Description of Kinneretia algicola sp. nov. isolated from a freshwater green alga, and reclassification of 9 species within the family Sphaerotilaceae.

A Gram-stain-negative, oxidase-positive, catalase-negative, motile, rod-shaped bacterium, designated strain M5-1T, was isolated from a freshwater green alga. Strain M5-1T was obligately aerobic and contained ubiquinone-8 (Q-8) as the sole respiratory quinone. The major fatty acids (>10%) were C16:0, C12:0, summed feature 3 (C16:1ω7c and/or C16:1ω6c), and summed feature 8 (C18:1ω7c and/or C18:1ω6c), and the major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The genomic DNA G+C content was 67.3 mol%. Based on 16S rRNA gene sequence analysis, strain M5-1T was most closely related to Roseateles cavernae (proposed herein as Kinneretia cavernae) YIM B04394T (99.3%) and Kinneretia oligotropha CHU3T (98.3%). Genome-based phylogenomic analyses consistently placed strain M5-1T together with R. cavernae within the genus Kinneretia. Pairwise average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain M5-1T and R. cavernae were 96.1% and 66.9%, respectively, whereas comparisons with all other type strains yielded ANI and dDDH values of ≤81.1% and ≤23.6%, respectively, supporting its recognition as a novel species. Based on its phylogenomic, genomic, phenotypic, and chemotaxonomic characteristics, strain M5-1T (=KACC 22491T=JCM 34976T=FBCC-B22965T) represents a novel species of the genus Kinneretia, for which the name Kinneretia algicola sp. nov. is proposed. In addition, comprehensive phylogenomic and genome-relatedness analyses support the transfer of six Roseateles and Paucibacter species to Kinneretia, two Roseateles species to Pelomonas, and Aquabacterium humicola to Pseudaquabacterium, providing a revised genome-based taxonomic framework for the family Sphaerotilaceae.