A Gram-stain-negative, aerobic, rod-shaped, non-motile and orange-coloured marine bacterium, YH207(T), was isolated from a tidal flat at Yeongheung-do on the coast of the Yellow Sea, Korea. 16S rRNA gene sequence analysis revealed that strain YH207(T) was affiliated with the family Cryomorphaceae and showed highest similarity to Brumimicrobium glaciale IC156(T) (95.4 %). Growth was observed at 11-36 °C, at pH 6.5-10.0 and with 0.4-7.0 % NaCl. The predominant cellular fatty acids when grown at 20 °C were iso-C15 : 0 (44.2 %), iso-C15 : 1 G (34.3 %), iso-C17 : 0 3-OH (8.7 %) and summed feature 3 (comprising iso-C15 : 0 2-OH and/or C16 : 1ω7c; 2.3 %). The major respiratory quinone was MK-6. Phosphatidylethanolamine, phosphatidylglycerol, three unidentified lipids, three unidentified aminophospholipids, one unidentified phospholipid, four unidentified aminolipids and three unidentified glycolipids were identified as major polar lipids. The DNA G+C content was 34.3 mol%. On the basis of the data from our polyphasic taxonomic study, strain YH207(T) should be classified in a novel species in the genus Brumimicrobium, for which the name Brumimicrobium mesophilum sp. nov. is proposed. The type strain is YH207(T) ( = KCCM 42331(T) = JCM 14063(T)). Emended descriptions of the genus Brumimicrobium and Brumimicrobium glaciale Bowman et al. 2003 are also given.