Sphingomonas dokdonensis sp. nov., isolated from soil

Area of Science:

• Microbiology
• Bacterial Taxonomy
• Environmental Science

Background:

• Sphingomonas species are ubiquitous in various environments.
• Accurate bacterial classification is crucial for understanding microbial ecology and function.
• Soil microbial communities harbor diverse and often uncharacterized bacterial populations.

Purpose of the Study:

• To taxonomically characterize a novel Sphingomonas-like bacterial strain, DS-4(T), isolated from Dokdo soil.
• To determine if strain DS-4(T) represents a new species within the genus Sphingomonas.
• To provide a comprehensive polyphasic description of the novel species.

Main Methods:

• Polyphasic taxonomic approach including phenotypic, phylogenetic, and genetic analyses.
• Cultivation on trypticase soy agar, determination of optimal growth conditions (pH, temperature, salinity).
• Analysis of major fatty acids, polar lipids, ubiquinone system, DNA G+C content, 16S rRNA gene sequencing, and DNA-DNA hybridization.

Main Results:

• Strain DS-4(T) is a Gram-negative, rod-shaped bacterium with optimal growth at pH 6.0-6.5 and 25°C without NaCl.
• Major fatty acids include C(18:1)ω7c, C(16:0), C(14:0) 2-OH, and C(16:1)ω7c/iso-C(15:0) 2-OH; predominant ubiquinone is Q-10.
• Phylogenetic analysis based on 16S rRNA gene sequences showed 93.0-97.6% similarity to known Sphingomonas species; DNA-DNA relatedness confirmed its distinctiveness, supporting its classification as a new species, Sphingomonas dokdonensis sp. nov.

Conclusions:

• Strain DS-4(T) represents a novel species of the genus Sphingomonas, named Sphingomonas dokdonensis sp. nov.
• The polyphasic approach confirmed its unique phylogenetic and genetic position.
• This discovery expands the known diversity within the Sphingomonas genus and highlights the microbial richness of Korean soil ecosystems.