Whole-genome analysis and fermentation-metabolite profiling of a cellulolytic Arthrobacter sp. FMD isolated from forest musk-deer faeces

Most studies on the intestinal microbiota of the forest musk deer (Moschus berezovskii) are based on community-level sequencing, and functional characterisation of individual strains is rare. Here we isolated strain FMD from deer faeces by selecting on CMC-Na as the sole carbon source; it utilises xylose, trehalose and fructose and is positive for urease and the methyl-red test. Whole-genome sequencing yielded a 4.05 Mb chromosome (GC 64.1%, four contigs, 3 726 CDS), and phylogenomic analyses (20 core genes, ANI and SNP tree) placed the isolate in the genus Arthrobacter ; the strain was designated Arthrobacter sp . FMD. The genome encodes abundant catabolic functions, including 128 CAZymes, 27 COG and 34 KEGG genes for carbohydrate metabolism, and 54 COG and 45 KEGG genes for amino-acid metabolism, while VFDB and PHI searches indicate low pathogenic potential. Fermentation of wheat bran with Arthrobacter sp . FMD increased carboxylic acids from 21.8–33.4% and decreased fatty acyls from 24.2–10.8%. Isoquercitrin, 2-oxindole-3-acetic acid and 5-hydroxyindole-3-acetic acid were the most up-regulated metabolites, whereas Leu-Trp, 6′-O-feruloyl catalpol and Cnidioside A were the most down-regulated. Isoleucylvaline, γ-glutamyl-methionine and N²-acetylornithine showed the highest increases among amino-acid derivatives, and isovaleric, valeric, 2-hydroxy-2-methylbutyric and 2-hydroxy-3-methylbutyric acids were the predominant organic-acid products. These findings suggest that Arthrobacter sp. FMD deploys a coordinated set of hydrolases and downstream catabolic enzymes that degrade lignocellulose-derived substrates, reduce anti-nutritional factors and enrich organic acids, nucleosides and flavonoids, highlighting its potential to improve feed utilisation and gut health in the forest musk deer.