Unique gel-like colony forming bacterium Novosphingobium pituita sp. nov., isolated from a membrane bioreactor (MBR) treating sewage

Abstract

A novel, gelatinous, colony-forming, rod-shaped bacterial strain, designated IK01T was isolated from biofilms formed on the membrane surface of a sewage-treating membrane bioreactor (MBR). Strain IK01T 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 IK01T is a fouling-causing bacteria in the MBR. Furthermore, 16S rRNA gene sequence analysis showed that strain IK01T was phylogenetically placed in the genus Novosphingobium. The average nucleotide identity values for IK01T and the other 50 species of the genus Novosphingobium 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 (C18:1 ω7c and/or C18:1 ω6c), summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), and C14:0 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 IK01T, as a novel species of the genus Novosphingobium, for which we propose the name Novosphingobium pituita sp. nov. The type strain is IK01T (NBRC 116408T = DSM 116658T).

Keywords

• Biofilm
• Gelatinous colony
• Extracellular polymeric substances
• Extracellular polysaccharide