Foliimonas ilicis gen. nov., sp. nov., a carbon monoxide-oxidizing bacterium belonging to a novel genus of the family Phyllobacteriaceae isolated from leaves of Ilex aquifolium

A novel carbon monoxide (CO)-oxidizing bacterial strain designated as SB112^T was enriched and isolated from <i>Ilex aquifolium</i> leaves from Tocil Wood Nature Reserve in Coventry, UK. The strain was Gram reaction-negative, aerobic, rod-shaped, motile with a polar flagellum and non-spore-forming. Growth of strain SB112^T was observed at 10-45 °C, pH 6.0-12.0 and NaCl concentrations of 1-3%. The genomic DNA G+C content was 58.3 mol%, and the major fatty acids (>10%) of strain SB112^T were C_{18 : 1} ω7c, C_{18 : 1} ω7c 11-methyl and C_{19 : 0} cyclo ω7c. Major polar lipids were phosphatidylcholine, diphosphatidylglycerol, phosphatidylglycerol and a phospholipid. Strain SB112ᵀ contains ubiquinone-10 as the major respiratory quinone. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SB112^T formed a separate lineage within the family <i>Phyllobacteriaceae</i>, showing sequence identities of 97.7%, 97.6% and 97.5%, with its closest relatives <i>Aminobacter niigataensis</i>, <i>Aminobacter aminovorans</i> and <i>Mesorhizobium plurifarium</i>, respectively. Phylogenomic analyses using whole-genome sequences consistently placed this strain within the family <i>Phyllobacteriaceae</i>. However, its phylogenetic position did not correspond to any known genus within this family. The genome of strain SB112^T was found to possess the form II <i>coxL</i> gene, which encodes the large subunit of the CO dehydrogenase and potentially enables CO oxidation. The average nucleotide identity and digital DNA-DNA hybridization with members of closely related genera yielded values below the thresholds for prokaryotic species delineation (95-96 and 70%, respectively). Based on the phenotypic, chemotaxonomic, phylogenetic, genomic and physiological properties, strain SB112^T is considered to represent a novel species of a new genus <i>Foliimonas</i> within the family <i>Phyllobacteriaceae</i> for which the name <i>Foliimonas ilicis</i> gen. nov., sp. nov. is proposed. The type of strain is SB112^T (=LMG 33802^T, =NCAIM B.02691^T).