Abstract
Mining novel Streptomyces species from extreme environments provides a valuable strategy for the discovery of new antibiotics. Here, we report a strain of Streptomyces sp. HMX87(T), which exhibits antimicrobial activity and was isolated from desert soil collected in the Tuha Basin, China. Molecular taxonomic analysis revealed that the 16S rRNA gene sequence of strain HMX87(T) shares the highest similarity with those of Streptomyces bellus CGMCC 4.1376(T) (98.5%) and Streptomyces coerulescens DSM 40146(T) (98.43%). In phylogenetic trees, it formed a distinct branch. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain HMX87(T) and the above two type strains were below the thresholds of 95% and 70%, respectively, confirming that strain HMX87(T) represents a novel species within the genus Streptomyces, for which the name Streptomyces hamibioticus sp. nov. is proposed. Physiologically, the strain HMX87(T) grew at temperatures ranging from 25 to 37 °C, tolerated pH values from 5 to 12, and survived in NaCl concentrations of 0% to 8% (w/v). Chemotaxonomic characterization indicated the presence of LL-diaminopimelic acid (LL-DAP) in the cell wall, ribose and galactose as whole-cell hydrolysate sugars, MK-9(H8) (66.3%) as the predominant menaquinone, and iso-C(16:0) (25.94%) and anteiso-C(15:0) (16.98%) as the major fatty acids characteristics that clearly distinguish it from its closest relatives. Whole-genome sequencing of strain HMX87(T) revealed an abundance of genes associated with high-temperature tolerance, salt-alkali resistance, and antimicrobial activity. The genomic features and secondary metabolic potential reflect its adaptation to extreme environmental conditions, including high temperature, salinity, alkalinity, strong ultraviolet radiation, and oligotrophic nutrients. The strain HMX87(T) has been deposited in the Czech Collection of Microorganisms (CCM 9454(T)) and the Guangdong Microbial Culture Collection Center (GDMCC 4.391(T)). The 16S rRNA gene and whole-genome sequences have been submitted to GenBank under accession numbers PQ182592 and PRJNA1206124, respectively.