Non-thermal methods to disinfect enterohemorhagic Escherichia coli contamination in salad vegetables

将含有绿色荧光蛋白基因的质粒转化肠出血性大肠杆菌O 157。通过将叶子浸泡在细菌的悬浮液中，生产出了被细菌污染的莴苣。忽略预先存在的细菌植物群，在紫外光照射下准确计数O 157的数量。在整个研究过程中，对各种化学试剂和处理条件的消毒效果进行了检查。加热的贝壳粉溶液对生菜的杀菌活性强于次氯酸盐。一部分接种物似乎已侵入到药物难以到达的生菜组织内部，完全杀灭了O 157菌，将生菜浸泡在贝壳粉溶液中低温保存8-24 h，即可杀灭O 157菌。生物保藏是一种很有吸引力的食品安全方法。虽然从人粪便标本中分离出对O 157有抑制作用的细菌，但在整个实验过程中，在食物的正常细菌植物群中没有发现这种细菌。初步试验表明，脉冲功率放电有可能降低生菜O 157污染水平。

A strain of enterohemorrhagic Escherichia coil O157 was transformed by the plasmid which contained the green fluorescence protein gene. Artificially contaminated lettuce was produced by soaking the leaves in the suspension of the bacterium. Neglecting preexisting bacterial flora the number of O157 were accurately counted for their fluorescence under irradiation of UV. Throughout this research various kinds of chemical reagents and treatment-conditions were examined for disinfecting effects. Heated shell-powder solution showed strong bactericidal activity on lettuce rather than hypochlorite. A part of the inoculum seemed to have invaded to lettuce organization inside where the drug is difficult to reach and perfectly kills it. The O157 organisms were killed in 8-24 hour, when the lettuce was preserved at the low temperature after soaking in the shell-powder solution. Biopreservation is becoming attractive method for food safety. Although bacteria showing inhibitory effects against O157 were isolated from the human fecal specimens, it was not found among normal bacterial flora of foods throughout the experiments. It was suggested through some preliminary experiments that pulsed power electric discharge could possibly reduce the level of O157 contamination on lettuce.