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-1 T , was isolated from an aeration tank of a sewage treatment plant in China and characterized using polyphasic taxonomic approaches. Strain Y-1 T 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-1 T was a member of genus Diaphorobacter, and showed the highest sequence similarities with Diaphorobacter oryzae RF3 T (97.50%), Diaphorobacter nitroreducens NA10B T (97.38%) and Diaphorobacter aerolatus 8604S-37 T (96.56%). In terms of carbon source utilization and enzyme activities, strain Y-1 T 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-1 T and other Diaphorobacter species was conducted to explore the mechanisms underlying the differences among these strains. Strain Y-1 T 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-1 T 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-1 T 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-1 T (= KCTC 92852 T  = CCTCC AB 2023032 T ).