Host range expansion of Leucobacter holotrichiae: first evidence of mammalian infection and comparative genomic insights

作者：Yong Jian Li, Bei Qi, Shuangyan Cao, Rong Zhang, Li Jiao, Ming Zhou, Jing Cai, Mulong Du, Ke Li, Chen Cheng Xiao, QI Ya · 发表于：Frontiers in Microbiology · 年份：2025 · DOI：10.3389/fmicb.2025.1716137 · 被引用次数：1 · 研究领域：Mycobacterium research and diagnosis、Diphtheria, Corynebacterium, and Tetanus、Aquaculture disease management and microbiota

Leucobacter holotrichiae has previously been identified exclusively in insect hosts, with no reports of its presence in mammals. This study is the first to report the isolation of three L. holotrichiae strains (LH23001, LH23002, and LH23003) from mixed cultures of bovine actinomycotic abscesses in a large-scale dairy farm in Xinjiang, China. Phenotypic analysis revealed that these Gram-positive bacilli are non-spore-forming, non-flagellated, non-hemolytic, non-motile, and capable of biofilm formation. The isolates formed transparent membranous white colonies on modified Gao’s medium and could grow in BHI liquid medium containing 9% NaCl. Phylogenetic analysis based on 16S rRNA gene sequences and average nucleotide identity (ANI) further confirmed that these strains are most closely related to L. holotrichiae , with all strains exhibiting strong biofilm-forming ability. Intraperitoneal infection experiments in mice showed that infection induced pathological changes in multiple tissues: vacuolar degeneration of cardiomyocytes, mild steatosis of hepatocytes, focal necrosis of a small number of lymphocytes in the white pulp of the spleen, extensive granulocyte infiltration in the alveolar walls of lung tissue, and mild edema of renal tubular epithelial cells in the renal cortex. Whole-genome sequencing results indicated that the genome size of these strains ranges from 3.63 to 3.68 Mb with a GC content of 66.8–67.2%. They carry multiple antimicrobial resistance genes and virulenc...