不同热处理对沙门氏菌DNA消亡的影响

Effect of Heat Treatment on the Demise of Salmonella DNA

为研究各种热处理方式对沙门氏菌DNA消亡及其检测效果的影响,选择肉品加工和消费过程中常用的热处理方式对沙门氏菌进行处理。灭活后的菌体室温放置一定时间后分别提取基因组DNA,并进行分析。结果表明:65℃20min、85℃30min、沸水浴3min、121℃15min处理均能使沙门氏菌完全灭活,其中65℃20min、85℃30min处理后菌液中残存有大量的基因组DNA,且消亡速度缓慢,放置18d后仍有可见条带。沸水浴3min处理后菌液中基因组DNA条带微弱,放置4d后即消失。121℃15min处理后则无可见条带。沸水浴2min处理后不能使菌液中的沙门氏菌完全失活。65℃20min、85℃30min、沸水浴3min、121℃15min致死后的菌液中在很长一段时间内存在有大量的基因片段。加热温度越高、时间越长,沙门氏菌DNA消亡速度越快。因此,肉品在沸水中至少加热3min以上才能保证安全;热处理后残留的基因片段对应用DNA分析检测沙门氏菌产生很大的干扰作用,影响检测结果的准确性。

In order to explore the impact of a variety of heat treatments on the detection and extinction of Salmonella DNA,five kinds of common heat treatment methods during the processing and consumption of meat were applied to kill Salmonella.The genomic DNA of treated bacteria after a period of storage at room temperature was extracted.The results showed that heat treatment at 65 ℃ for 20 min,85 ℃ for 30 min,boiling for 3 min,and sterilization at 121 ℃ for 15 min could completely inactivate Salmonella,but boiling for 2 min cannot inactivate Salmonella.A large number of genomic DNA remained in bacilli treated by heating at 65 ℃ for 20 min and 85 ℃ for 30 min,and exhibited a slow demise as well as the bands was still visible after storage for 18 days.The DNA bands of bacilli treated by boiling for 3 min was very weak and disappeared after four days.In contrast,the sterilization at 121 ℃ for 15 min had no visible bands.During a long storage period,a large number of gene fragments also remained in dead bacilli.The higher heating temperature resulted in the faster degeneration of Salmonella DNA.Therefore,in order to keep safety,the meat should be boiled for at least 3 min.