Inhibiting bacterial biofilm formation by stimulating c-di-GMP regulation using citrus peel extract from Jeju Island

Biofilms consist of single or multiple species of bacteria embedded in extracellular polymeric substances (EPSs), which affect the increase in antibiotic resistance by restricting the transport of antibiotics to the bacterial cells. An alternative approach to treatment with antimicrobial agents is using biofilm inhibitors that regulate biofilm development without inhibiting bacterial growth. In this study, we found that citrus peel extract from Jeju Island (CPEJ) can inhibit bacterial biofilm formation. According to the results, CPEJ concentration-dependently reduces biofilm formation without affect-ing bacterial growth. Additionally, CPEJ decreased the production of extracellular polymeric substances but increased bacterial swarming motility. These results led to the hypothesis that CPEJ can reduce intracellular bis-(3 '-5 ')-cyclic di-meric guanosine monophosphate (c-di-GMP) concentration. The results showed that CPEJ significantly reduced the c- di-GMP level through increased phosphodiesterase activity. Altogether, these findings suggest that CPEJ as a biofilm inhibitor has new potential for pharmacological (e.g. drug and medication) and industrial applications (e.g. ship hulls, water pipes, and membrane processes biofouling control).

Automated summary

Biofilms, composed of bacteria and extracellular polymeric substances (EPSs), increase antibiotic resistance by hindering antibiotic transport to bacterial cells. Citrus peel extract from Jeju Island (CPEJ) was found to inhibit biofilm formation without affecting bacterial growth. CPEJ reduced EPS production and increased bacterial motility. These effects were attributed to the reduction in intracellular cyclic di-guanosine monophosphate (c-di-GMP) levels through increased phosphodiesterase activity. This new finding suggests that CPEJ has potential as a biofilm inhibitor in pharmaceutical and industrial applications.