太平洋牡蛎中大肠杆菌净化的实验研究

静水中人工感染太平洋牡蛎,使其体内埃希氏大肠杆菌(Escherichia coli)浓度达到105 MPN/100g,然后放入紫外线循环系统中对其进行净化,研究贝水质量比(1∶3,1∶6,1∶10,1∶50)、水交换频率(1,3,5次/h)、温度(10,15,20,25℃)及净化层数(上层,中层,下层)等不同环境因子对牡蛎体内大肠杆菌净化的影响。在前6h大肠杆菌净化迅速,之后速度减慢,至36h时能净化2～3个对数值。不同环境因子的净化实验结果表明,当贝水比为1∶6,水交换律为3次/h,温度为15或25℃,净化层数为上层时净化效果最佳。

Effects of Different Factors on Depuration of Escherichia coli from Crassostrea gigas

This study examined the depuration of the Pacific oyster(Crassostrea gigas) in a flow-through depuration system under variable ratio of oysters to water(1∶3,1∶6,1∶10,and 1∶50),water exchange rate(1 time/h,3 times/h,and 5 times/h),temperature(10,15,20,and 25 ℃),and basket location(upper,middle,and lower).Pacific oysters were artificially contaminated with enteric microorganisms Escherichia coli to 105 MPN/100 g in still seawater,then depurated in 36-h trials.The number of E.coli in the oysters decreased sharply during the first 6 hours of depuration,then slowed down in the remaining time.After 36 hours,the number of E.coli declined to 2~3 log values.The results indicate that when ratio of oysters to water,water exchange rate,temperature,and basket location were 1∶6,3 times/h,15~25 ℃,and upper level,the greatest depuration rate of E.coli could be achieved in the oysters.