几种杀螺细菌的筛选与功效研究

湖北钉螺是日本血吸虫的唯一中间宿主，生物杀螺具有环保、成本较低以及对钉螺定向特异的优点。从鄱阳湖草洲土壤及病螺体内分离出4株对钉螺具有高毒性作用的细菌。革兰氏染色和显微镜观察表明，一株为芽孢杆菌，其余3株均为革兰氏阴性杆菌。16srDNA扩增及序列比对鉴定其种属类型，结果显示分别为Enterobactersp．、B．cereus、S．putrefaciens和Aeromonassp．。杀螺研究结果表明，4株细菌的发酵液、发酵上清液和菌体对钉螺均表现出不同程度的毒杀作用，其中S．putrefaciens和Aeromonassp．的杀螺效果最好，72h发酵液和发酵上清液对钉螺的毒杀作用分别达100％和95％以上。各细菌发酵上清SDS-PAGE结果发现了丰富蛋白带，推测这些蛋白中存在对钉螺具有毒杀功效的组分。

Screening and toxicity of bacteria for killing Oncomelania hupensis

Oncomelania hupensis is the only intermediate host of Schistosomiasis Japonicum, so to kill it is the useful way to control Schistosomiasis. The biological method had advantages such as safe, low cost and specificity to snails. 4 strains of bacteria which were high toxic to Oncomelania hupensis were screened from the soil of grass-terra around Poyang lake and sick snail bodies. The study of Gram method staining and microscope indicated that 3 strains were gram negative bacilliform bacteria and one was Belong to bacillus. The PCR amplification of 16s rDNA and sequence analysis revealed which were classed to Enterobacter sp. ,B. cereus, S. putrefaciens, Aeromonas sp. , respectively. The results of killing snails test showed that 4 strains of bacteria components including the ferment liquid, ferment supernatant and bacteria were different toxic to snails. Among them, the toxicity of the ferment liquid and ferment supematant of S. putrefaciens and Aeromonas sp. showing effectively killing snails achieved 100% and over 95% after 72h respectively. SDS-PAGE of bacteria ferment components discovered that many proteins existed in ferment supematant and it might be responsible for its property of killing snails.