Curtobacterium salicis sp. nov., isolated from willow tree stems in Washington state

Curtobacterium sp. strain WW7 is a Gram-positive, non-motile, orange rod-shaped bacterium isolated from branches of wild willow (Salix sitchensis) trees. The WW7^T strain has optimum growth in the temperature range between 25 and 30 °C, a pH range of 6-7.7, and tolerates up to 5.5% (w/v) of NaCl. The genome sequencing of strain WW7^T revealed a genome size of approximately 3.8 Mbp and a G + C content of 71.3 mol%. The phylogenomic analyses support the WW7^T affiliation to a novel Curtobacterium lineage, with Curtobacterium herbarum being the closest type-strain. Chemotaxonomic analysis indicates that the carbon sources assimilation profile of strain WW7^T was similar to the type strains, i.e. Curtobacterium luteum, Curtobacterium albidum, and Curtobacterium flaccumfaciens, while no assimilation of the organic acids succinate, alpha-ketobutyrate, mono methyl-succinate, and lactate was observed. Finally, fatty acid methyl ester analysis identifies anteiso-C_15:0 and anteiso-C_17:0 as major cellular fatty acids which is a common feature for members of the Curtobacterium genus. Based on the results of phylogenomic and chemotaxonomic analyses, strain WW7^T represents a novel Curtobacterium lineage, for which the name Curtobacterium salicis sp. nov. is proposed. The type strain is WW7^T (DSM 34805^T-NRRL B-68078^T).