大肠杆菌对抗生素胁迫的响应及机制的初步探析

The primary exploration of the response and its mechanism of Escherichia coli to antibiotic stress

以大肠杆菌及氨苄青霉素、氯霉素、四环素三种抗生素为材料,初步研究了低浓度抗生素胁迫下大肠杆菌对抗生素的耐药性诱导、抗性稳定性、多重耐药性及抗性机理。结果显示大肠杆菌在3个实验周期内获得了对氨苄青霉素、氯霉素、四环素的耐药性,其耐药分别达到了90μg/mL、25μg/mL及49μg/mL。进一步研究表明大肠杆菌的耐药性能稳定遗传,且一种抗生素的胁迫作用可产生对多种抗生素的抗性。向抗生素胁迫作用的体系中添加N-乙酰半胱氨酸,当其添加量达到10 mmol/L及以上时,大肠杆菌失去了产生抗生素抗性的能力,初步证明大肠杆菌的抗性产生是由于抗生素诱导细胞内积累了活性氧,而活性氧促进了细菌DNA的突变。实验为细菌抗生素耐药性研究增添了新的证据,也为今后深入开展相关工作奠定了较好的基础。

Escherichia coli and ampicillin,chloramphenicol and tetracycline were used as materials to investigate the antibiotic resistant induction rate,resistance stability,multidrug resistance and its mechanism when Escherichia coli was under antibiotic stress.The results showed that E.coli was resistant to ampicillin,chloramphenicol and tetracycline within 3 cycles,and the resistance degree to the three antibiotics was 90μg/mL,25μg/mL and 49μg/mL,respectively.Further studies showed that E.coli was able to acquire stable and multiple inheritance of antibiotic resistance.Through adding N-acetyl-L-cysteine to the antibiotic-stressed system,and when its dosage was 10 mmol/L or more,E.coli lost its ability of antibiotic resistance,which proved that the resistance of E.Coli under antibiotic stress was due to the accumulation of reactive oxygen species(ROS),and ROS promoted the mutation of bacterial DNA.The results provided new evidences and foundation to study the bacterial antibiotic resistance.