PATHOGEN IDENTIFICATION AND DETECTION The bacterium Xanthomonas campestris pv. campestris (Pammel) Dowson is a Gram
negative rod, that occur mostly alone or in pairs and is usually motile by means of a
single polar flagellum (Figure 1d). Most strains form yellow, mucoid, glistening
colonies (Figures 1e and 1f). The yellow pigments, xanthomonadins (mono- or
dibromo arylpolyene structures), and the exopolysaccharide xanthan, responsible for
the mucoid or viscous cultures, are typical of the genus (Vauterin et al., 1995),
although the existence of atypical pigmented isolates has been reported (Poplawsky
and Chun, 1995).