2-tert-Butyl-1,4-benzoquinone, a food additive oxidant, reduces virulence factors of Chromobacterium violaceum

Multi-drug resistant bacteria have been paying increasing attentions. Quorum sensing (QS) and QS-associated biofilms are showing the vital reasons for antibiotics resistant. In this study, 2-tert-butyl-1,4-benzoquinone (TBQ), the oxidant of tert-butyl hydroquinone (TBHQ), can potentially be the QS inhibitor (QSI) of Chromobacterium violaceum ATCC12472. After treated with 50 μg/mL of TBQ, the violacein synthesis, chitinase, hemolysin and swimming motility of C. violaceum decreased by 70.6, 72, 70.5, and 88.45%, respectively. Further investigation demonstrated that combined TBQ (50 μg/mL) and ciprofloxacin (sub-MIC, 0.2 μg/mL) treatment not only inhibited biofilm formation by 73.27% but also improved the susceptibility of the biofilm to ciprofloxacin. The underlying mechanisms involved in the reduction of virulence factors and inhibition of biofilm formation were explored by quantitative real-time PCR, and confocal laser scanning microscopy (CLSM). The results showed that the expression levels of cviI, cviR, vioA, hsmP, chiA, and lolA were reduced by 51, 66, 49, 72, 77, and 72%, respectively. In addition, we determined that TBQ treatment could improve the survival rate of animal model Caenorhabditis elegans to 55.6% following infection with C. violaceum. Thus, food additive oxidant TBQ exhibits new QSI activity against C. violaceum and potential anti-biofilm application in food industry. •2-tert-Butyl-1,4-benzoquinone was first reported as a new quorum sensing inhibitor.•2-tert-Butyl-1,4-benzoquinone reduces virulence of Chromobacterium violaceum.•2-tert-Butyl-1,4-benzoquinone recovers the ciprofloxacin susceptibility of biofilm.•2-tert-Butyl-1,4-benzoquinone reduces the toxicity of C. violaceum to Caenorhabditis elegans.•2-tert-Butyl-1,4-benzoquinone can potentially resist biofilms in the food industry.