Comprehensive mechanistic insights into the in vitro antibiofilm activity of graphene oxide (GO) nanopesticides against phytopathogen Ralstonia solanacearum.

Biofilms constitute the primary virulence factor in Ralstonia solanacearum (R. solanacearum), a soilborne bacterial plant pathogen, providing protection against antimicrobials and host defenses. Investigating biofilm inhibitors is both necessary and scientifically valuable. This study systematically evaluated the antibiofilm activities of graphene oxide (GO) and elucidated the underlying molecular mechanisms. The findings demonstrated that GO substantially diminished the formation of mature biofilms. Additionally, GO underwent bio-reduction within the culture system, as confirmed by various characterization techniques, which is closely related to its high antibiofilm activity. Monitoring revealed significantly reduced bacterial motility (swimming, swarming, and twitching), decreased protein and exopolysaccharide (EPS) content, and elevated reactive oxygen species (ROS) activity in biofilm cells exposed to GO. Furthermore, GO disrupted two- and three-dimensional biofilm architectures through the formation of GO-bacteria aggregates via direct interaction with bacterial cells, leading to compromised cell membranes and cytoplasmic vacuolization. Transcriptomic profiling indicated that numerous genes in R. solanacearum were significantly regulated after 24 h of exposure to 250 mg/L GO, affecting critical biological pathways associated with biofilms, such as chemotaxis, quorum sensing, flagellar synthesis, flagellar assembly, biofilm formation, cell membrane integrity, and amino acid metabolism. These results offer conceptual insights into the potential application of GO as an efficient nanopesticide for controlling plant diseases and suggest a promising strategy for combating biofilm-related bacterial infections.