探讨亚甲基蓝对革兰氏阴性菌肠出血性大肠杆菌O157的光动力杀伤作用及机理。通过细菌平板菌落计数法研究亚甲基蓝对肠出血性大肠杆菌O157的光动力杀伤作用,同时运用实时荧光定量PCR技术和聚丙烯酰胺凝胶电泳观察光动力技术对O157的基因组DNA的损伤程度和蛋白质降解效果。结果表明,当亚甲基蓝的浓度为10 mg/L,可见光(光功密度为200 mW/cm2)光照30 min时,几乎全部的肠出血性大肠杆菌O157能被杀死,并伴随有DNA断裂和蛋白质降解。亚甲基蓝对革兰氏阴性菌肠出血性大肠杆菌O157有非常明显的光灭活效应,其灭活机理可能是对基因组DNA的损伤以及蛋白质的降解。

The mechanisms of anti-microbial photodynamic technology(APDT) against Gram-negative bacteria Escherichia coli O157 by methylene blue(MB) was investigated.The bactericidal effect of MB-APDT on E.coli O157 was measured by counting the reduction of colony forming unit(CFU).The damage of DNA was observed by real-time polymerase chain reaction(RT-PCR) and the degradation of proteins was investigated by sodium dodecyl sulphate polyacrylamide gel electrophoresis(SDS-PAGE).Results showed that almost all of the E.coli O157 were photo inactivated by illumination with 30 min visible light(power density 200 mW/cm2) in the presence of 10 mg/L MB.The significant photo-inactivation of Gram-negative bacteria Escherichia coli O157 may be due to the damage of DNAs and the degradation of proteins.