Abstract

The potential of biofilm formation of 16 Paenibacillus strains and their inhibitory effect against bacterial wilt of tomato seedlings were examined in this study. The crystal violet assay indicated that all strains of Paenibacillus except strain MB02-1202 formed biofilm after 96 and 144 h of incubation while there was not significant difference in biofilm formation between strains of Paenibacillus polymyxa and strains of Paenibacillus macerans. However, the increase level of biofilm formation was associated with the increase of the incubation time and the initial inoculum density. In addition, allPaenibacillus strains except strain MB02-428 reduced wilt incidence in tomato seedlings inoculated with Ralstonia solanacearum while the cell numbers of R. solanacearum inrhizosphere soil was reduced by all Paenibacillus strains compared to the pathogen control. In general, most strains of Paenibacillus were able to both form biofilm and protect tomato seedlings from bacterial wilt, indicating that biofilm formation may play an important role in the biocontrol of Paenibacillus. This is first study regarding the relationship between in vitro biofilm formation ability of Paenibacillus strains and their inhibitory activity against R. solanacearum.

Key words: Biofilm, Paenibacillus, Ralstonia solanacearum, tomato.