In order to optimize synthetic biocatalytic transformations catalyzed by lipases, a large number of enzyme preparations must be tested. Moreover, to design an enzyme for an industrial application it is generally necessary to realize enzyme evolution to improve enzyme performances, for instance thermostability, activity or selectivity. The crucial step is then the screening of the optimal catalyst. Because hydrolytic and synthetic activities are not always correlated, specific screening methods for synthesis activity of lipases are needed. In this work, we report three sensitive and specific screening methods to measure synthetic activity of lipases in vivo on an agar plate and in vitro, directly from culture broth. (c) 2006 Elsevier Inc. All rights reserved.