Pusillimonas maritima sp. nov., isolated from surface seawater

Abstract

Two Gram-stain-negative, short rod-shaped and non-flagellated strains, designated 17-4A^T and L52-1-41, were isolated from the surface seawater of the Indian Ocean and South China Sea, respectively. The 16S rRNA genes of the two strains shared sequence similarity of 99.45 %. Strain 17-4A^T shared the highest 16S rRNA gene similarity of 98.02 % with Pusillimonas caeni EBR-8-1^T, followed by Pusillimonas noertemannii BN9^T (97.47 %), Pusillimonas soli MJ07^T (96.93 %), Parapusillimonas granuli Ch07^T (96.68 %), Pusillimonas ginsengisoli DCY25^T (96.65 %), Eoetvoesia caeni PB3-7B^T (96.63 %), Paracandidimonas caeni 24^T (96.34 %), Castellaniella defragrans 54Pin^T (96.28 %) and Pusillimonas harenae B201^T (96.05 %). L52-1-41 shared the highest 16S rRNA gene similarity of 97.74 % with Pusillimonas caeni EBR-8-1^T, followed by Pusillimonas noertemannii BN9^T (97.47 %), Pusillimonas soli MJ07^T (96.65 %), Parapusillimonas granuli Ch07^T (96.41 %), Pusillimonas ginsengisoli DCY25^T (96.37 %), Eoetvoesia caeni PB3-7B^T (96.35 %), Pusillimonas harenae B201^T (96.28 %), and Paracandidimonas caeni 24^T (96.06 %). The results of phylogenetic analyses indicated that 17-4A^T and L52-1-41 formed a stable, distinct and highly supported lineage affiliated to the genus Pusillimonas. The results of the digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses indicated that they represented a single species. They featured similar genomic DNA G+C contents of 53.2-53.4 mol%. Activities of catalase and oxidase were negative for both strains. The fatty acids patterns of 17-4A^T and L52-1-41 were most similar, mostly comprised of C_{16 : 0}, C_{17 : 0}cyclo, C_{18 : 0}, C_{18 : 1}ω9c and summed feature 8 (C_{18 : 1}ω7c and/or C_{18 : 1} ω6c). The major polar lipids of the two strains were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and unidentified aminolipids. The respiratory quinone of the two strains was Q-8. Hence, on the basis of the phenotypic, chemotaxonomic and genotypic data presented in this study, we proposed the classification of both strains as representatives of a novel species named Pusillimonas maritima sp. nov., with the type strain 17-4A^T (=MCCC 1A12670^T=KCTC 62121^T=NBRC 113794^T), and another strain L52-1-41 (=MCCC 1A05046=KCTC 52313).

Keywords: Pusillimonas maritima; polyphasic taxonomy; surface seawater.