Serrawettin W1 produced by Serratia marcescens is a surface-active exolipid resulting in a lot foam formation during the 2,3-butanediol (2,3-BD) fermentation process. In order to avoid excessive addition of antifoam agent and microbial contamination, S. marcescens mutants deficient in serrawettin W1 formation were successfully constructed through insertional inactivation of the swrW gene coding for serrawettin W1 synthase. The shake flask and batch experiments suggested that disruption of the swrW gene led to significant reduction of the foam formation and improved 2,3-BD production a little. Ultimately, fed-batch culturing of the mutant afforded a maximum 2,3-BD concentration of 152 g l(-1) with a productivity of 2.67 g l(-1) h(-1) and a yield of 92.6% at 57 h.