Cellulomonas citrea sp. nov., isolated from paddy soil

Two Gram-stain-positive, facultatively anaerobic, motile, aerobic, rod-shaped and non-spore-forming actinobacteria, strains AO-9^T and AO-18, were isolated from paddy soil collected from Daejeon, Republic of Korea. Colonies were smooth, lemon-yellow and circular and 0.5-0.8×2.0-2.4 µm in diameter after 3 days of incubation at 28 °C on tryptic soy agar. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strains AO-9^T and AO-18 belonged to the genus Cellulomonas, showing the highest sequence similarities to Cellulomonas marina FXJ8.089^T (96.6 %), Cellulomonas endophytica SYSUP0004^T (96.5 %), Cellulomonas gelida DSM 20111^T (96.2 %), Cellulomonas uda DSM 20107^T (96.1 %), Cellulomonas rhizosphaerae NEAU-TCZ24^T (96.1 %), Cellulomonas composti TR7-06^T (96.0 %), Cellulomonas persica JCM 18111^T (96.0 %) and less than 96 % to other closely related species. The DNA-DNA hybridization values between strains AO-9^T and AO-18 were 87 %. The average nucleotide identity and digital DNA-DNA hybridization values between strain AO-9^T and type strains of related species of the genus Cellulomonas were 84.0-85.8 % and 20.3-20.9 %, respectively. The major cellular fatty acids are anteiso-C_15:0 (49.9 %), C_14:0 (12.9 %) and iso-C_14:0 (12.1 %). The predominant isoprenoid quinone was MK-9 (H₄). The polar lipid profile consists of diphosphatidylglycerol, phosphatidylglycerol and one unidentified lipid. The DNA G+C content was 72.9 mol%. Based on its distinctive phenotypic, phylogenetic and chemotaxonomic characteristics, the two strains are considered to represent novel species of the genus Cellulomonas, for which the name Cellulomonas citrea sp. nov. is proposed. The type strain is AO-9^T (=KACC 19069^T=NBRC 112523^T).