Novosphingobium aeonii sp. nov., isolated from leaves of Aeonium decorum, is able to grow with polycyclic aromatic hydrocarbons

Atmospheric pollution poses a major threat to human health, causing millions of deaths worldwide each year. Green infrastructures may help mitigate the toxicity of airborne contaminants through the combined action of plants and their associated microbiota. Two bacterial isolates, I1 ^T and FS9, representing a novel species of the genus Novosphingobium , were obtained from the leaves of Aeonium decorum , a succulent plant native to the Canary Islands (Spain), based on their ability to grow using phenanthrene as the sole carbon source. The genomes of both isolates were sequenced using a hybrid approach combining short- and long-read technologies, resulting in four complete, circularized replicons per genome. A genus-wide comparative analysis including 400 quality-checked Novosphingobium genomes, among them 74 assemblies corresponding to type strains and the 2 novel isolates , revealed that the closest validly published species was represented by the type strain genome of Novosphingobium lindaniclasticum LE124 ^T (DSM 10700 ^T =NBRC 16058 ^T ), which showed the highest ANI values with isolates I1 ^T and FS9, 86.60% and 86.58%, respectively, and dDDH values of 26.4%, supporting their assignment to a novel species. This analysis also identified four additional strains, previously deposited in public databases as Novosphingobium sp . , which fall within the ANI and genomic distance thresholds (≥95%) of the proposed species. Phylogenetic analysis based on 16S rRNA gene sequences and chemotaxonomic characterization further corroborated this taxonomic placement. We propose the name Novosphingobium aeonii sp. nov. for this novel species. The proposed type strain, N. aeonii I1 ^T (CET 31212 ^T =DSM 119885 ^T ), has a genome size of 5.76 Mbp and a DNA G+C content of 64.76%.