Luteimonas flava sp. nov. and Aquilutibacter rugosus gen. nov., sp. nov., isolated from freshwater environments in China and re-examining the taxonomic status of genera Luteimonas and Lysobacter.

Abstract

Three Gram-stain-negative, aerobic, short rod-shaped and motile strains (FXH3W^T, SHGZ20W and SMYT11W^T) were isolated from freshwater environments in China. Comparisons based on the 16S rRNA gene sequences indicated that strains FXH3W^T and SHGZ20W showed the highest 16S rRNA gene sequence similarity of about 99.6% to 'Luteimonas cellulosilyticus' MIC 1.5, and strain SMYT11W^T showed the highest 16S rRNA gene sequence similarity of 99.8% to Luteimonas fraxinea D4P002^T, respectively. Observing the phylogenetic trees reconstructed based on the 16S rRNA gene sequences, the species of genera Luteimonas and Lysobacter were not monophyletic and often mixed together. The further reconstructed phylogenomic tree and Genome Taxonomy Database also showed that the species of both genera were polyphyletic, implying that the current taxonomic status of the species of both genera was questionable. The calculated OrthoANIu, digital DNA-DNA hybridization and average amino acid sequence identity (AAI) values supported that strains FXH3W^T and SHGZ20W should belong to the same novel species and strain SMYT11W^T should also represent an independent novel species. Combining the AAI values and phylogenomic analyses, the species of genera Luteimonas and Lysobacter should be reassigned to 12 genera (Luteimonas, Lysobacter, Cognatiluteimonas, Noviluteimonas, Pseudoluteimonas, Solilutibacter, Agrilutibacter, Cognatilysobacter, Marilutibacter, Novilysobacter, Montanilutibacter and Aerolutibacter). The AAI values 69.5-76.0% were also proposed as the Lysobacteraceae-specific thresholds for genus delineation. Strain SMYT11W^T should represent a novel species of the genus Luteimonas, for which the name Luteimonas flava sp. nov. (type strains SMYT11W^T=GDMCC 1.4275^T=KCTC 8304^T) is proposed. Strains FXH3W^T and SHGZ20W should represent a novel species of a new genus Aquilutibacter rugosus gen. nov., sp. nov. The type strain of the type species is FXH3W^T (=GDMCC 1.4096^T=KCTC 8154^T).