Discovery of a new bacterium, Microbacterium betulae sp. nov., in birch wood associated with hypersensitivity pneumonitis in woodworkers

A Gram‐positive, aerobic, rod‐shaped mesophilic bacterium was isolated from birch wood, referred to as the AB strain. Allergological tests suggest that this strain may cause allergic alveolitis in sawmill workers. Employing a polyphasic taxonomic approach, the AB strain's 16S rRNA gene sequence showed high similarity to Microbacterium barkeri and M. oryzae, with 97.25% and 96.91%, respectively, a finding supported by rpoB and gyrB sequence analysis. Further genome sequence comparison with the closely related M. barkeri type strain indicated a digital DNA–DNA hybridization value of 25.5% and an average nucleotide identity of 82.52%. The AB strain's cell wall peptidoglycan contains ornithine, and its polar lipids comprise diphosphatidylglycerol, phosphatidylglycerol, and unidentified glycolipids. Its major fatty acids include anteiso C15:0, anteiso C17:0, and iso C16:0, while MK‐10 is its predominant respiratory quinone. Comprehensive analysis through 16S rRNA, whole‐genome sequencing, phenotyping, chemotaxonomy, and MALDI‐TOF MS profiling indicates that the AB strain represents a new species within the Microbacterium genus. It has been proposed to name this species Microbacterium betulae sp. nov., with ABT (PCM 3040T = CEST 30706T) designated as the type strain. Through the use of 16S rRNA and whole‐genome sequence analysis, along with phenotyping, chemotaxonomy, and MALDI‐TOF MS profiling, a strain isolated from birch wood has been identified as a new species. This novel species falls within the Microbacterium genus and has been proposed to be named Microbacterium betulae sp. nov.