A taxonomic study was carried out on strain CY1(T), which is a novel bacterium isolated from wastewater sludge of a melamine-producing factory in Sanming city, Fujian, China. Strain CY1(T) was shown to rapidly and completely degrade melamine to NH3 and CO2 under aerobic conditions. The isolate was Gram-stain-negative, short-rod-shaped and motile by one unipolar flagellum. Growth was observed at salinities from 0 to 7% NaCl (optimum, 0.1%), at temperatures from 15 to 50 °C (optimum, 40-45 °C) and at pH 7-9.5 (optimum pH 9.5). Quinone-8 was detected as the major respiratory quinone. 16S rRNA gene sequence comparisons showed that strain CY1(T) was affiliated to the family Comamonadaceae in the class Betaproteobacteria. It was most closely related to members of the genera Alicycliphilus (95.5%), Diaphorobacter (94.6-95.1%), Acidovorax (92.9-95.4%), Delftia (93.0-93.6%) and Comamonas (92.6-93.9%). The average nucleotide identity (ANI) values between strain CY1(T) and those representing related genera ranged from 84.0 to 86.1% using Mummer, and from 74.9 to 81.1% using BLAST. The dominant fatty acids were C(16 : 1)ω7c and/or C(16 : 1)ω6c, C(16 : 0), C(10 : 0) 3-OH and C(18 : 1)ω7c and/or C(18 : 1)ω6c, and the major polar lipids consisted of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, one unidentified phospholipid and one unidentified aminophospholipid. The G+C content of the chromosomal DNA was 69.5 mol%. On the basis of the phenotypic and phylogenetic data, strain CY1(T) represents a novel species of a new genus, for which the name Melaminivora alkalimesophila gen. nov., sp. nov. is proposed. The type strain of Melaminivora alkalimesophila is CY1(T) ( = CCTCC AB 2012024(T) = DSM 26006(T)).
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