Hephaestia mangrovi sp. nov., a novel endophytic bacterium isolated from Aegiceras corniculatum

Abstract

A Gram-stain-negative, aerobic, motile, rod-shaped bacterium, designated CMS5P-6^T, was isolated from a surface-sterilized bark of Aegiceras corniculatum collected from Guangxi Zhuang Autonomous Region, PR China, and investigated by a polyphasic approach to determine its taxonomic position. Strain CMS5P-6^T was found to grow optimally with 0-1 % (w/v) NaCl, at 30 °C and pH 6.0-7.0. Substrate mycelia and aerial mycelia were not formed, and no diffusible pigments were observed on the media tested. Phylogenetic analysis showed that strain CMS5P-6^T showed high 16S rRNA gene sequence similarity of 96.7 % to Hephaestia caeni DSM 25527^T and Sphingomonas colocasiea CC-MHH0539^T. The average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values between strain CMS5P-6^T and H. caeni DSM 25527^T were 78.0, 21.7 and 70.8 %, respectively. The average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values between strain CMS5P-6^T and S. colocasiea JCM 31229^T were 74.0, 19.9 and 61.4 %, respectively. Phylogenomic analyses based on genome sequences showed that strain CMS5P-6^T and H. caeni DSM 25527^T formed a distinct cluster within the family Sphingomonadaceae and far away from S. colocasiea JCM 31229^T. The DNA G+C content of strain CMS5P-6^T was determined to be 65.6 mol%. The cell-wall peptidoglycan was found to contain meso-diaminopimelic acid as the diagnostic diamino acid and ubiquinone Q-10 was identified as the respiratory lipoquinone. The polar lipids were found to comprise diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, sphingoglycolipid and two unidentified aminolipids, and the major fatty acids were identified as C_{18 : 1} ω7c, C_{19 : 0} cycloω8c and C_{16 : 0}. On the basis of phylogenetic, genomic, chemotaxonomic and phenotypic data, strain CMS5P-6^T can be concluded to represent a novel species of the genus Hephaestia, for which the name Hephaestia mangrovi sp. nov. is proposed. The type strain is CMS5P-6^T (=JCM 33125^T=CGMCC 1.13868^T).