Description of two endophytic novel species within the genus Sinomicrobium isolated from a root of Kalidium cuspidatum: Sinomicrobium endophyticum sp. nov. and Sinomicrobium halophytocola sp. nov.

Two bacterial strains, designated M5D2P9 T and M5D2P17 T , were isolated from a root of the halophyte Kalidium cuspidatum in Baotou, Inner Mongolia, China. Phylogenetic trees based on the 16S rRNA gene sequences and core genomes both showed that strains M5D2P9 T and M5D2P17 T formed a stable cluster with Sinomicrobium strains. Both strains shared the highest similarity with Sinomicrobium pectinilyticum 5DNS001 T , with values of 97.7 and 97.9%, respectively. The average nucleotide identity based on blast (ANIb) and digital DNA–DNA hybridization (dDDH) values between the two strains were 88.8 and 39.6%, respectively. The ANIb and dDDH between the two strains and S. pectinilyticum 5DNS001 T were 85.3 and 85.9% and 22.1 and 20.9%, respectively. The predominant isoprenoid quinone of strain M5D2P9 T was menaquinone 6 (MK-6), while that of strain M5D2P17 T was menaquinone 7 (MK-7) and MK-6 as a minor component. The polar lipid profiles of strains M5D2P9 T and M5D2P17 T were composed of phosphatidylethanolamine, unidentified aminolipid and unidentified phospholipid. Based on phenotypic and phylogenetic analyses, these two strains should be considered as two novel species of the genus Sinomicrobium , for which the names Sinomicrobium endophyticum sp. nov. (type strain M5D2P9 T =CGMCC 1.65541 T =JCM 38147 T ) and Sinomicrobium halophytocola sp. nov. (type strain M5D2P17 T =CGMCC 1.65542 T =JCM 38148 T ) are proposed.