Microbacterium salsuginis sp. nov., a halotolerant actinobacterium with antimicrobial activity

A novel Gram- staining- positive actinobacterium with antimicrobial activity, designated CFH 90308(T), was isolated from the sediment of a salt lake in Yuncheng, Shanxi, south-western China. The isolate exhibited the highest 16S rRNA gene sequence similarities to Microbacterium yannicii G72(T), Microbacterium hominis NBRC 15708(T) and Microbacterium xylanilyticum S3- E-T (98.5, 98.4 and 98.2 %, respectively), and formed a separate clade with M. xylanilyticum S3- E-T in phylogenetic trees. The strain grew at 15-40 degrees C, pH 6.0-8.0 and could tolerate NaCl up to a concentration of 15 % (w/v). The whole genome of strain CFH 90308(T) con-sisted of 4.33 Mbp and the DNA G+C content was 69.6 mol%. The acyl type of the peptidoglycan was glycolyl and the whole- cell sugars were galactose and mannose. The cell-wall peptidoglycan mainly contained alanine, glycine and lysine. The menaqui-nones of strain CFH 90308(T) were MK- 12, MK- 13 and MK- 11. Strain CFH 90308(T) contained anteiso- C-15:0, anteiso- C-17:0, iso- C(16:0)and iso- C-15:0 as the predominant fatty acids. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between CFH 90308(T) and the other species of the genus Microbacterium were found to be low (ANIb <81.3 %, dDDH <25.6 %). The secondary metabolite produced by strain CFH 90308(T) showed antibacterial activities against Bacillus subtilis,Pseudomonas syringae, Aeromonas hydrophila and methicillin- resistant Staphylococcus aureus. Based on genotypic, phenotypic and chemotaxonomic results, the isolate is considered to represent a novel species of the genus Microbacterium, for which the name Microbacteriumsalsuginis sp. nov. is proposed. The type strain is CFH 90308(T) (=DSM 105964(T)=KCTC 49052(T))