Effectiveness of reuterin alone and in combination with nisin or other food contact surfaces sanitizers and cleaners for disinfection of stainless steel surfaces contaminated with Escherichia coli and Listeria innocua.

The efficacy of reuterin as disinfectant individually or in combination with nine disinfectants and cleaning agents or bacteriocin nisin was evaluated against planktonic cells and biofilms (stainless steel) of E. coli k12 and L. innocua. Maximum effect of each compound or their formulation with reuterin was determined at room temperature after 30 s and 5 min. In planktonic cells, after 30 s of the exposure to reuterin (200 Au/ml), the levels of viable cells of E. coli and L. innocua decreased by 1.2 and 0.65 log 10 cfu/ml, respectively. The inhibitory effect of reuterin against both organisms was enhanced significantly by adding sodium hypochlorite (NaOCl, 0.15%) followed by phosphoric acid (H 3 PO 4 ,1%) and nisin (60 IU/ml) whereas, combination with sodium dodecyl benzene sulfonate (SDBS, 0.06%) only pronounced the effect against L. innocua. This might be indicated by the presence of synergistic effect between reuterin and these substances. At the end of exposure time (5 min), reuterin led to a total destruction effect of E. coli while L. innocua was reduced by 5.2 log 10 cfu/ml. Interaction between reuterin and dimethyl ethyl benzyl ammonium chloride (BAC, 0.06%) or sodium hydroxide (NaOH, 1%) or peracetic acid (PAA, 0.03%) decreased their immediate effect (30 s), however, in except of PAA treatment, at the end of exposure time, total population destruction of both organisms was obtained. The addition of sodium dodecyl sulfate (SDS, 0.06%) or hydrogen peroxide (H 2 O 2 , 1%) or tri-sodium sulfate (TSF, 9.5%) to reuterin did not improve its inhibitory effect. In surface test, a similar disinfecting effect of reuterin against both organisms contaminated soiled stainless steel surfaces was obtained. A combination of reuterin and nisin or NaOCl had a disinfecting effect against biofilms compared to planktonic cell test. It is concluded that reuterin alone and its formulation with NaOCl or nisin could be used to develop an effective disinfectant system able to decontaminate successfully food contact surfaces and to prevent the development of bacterial resistances.