Biofilm formation by phytopathogenic bacteria Acidovorax citrulli subsp. citrulli and Ralstonia solanacearum

Phytopathogenic bacteria are responsible for causing several losses in agriculture economic world. Biofilm formation presents itself as an important structure related to bacterial virulence. The objective of this study was to investigate the biofilm formation by Ralstonia solanacearum and Acidovorax citrulli isolates. Quantification of biofilm formation was performed by the crystal violet method, using NYD as the standard medium for both bacteria, TZC as a specific medium for R. solanacearum and YDC for A. citrulli . The biofilm was observed in SEM and CLSM. Under the tested conditions, B5-5, CGH8, CGM10 and CGH26 R. solanacearum isolates and Aac1.43 and Aac1.73 A. citrulli isolate formed moderately or strongly biofilm on both media tested. However, the amount of biofilm produced by R. solanacearum was higher than those produced by A. citrulli . The SEM and CLSM revealed structurally distinct biofilms among isolates of R. solanacearum , which did not occur for A. citrulli isolates. We conclude that R. solanacearum is a strong biofilm producer, while A. citrulli not seem to be well suited to this condition by not adhere well to the surface. This species depicts potentials to become natural models to study plant biofilm infections due to the high number of host species.