Microvirga terrae sp. nov., Isolated from Soil

Area of Science:

• Microbiology
• Bacterial Taxonomy
• Genomics

Background:

• The genus Microvirga comprises plant-associated bacteria, and understanding its diversity is crucial for agricultural and environmental science.
• New bacterial species discovery contributes to a comprehensive understanding of microbial ecosystems and their functions.

Purpose of the Study:

• To isolate and characterize a novel bacterial strain from soil.
• To determine the taxonomic placement of the novel strain using polyphasic characterization, including genomic and phylogenetic analyses.

Main Methods:

• Isolation and cultivation of strain R24 from soil.
• Phenotypic characterization including Gram staining, motility, and growth conditions (temperature, pH, salinity).
• Chemotaxonomic analysis of respiratory quinones, fatty acids, and polar lipids.
• Genomic analysis including DNA G+C content determination and 16S rRNA gene sequencing.
• Phylogenetic analysis and calculation of Average Nucleotide Identity (ANI) and digital DNA-DNA hybridization (dDDH) values.

Main Results:

• Strain R24 was identified as a Gram-negative, strictly aerobic, non-motile rod.
• Optimal growth occurred at 25–30 °C, pH 8.0–9.0, and without added NaCl.
• Chemotaxonomic analysis revealed ubiquinone-10, major fatty acids C16:0, C18:0, and summed feature 8, with specific polar lipids.
• Genomic analysis showed a DNA G+C content of 64.4%.
• Phylogenetic analysis placed strain R24 within the genus Microvirga, closely related to Microvirga aerilata.
• ANI and dDDH values were below the thresholds for species delineation with existing Microvirga species.

Conclusions:

• Strain R24 represents a novel species within the genus Microvirga.
• The proposed name for this new species is Microvirga terrae sp. nov.
• The type strain is R24 (KACC 21784^T = JCM 34259^T).