Study On Vegetables Polluted By Fecal Coliform Of Animal Slurry

In order to understand the present situation of vegetables polluted in NanJing, the number of Fecal Coliform (FC) of vegetables sampled from markets and farmland were investigated. Experiments with different treatments were carried out to detect the decrease of FC in vegetables. A pot experiment was conducted from March to May in 2006 to examine the number of FC of the soil and the exterior and interior in samples of Chinese cabbage, radish and lettuce which were cultured with different fertilizer measures and on different time. And investigate the quantity changes of FC in fresh livestock (Pig, Cattle , and chicken) feces and the soil (sampled in Yixing, Huaian and Nanjing) fertilized with animal slurry under natural preservation conditions in the summers and winters. And compare between colony counting method and multiple tube Fermentation method for counting the number of E.coli labeled with green fluorescent protein (GFP).The result indicates that the foliage vegetables were polluted severely by irritating fresh animal slurry directly, and vegetables were polluted severelyworse if the time between irritating and sampling was short. FC could be detected on the surface of raw vegetables and in the raw vegetables which were cooked simply. FC could not be detected on the surface of vegetables and in the vegetables only after they were steeped in the boiling water for a certain time, otherwise they are not safe as food.The exterior and interior of the vegetables were contaminated severely by the soil fertilized with the non-composting animal slurry, especially for the exterior of radish. The shorter interval between the appliance of fertilizer and planting, the more severe contamination the vegetables will be subjected to. The rhizosphere soil and non-rhizosphere soil were also contaminated by the non-composting animal slurry, the number of FC in soil was above 3.4 log CFU·g^-1 until the harvesting of vegetables. Irrigation could contaminate the soil and the exterior of Chinese cabbage and lettuce, but there is little difference between the two treatments.Under natural preservation conditions, the number of FC in fresh feces dropped rapidly than that of the soil in summer, the number of FC in both fresh feces and soil dropped slowly in winter than that of in summer, the number of FC in chicken feces and soil sampled from Huaian dropped fastest than others.Colony counting method and multiple tube Fermentation method for counting the number of E. coli labelled with green fluorescent protein have no statistical difference (p=0.376), It is suggested that the advantages of colony counting method will be exerted sufficiently for the samples with high microbe concentration.