that they were from the same novel species and were affiliated with the genus Methylophaga of the class Gammaproteobacteria. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the most closely related validly published species were Methylophaga muralis Kr3(T) (98.1% similarity) and Methylophaga nitratireducenticrescens JAM1(T) (97.3% similarity). Digital DNA-DNA hybridization values of TMB456(T) with M. muralis Kr3(T) and M. nitratireducenticrescens JAM1(T) were <25 %. The average nucleotide identity value between strain TMB456(T) and M. muralis Kr3(T) was 80.9%. The genomic DNA G+C contents of strains TMB456(T) and TMB1265 were both 44.9 mol %. Strains TMB456(T) and TMB1265 could grow at 4-37 degrees C (optimum at 20-28 degrees C), at pH 3-10 (optimum at pH 7-9) and in the presence of 0-10 % (w/v) NaCl (optimum at 0-1 %). Cells of strains TMB456(T) and TMB1265 were Gram-negative rods (0.3-0.6 mu mx0.7-1.3 mu m). Chemotaxonomic analysis showed that ubiquinone 8 was the sole quinone produced by strain TMB456(T) and that the major cellular fatty acids were iso-C-16:0, summed feature 3 (C1(6:1) omega 7c and/or C-16:1 omega 6c) and summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c). The polar lipid profile of this strain included phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphoglycolipids and two unidentified polar lipids. Based on the phenotypic, chemotaxonomic and molecular features, strains TMB456(T) and TMB1265 belong to a novel species within the genus Methylophaga, for which the name Methylophaga pinxianii sp. nov. is proposed. The type strain is TMB456(T) (=KCTC 82622(T)= MCCC 1K05898(T)).