Abstract：Objective To demonstrate the effects of symbiotic bacteria from lettuce on inactivation of norovirus（NV）.Methods Symbiotic bacteria were isolated from the lettuces sampled from farmlands and supermarkets. NV mixed with symbiotic bacteria was set as the experimental group,without symbiotic bacteria as the control group. After the inactivation by high temperature,ultraviolet light（UV）and chlorine dioxide,the ratio of NV amount in the experimental group and the control group was calculated to evaluate the effects of symbiotic bacteria. The mechanism of symbiotic bacteria was revealed by detecting their effects on the protection of viral capsid protein from UV and on the adsorption of NV.Results Eleven symbiotic bacteria were identified from lettuces,all of which were bacilli,mainly Pseudomonas. Ten symbiotic bacteria could improve the heat-resistant ability of NV,with Microbacterium oryzae,Cupriavidus taiwanensis（SC061204）,Pseudomonas furukawaii,Enterobacter tabaci and Pseudomonas resinovorans（SC061211）more significant. Eleven symbiotic bacteria could improve anti-UV ability of NV,with Pseudomonas putida,Microbacterium oryzae and Enterobacter tabaci more significant. Only one strain of Pseudomonas putida could improve anti-chlorine dioxide ability of NV（Class I hazard）. Pseudomonas putida,Microbacterium oryzae and Enterobacter tabaci could significantly reduce the damage of NV capsid protein. Nine symbiotic bacteria could promote NV adsorption into lettuces,with the promotion rates ranged from 1.04% to 46.73%;while Pseudomonas putida and Pseudomonas resinovorans（SC061211） could restrain NV absorption,with the promotion rates of -6.50% and -19.85%.Conclusion Symbiotic bacteria from lettuce may enhance the anti-inactivation of NV by protecting capsid protein and promoting adsorption of NV. It is recommended to control the presence of symbiotic bacteria in the process of inactivating NV.
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