Considering that the surface properties of demulsifying cells correlate with their demulsification efficiency, the demulsifying bacteria Alcaligenes sp. S-XJ-1 with various surface properties were obtained using different vegetable oils as carbon sources. The results show that better performance was achieved with demulsifying bacteria S-XJ-1 possessing a relatively high cell surface hydrophobicity (CSH) and total unsaturated degree for the cell-wall bound fatty acids. There also appeared to be a correlation between the specific cell-wall bound fatty acid components of the bacteria, in terms of carbon chain length or degree of unsaturation, and either CSH or demulsification efficiency. The fatty acids attached to the cell wall were mainly composed of palmitic acid (C16:0), stearic acid (08:0), oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). C18:1 and C18:2 had a positive effect on the formation of CSH, while C18:0 and C18:3 had the opposite effect. (C) 2011 Elsevier Ltd. All rights reserved.