Nocardioides silvaticus sp. nov., isolated from forest soil

Area of Science:

• Microbiology
• Bacteriology
• Taxonomy

Background:

• The genus Nocardioides comprises Gram-positive, aerobic actinobacteria found in diverse environments.
• Accurate taxonomic classification is crucial for understanding microbial diversity and ecological roles.

Purpose of the Study:

• To characterize a novel bacterial isolate, strain S-34^T, from forest soil.
• To determine the taxonomic affiliation of strain S-34^T within the genus Nocardioides.
• To propose a new species designation based on comprehensive polyphasic analysis.

Main Methods:

• Isolation and cultivation of bacterial strain S-34^T from forest soil.
• 16S rRNA gene sequence analysis for phylogenetic placement.
• DNA-DNA hybridization and genome-based phylogenetic analysis (orthoANI).
• Analysis of chemotaxonomic properties: cell wall peptidoglycan, polar lipids, respiratory quinones, and fatty acids.
• Determination of DNA G+C content and genome size.

Main Results:

• Strain S-34^T showed highest 16S rRNA gene sequence similarity (97.3%) to Nocardioides thalensis NCCP-696^T.
• DNA-DNA relatedness values were below the species delineation threshold (50.6% with N. thalensis CCTCC AB 2016296^T).
• Genome-based analysis (orthoANI 82.4% with N. immobilis CCTCC AB 2017083^T) and chemotaxonomic data supported its distinctiveness.
• The G+C content of the genome was 71.2 mol%.

Conclusions:

• Strain S-34^T represents a distinct lineage within the Nocardioides genus, differentiated by phylogenetic, genomic, and chemotaxonomic data.
• The proposed name Nocardioides silvaticus sp. nov. is introduced for this novel species.
• The type strain is S-34^T (=KCTC 49137^T=CCTCC AB 2018079^T).