GpsX is involved in polysaccharide biosynthesis in X. citri subsp. citri. (A) EPS production in NB medium supplemented with 2% (w/v) glucose by wild type strain 306 and its derivatives. The data presented are the means ± SD of triplicate measurements from a representative experiment; similar results were obtained in two other independent experiments. (B) Analysis of LPS synthesis. The LPSs produced by wild type strain 306 and its derivatives were extracted, subjected to SDS-PAGE analysis, and visualized by silver staining. The lost bands in the mutants are indicated by arrows. WT: wild-type strain 306; M: gpsX mutant C223 G4 (gpsX-); MV: gpsX mutant 223G4V (gpsX-) with empty vector pUFR053; CM: complemented gpsX mutant C223 G4 (gpsX+); S: LPS standard from S. enterica serovar Typhimurium (10 μg; Sigma). The experiments were repeated three times with similar results, and the results of only one experiment are presented.