X-gal inhibits the swarming of Vibrio species.

Abstract The expressional levels of genes in swarmer cells can be determined by a simple method using X-gal-containing semisolid agars and lacZ -fusion transcription reporter strains of the genes concerned. However, X-gal alone inhibited the swarming of Vibrio , regardless of their ability to digest X-gal. Moreover, X-gal inhibited the growth of V. vulnificus containing functional lacZ . These effects of X-gal itself should be carefully considered when trying to determine the expression levels of genes in swarming cells using X-gal-containing semisolid agar.