The inhibitory effect of phloretin on the formation of Escherichia coli O157:H7 biofilm in a microfluidic system

Abstract

A rapid and simple multiplex method to simultaneously investigate the effects of candidate drugs on the prevention of biofilm formation and to screen the biological activity of antimicrobial agents is urgently needed. Although several types of tools have been proposed for this purpose, conventional methods are still complicated and require long analytical times. This study presents a microfluidic approach to analyze the effect of phloretin on the formation of enterohemorrhagic E. coli O157:H7 biofilm in a single experiment. The microfluidic device is able to generate a continuous concentration gradient of phloretin in the main detection channel. Unlike conventional methods, this technique allows the analysis of the biofilm form of E. coli O157:H7 as an opportunistic pathogen and model organism; subsequently, mature biofilms were treated with phloretin to investigate the minimal biofilm eradication concentration (MBEC). In addition, inhibition assay of bacterial biofilm under concentration gradient is able to screen full concentration instead of point-to-point concentration assay. The results of MBEC determination clearly confirm that a low concentration of the antioxidant phloretin (30–35 μ/mL) significantly reduces biofilm formation, which suggests that phloretin acts as a biofilm inhibitor of E. coli O157:H7. The microfluidic approach for the evaluation of drug candidates could provide important information for the treatment of patients with chronic infection.