Nocardioides mesophilus sp. nov., isolated from soil

Area of Science:

• Microbiology
• Actinobacteria Taxonomy
• Phylogenetics

Background:

• Actinobacteria are a diverse group of bacteria with significant ecological and industrial roles.
• The genus Nocardioides comprises Gram-positive, aerobic actinobacteria found in various environments.
• Accurate taxonomic classification is crucial for understanding microbial diversity and function.

Purpose of the Study:

• To taxonomically characterize a novel actinobacterial strain, MSL-22(T), isolated from Korean soil.
• To determine the phylogenetic position of strain MSL-22(T) within the genus Nocardioides.
• To propose a new species designation based on polyphasic evidence.

Main Methods:

• Isolation and cultivation of actinobacteria from soil samples.
• Polyphasic taxonomic analysis including 16S rRNA gene sequencing.
• Phylogenetic tree construction and DNA-DNA hybridization.
• Analysis of chemotaxonomic markers (cell-wall peptidoglycan, menaquinone, fatty acids) and DNA G+C content.

Main Results:

• Strain MSL-22(T) is a motile, mesophilic actinobacterium, coccoid- to rod-shaped.
• Phylogenetic analysis based on 16S rRNA gene sequences placed strain MSL-22(T) within the genus Nocardioides, closely related to Nocardioides jensenii (97.3% similarity).
• DNA-DNA relatedness values confirmed strain MSL-22(T) as distinct from its closest relatives.
• Chemotaxonomic data (LL-diaminopimelic acid, MK-8(H₄), specific fatty acid profile) and a DNA G+C content of 68.7 mol% supported its unique identity.

Conclusions:

• Strain MSL-22(T) represents a novel species within the genus Nocardioides.
• The proposed name for this new species is Nocardioides mesophilus sp. nov.
• The type strain is MSL-22(T) (=DSM 19432(T)=KCTC 19310(T)).