Description and Genomic Characteristics of Diaphorobacter limosus sp. nov., Isolated from a Sewage-Treatment Plant

A Gram-stain-negative, rod-shaped, non-motile, catalase-positive, denitrifying bacterium, designated strain Y-1T, was isolated from an aeration tank of a sewage treatment plant in China and characterized using polyphasic taxonomic approaches. Strain Y-1T could grow at 10-37 °C (optimum 25 °C), at pH 5.0-10.0 (optimum 7.0) and in the presence of 0-3.0% (w/v) NaCl (optimum 0.5%). The phylogenetic tree based on the 16S rRNA gene sequences revealed that strain Y-1T was a member of genus Diaphorobacter, and showed the highest sequence similarities with Diaphorobacter oryzae RF3T (97.50%), Diaphorobacter nitroreducens NA10BT (97.38%) and Diaphorobacter aerolatus 8604S-37T (96.56%). In terms of carbon source utilization and enzyme activities, strain Y-1T was significantly different from its similar strains. The major respiratory quinone was Q-8, and the main polar lipid was phosphatidylethanolamine. Comparative genomic analysis of strain Y-1T and other Diaphorobacter species was conducted to explore the mechanisms underlying the differences among these strains. Strain Y-1T encoded 3957 genes, consisting of 3813 protein-coding genes and 144 RNA coding genes, and encoded 652 enzymes with 31 unique enzymes compared with other related species. The DNA G + C content was 69.95 mol%. Strain Y-1T exhibited 41.71% DNA-DNA relatedness and 95% ANIb with the most related type strains.On the basis of the evidence presented from polyphasic analysis, strain Y-1T was suggested as a novel species within the genus Diaphorobacter, for which the name Diaphorobacter limosus sp. nov. is proposed, with the type strain Y-1T (= KCTC 92852T = CCTCC AB 2023032T).

Melaminivora suipulveris sp. nov., isolated from pigpen dust

A bacterial strain designated SC2-9^T was isolated from the dust collector of a pigpen located in Wanju-gun, Jeollabuk-do, Republic of Korea. Cells were strictly aerobic, Gram-stain-negative, flagellated and rod-shaped. The strain was catalase- and oxidase-positive, and grew optimally 28-30 °C, pH 8.0 and 0 % NaCl (w/v). Phylogenetic analysis based on 16S rRNA gene sequences showed 99.1 and 98.3 % similarities to Melaminivora jejuensis KBB12^T and Melaminivora alkalimesophila CY1^T, and revealing less than 97 % similarity to other validly named species. The genomic DNA G+C content of strain SC2-9^T was 68.2 %. The orthologous average nucleotide identity and dDDH values of strain SC2-9^T with the closest species Melaminivora jejuensis KCTC 32230^T were 85.6 and 29.3 %, respectively. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, three unidentified aminolipids and one unidentified lipid. The major fatty acids (>10 %) were summed feature 3 (C_16 : 1  ω6c and/or C_16 : 1  ω7c), C_16 : 0 and summed feature 8 (C_18 : 1  ω6c and/ or C_18 : 1  ω7c). The predominant isoprenoid quinone was ubiquinone-8. Based on phenotypic, chemotaxonomic and phylogenetic data, strain SC2-9^T should be assigned as a novel species of the genus Melaminivora, for which the name Melaminivora suipulveris sp. nov. is proposed. The type strain is SC2-9^T (=KACC 19310^T=NBRC 113103^T).