A novel gram-negative, non-spore-forming, mobile, estrogen-degrading strain, MH-B5(T), was isolated from Yundang Lagoon in Xiamen city of China. Growth of this strain occurred between 4 and 40 A degrees C (optimum at 35 A degrees C), pH 5.5-10.0 (7.5), 0.0-7 % NaCl (1-2 %). Phylogenetic analysis based on 16S rRNA gene sequence showed that strain MH-B5(T) belonged to the genus Altererythrobacter family Erythrobacteraceae, showing the highest sequence similarity (96.6 %) to Altererythrobacter xinjiangensis S3-63(T). The dominant cellular fatty acid was C-18:1 omega 7c and/or C-18:1 omega 6c (57.98 %). The major respiratory quinone was ubiquinone 10, and major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid, phospholipid, and phosphatidylcholine. Strain MH-B5(T) did not contain bacteriochlorophyll a. The draft genome sequence of strain MH-B5(T) comprised about 3.67 Mb, with an average G+C content of 60 mol%. On the basis of data from its morphology, chemotaxonomy, 16S rRNA gene sequence and genome sequence, strain MH-B5(T) represents a novel species, for which the name Altererythrobacter estronivorus sp. nov., is proposed. The type strain is MH-B5(T) (=CCTCC AB2012025(T)=DSM 25986(T)).