Universidad de Barcelona 1 article published in JoVE Immunology and Infection Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility Juan M. Tomás1, Kelly M. Fulton2,3, Susan M. Twine2,4, Susana Merino1 1Departamento de Genética, Microbiología y Estadística, Universidad de Barcelona, 2Human Health Therapeutics Research Centre, National Research Council Canada, 3Department of Chemistry, Carleton University, 4Department of Biology, Carleton University Here, we describe the construction of null mutants of Aeromonas in specific glycosyltransferases or regions containing glycosyltransferases, the motility assays, and flagella purification performed to establish the involvement and function of their encoded enzymes in the biosynthesis of a glycan, as well as the role of this glycan in bacterial pathogenesis.