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 M5D2P9T and M5D2P17T, 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 M5D2P9T and M5D2P17T formed a stable cluster with Sinomicrobium strains. Both strains shared the highest similarity with Sinomicrobium pectinilyticum 5DNS001T, 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 5DNS001T were 85.3 and 85.9% and 22.1 and 20.9%, respectively. The predominant isoprenoid quinone of strain M5D2P9T was menaquinone 6 (MK-6), while that of strain M5D2P17T was menaquinone 7 (MK-7) and MK-6 as a minor component. The polar lipid profiles of strains M5D2P9T and M5D2P17T 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 M5D2P9T=CGMCC 1.65541T=JCM 38147T) and Sinomicrobium halophytocola sp. nov. (type strain M5D2P17T=CGMCC 1.65542T=JCM 38148T) are proposed.