A novel, gelatinous, colony-forming, rod-shaped bacterial strain, designated IK01 was isolated from biofilms formed on the membrane surface of a sewage-treating membrane bioreactor (MBR). Strain IK01 produced gelatinous and almost transparent colonies at lower medium concentrations. Fourier transform infrared analysis of the gelatinous colony matrix showed that the matrix could be a biofilm substance. This suggests that strain IK01 is a fouling-causing bacteria in the MBR. Furthermore, 16S rRNA gene sequence analysis showed that strain IK01 was phylogenetically placed in the genus The average nucleotide identity values for IK01 and the other 50 species of the genus ranged from 78.5 to 83.9 %. Correspondingly, the estimated digital DNA-DNA hybridization values ranged from 20.8 to 24.4 %. The genomic DNA G + C content was 66.0 %. The predominant fatty acids were summed feature 8 (C 7 and/or C 6), summed feature 3 (C 7 and/or C 6), and C 2-OH. A polar lipid profile revealed phosphatidylethanolamine, two unidentified phospholipids, and three aminoglycophospholipids as major compounds. The major respiratory quinone was ubiquinone Q-10. Genotypic, chemotaxonomic, and phenotypic analyses characterized the newly identified strain IK01, as a novel species of the genus for which we propose the name sp. nov. The type strain is IK01 (NBRC 116408 = DSM 116658).