Ramlibacter humi sp. nov., isolated from tropical forest soil

Area of Science:

• Microbiology
• Bacteriology
• Taxonomy

Background:

• The genus Ramlibacter comprises Gram-negative bacteria with limited species described.
• Soil environments are rich reservoirs of microbial diversity, including potentially novel bacterial taxa.

Purpose of the Study:

• To isolate and characterize a novel bacterial strain from a forest soil sample.
• To determine the phylogenetic and chemotaxonomic properties of the isolate.
• To formally propose a new species within the genus Ramlibacter.

Main Methods:

• Isolation of strain 18x22-1^T from forest soil.
• 16S rRNA gene sequence analysis for phylogenetic placement.
• Chemotaxonomic analyses including respiratory quinones, fatty acids, and polar lipids.
• Genome sequencing to determine genome size and G+C content.
• Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) calculations.

Main Results:

• Strain 18x22-1^T is a Gram-stain-negative, aerobic, non-motile bacterium.
• Phylogenetic analysis showed highest similarity (98.5%) to Ramlibacter tataouinensis.
• Chemotaxonomic data revealed ubiquinone-8 as the major respiratory quinone and specific major fatty acids.
• Genome size was 4.47 Mb with a G+C content of 68.9 mol%.
• ANI and dDDH values were below thresholds for species delineation with related Ramlibacter strains.

Conclusions:

• Strain 18x22-1^T represents a novel species of the genus Ramlibacter.
• The proposed name for the novel species is Ramlibacter humi sp. nov.
• The type strain is 18x22-1^T (=GDMCC 1.1584^T=KCTC 52922^T).