2(5H)-Furanone Disrupts Bacterial Biofilm Formation and Indirectly Reduces the Settlement of Plantigrades of the Mussel Mytilus coruscus

Bacterial quorum sensing (QS) is a chemical communication that allows bacteria to coordinate their population and gene regulation in response to threshold concentrations of QS signals. Here, we study the effect of QS inhibitor 2(5H)-furanone (FUR) on the formation of Pseudoalteromonas marina ECSMB14103 biofilms and the effect of these biofilms on the settlement of plantigrades of the mussel Mytilus coruscus. FUR was added during biofilm formation of P. marina ECSMB14103 or in the settlement bioassay. FUR at 10^–4 M added during biofilm formation significantly (p < 0.05) reduced the settlement of plantigrades, and it was associated with a significant (p < 0.05) reduction of bacterial density. The visualization of individual substances in biofilms shows that β-polysaccharides are the major components in the biofilm matrix. The decreased settlement rate may be attributed to the reduction of the biovolume of α-polysaccharides and β-polysaccharides in biofilms. The transcriptome of biofilms treated with 10^–4 M FUR shows 61 genes are differentially expressed. Aspartate kinase and the flagellar assembly protein fliH gene are significantly affected after exposure to 10^–4 M FUR (p < 0.05). They are involved in the synthesis of the bacterial cell wall and the mobility of bacteria, respectively. Exposure to 10^–4 M FUR also significantly changes the carbapenem biosynthesis pathway, which is regulated by the QS system in bacteria (p < 0.05). These data suggest that FUR directly affects biofilm formation by altering extracellular polymeric substances (EPS) components and metabolic processes, which, in turn, indirectly reduce the settlement of plantigrades. The present study provides new insights into the molecular mechanisms of controlling biofouling.