Inhibition of Escherichia coli O157:H7 biofilm on vegetable surface by solid liposomes of clove oil

Escherichia coli O157:H7 (E. coli O157:H7) easily forms biofilms on pores and veins of plant, which poses a serious hazard to safety of ready-to-eat vegetables. Therefore, this study was designed to evaluate inhibition mechanism of clove oil on E. coli O157:H7 biofilm and apply it to vegetable for reduce risk of contamination. The results of crystal violet staining showed that clove oil could effectively remove biofilm. After treatment of biofilm with clove oil (2 MBIC), the results of resazurin method showed that bacterial metabolic activity decreased by 61.48%, and results of phenol-sulfuric acid method and Coomassie brilliant blue method showed that extracellular protein and polysaccharide content decreased by 62.76% and 47.5%, respectively. This indicates that clove oil can affect biofilm through above aspects. Finally, solid liposomes (SLPs) were prepared and applied to vegetables, which was first time that SLPs were used to remove biofilms. The results showed that clove oil SLPs exhibited excellent anti-biofilm activity at 4 degrees C and 25 degrees C without affecting senses and quality of vegetables. Therefore, the clove oil SLPs can exert a long-lasting antibacterial effect, effectively removing E. coli O157:H7 biofilm on vegetable surface, and prolonging the shelf life.