Characterization of a Novel Species Isolated from the Kumtagh Desert and Genomic Insights into the Secondary Metabolite Potential of the Genus.

A novel actinobacterial strain, designated E54, was isolated from a hyper-arid desert soil sample collected from the Kumtagh Desert in Dunhuang, Gansu Province, China. Phylogenetic analysis based on 16S rRNA gene sequences placed strain E54 within the genus , showing highest similarity to DSM 44232 (98.9%) and NBRC 15743 (98.5%). However, whole-genome comparisons revealed that the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between E54 and these related strains were below the thresholds for species delineation. Strain E54 exhibited typical morphological characteristics of the genus , forming a branched substrate. It grew optimally at 28-30 °C, pH 7.0-9.0, and tolerated up to 10% NaCl. The cell wall contained meso-diaminopimelic acid, the predominant menaquinone was MK-9(H), and major fatty acids included iso-C. The polar lipid profile comprised diphosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl inositol, hydroxyphosphatidyl ethanolamine, and an unidentified lipid. The characteristic amino acid type of the cell wall was meso-DAP. Whole-cell hydrolysis experiments revealed the characteristic cell wall sugar fractions: ribose and galactose. The genome of strain E54 is approximately 8.0 Mb with a DNA G+C content of 69.38 mol%. Genome mining revealed 39 biosynthetic gene clusters (BGCs), including non-ribosomal peptide synthetases (NRPS), polyketide synthases (PKS), terpenes, and siderophores. Comparative antiSMASH-based genome analysis across 38 strains further demonstrated the genus' remarkable biosynthetic diversity. NRPS and type I PKS (T1PKS) were the most prevalent BGC types, indicating a capacity to synthesize structurally complex and pharmacologically relevant metabolites. Together, these findings underscore the untapped biosynthetic potential of the genus and support the proposal of strain E54 as a novel species. The strain E54 (=JCM 34936 = GDMCC 4.216) should represent a novel species, for which the name sp. nov. is proposed.