Evaluation of the antibacterial and antibiofilm activities of sodium benzoate against the soft rot disease of tomato in Iraq

Abstract

Pectobacterium carotovorum is one of the most serious pectolytic bacterial pathogens causing significant pre- and postharvest soft rot diseases on a variety of agroeconomic fruits and vegetables worldwide. Application of chemical pesticides for controlling the postharvest diseases is still insufficient and unacceptable by consumers. The effect of sodium benzoate (C6H5COONa) (SBN) was evaluated against the growth of P. carotovorum utilizing the highly pathogenic strain BR03, confirmed molecularly using dnaA primers. The inhibition zone was the greatest when P. carotovorum was treated with 600 mM SBN both at pH 7.5 and 7.0. Flow cytometry (distinguishing live and dead bacterial cells) and the development of bacterial colonies on Petri plates confirmed the bactericidal action of SBN. In addition, these results validated that bacterial cells were killed when treated with 600 mM SBN. The biofilm formation was completely inhibited and destroyed following exposure to 600 mM SBN after a 24-h incubation period and the absorbance readings were reduced as the concentration of SBN increased. Disease severity on inoculated tomato fruits decreased in comparison with the control fruit at either 4 or 25 °C. SBN is safe for human health and commonly used in industries as a food preservative. SBN can be an effective alternative method for controlling soft rot diseases on tomato fruits.