定量竞争性RT-PCR检测耐受山梨酸钾的大肠杆菌菌株中acrA-mRNA表达水平  

Quantitative competitive RT-PCR and quantitative detection of acrA-mRNA in tolerant isolates of E.coli induced by potassium sorbate

作　　者：陈爱美[1,2] 施庆珊[1,2] 谢小保[1,2] 欧阳友生[1,2] 陈仪本[1,2] 

机构地区：[1]广东省微生物研究所,广州510070 [2]广东省菌种保藏与应用重点实验室,广州510070

出　　处：《中国食品添加剂》2008年第3期154-159,124,共7页China Food Additives

摘　　要：采用含有亚抑菌浓度(1/2×MIC)山梨酸钾的LB琼脂平板连续传代的方法,对大肠杆菌(Escherichia coli)进行诱导,获得具有一定耐受性的大肠杆菌菌株;通过定量竞争性RT-PCR检测诱导后的各个菌株与未经诱导的各个菌株的acrA-mRNA的表达水平。结果表明,各个菌株经过含有亚抑菌浓度山梨酸钾的LB琼脂连续培养10代后获得的诱导菌株,与普通LB琼脂平板连续培养10代后获得的菌株相比可以耐受更高浓度的山梨酸钾,并且acrA-mRNA表达水平在诱导后的各个菌株中比未经诱导的各个菌株均有一定程度的提高。说明大肠杆菌主动外排系统AcrAB-TolC中acrA基因的表达水平提高可能与大肠杆菌对山梨酸钾的耐受程度增加有一定相关性。Four strains of Escherichia coli were cultured in LB agar containing potassium sorbate of sub-inhibitory concentration （ 1/2 × MIC） and LB agar without potassium sorbate for 10 days, and inoculated repeatedly every 24 hours to induce the tolerant isolates. Detected the MICs of induced and uninduced strains of E. coli. A Quantitative Compet, itive RT-PCR was established to study the different levels of acrA-mRNA in induced and uninduced strains of E. coli. Results revealed that the MICs of induced and uninduced strains didnt changed very much in first 24 hours, while the induced strains were more tolerant to high concentration of potassium sorbate than the uninduced strains with culturing time protracted. The levels of acrA-mRNA in induced strains were higher than the wild strains to some extent. The tolerance of E. coli to potassium sorbate may be enhanced by stimulation with sub-inhibitory concentration of potassium sorbate for long and the increasing expression of acrA-mRNA in E. coli maybe facilitate the appearance of tolerant isolate.

关 键 词：定量竞争性RT—PCR 亚抑菌浓度 山梨酸钾 耐受性 acrA—mRNA 

分 类 号：TS207[轻工技术与工程—食品科学]