Two actinobacterial strains, YJYP 303T and YZYP 518, were isolated from two species of halophytes collected from the southern edge of the Gurbantunggut Desert. Cells were Gram-stain-positive, aerobic, short rods and without flagella. Growth of the two strains was found to occur at 4-44 °C, pH 6.0-12.0 and in the presence of up to 15 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two strains are associated with members of the genus Microbacterium. In the phylogenetic tree, the two strains shared a clade with Microbacterium halotolerans YIM 70130T (97.58 % 16S rRNA gene sequence identity) and Microbacterium populi KCTC 29152T (96.54 %). The average nucleotide identity values of strain YJYP 303T and YZYP 518 to M. halotolerans YIM 70130T were determined to be 79.97 and 80.03 %, respectively. The genomic DNA G+C contents of strains YJYP 303T and YZYP 518 were 69.72 and 70.57 %, respectively. The major fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The predominant respiratory quinones was MK-11, followed by MK-10 and MK-12. The muramic acid type of peptidoglycan was N-glycolyl. The whole-cell sugars were mannose, ribose, rhamnose, glucose, galactose and two unidentified sugars. The cell-wall amino acids were glutamic acid, ornithine, glycine and alanine. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, an unidentified phospholipid and an unidentified glycolipid. On the basis of the evidence presented in this study, strains YJYP 303T and YZYP 518 are characterized as members of a novel species in the genus Microbacterium, for which the name Microbacteriumhalophytorum sp. nov. is proposed. The type strain is YJYP 303T (=CGMCC 1.16264T=KCTC 49100T).
Keywords: Gurbantunggut desert; Microbacterium halophytorum sp. nov.; endophytic actinobacterium; halophytes; polyphasic taxonomy.