MALDI-TOF-MS对金桔表面肠杆菌科微生物分布的研究

为了评估金桔的食用风险,试验采用基质辅助激光解吸电离飞行时间质谱法(MALDI-TOF-MS)调查金桔表面肠杆菌科微生物分布情况,筛选致病微生物,同时采用与生化鉴定和16S rDNA测序鉴定辅助鉴定结果。实验共分离6种的肠杆菌科细菌,分别为日沟维肠杆菌、分散泛菌、肺炎克雷伯菌、阪崎肠杆菌、生癌肠杆菌、阴沟肠杆菌,其中分散泛菌、阴沟肠杆菌和肺炎克雷伯菌出现频率较高;对三种鉴定方法进行比较分析,MALDI-TOF-MS鉴定结果与另外两种与属水平一致,种水平有偏离;MALDI-TOF-MS对分离微生物进行聚类分析表明同属微生物亲缘较近,同种微生物峰谱图仍有差异。试验结果表明,金桔表面具有肠道致病微生物,有一定食用风险,建议加强农产品致病菌常规的检测及风险评估力度;MALDI-TOF-MS方法可分辨率高且能提供基于蛋白质水平归类分析可以用于农产品微生物的快速检测。

Distribution of Enterobacteriaceae on Kumquat Surface by MALDI-TOF-MS

To evaluate the consumption risk of kumquat, MALDI-TOF-MS was adopted to investigate the distribution of Enterobacteriaceae on kumquat surface by screening the pathogenic microorganisms, which were identified by biochemical identification and 16S rDNA sequencing identification to confirm the results. Six species of Enterobacteriaceae were isolated and identified as Enterobacter gergoviae, Klebsiella pneumonia, Enterobacter sakazakii, Pantoea dispers, Enterobacter cloaca and Enterobacter cancerogenus, among which Klebsiella pneumonia, Enterobacter cancerogenus and Enterobacter sakazakii had high detection rates. The results of MALDI-TOF-MS were consistent with those of the two other methods on genus but partly different on species. The cluster analysis of isolated microorganisms by MALDI-TOF-MS showed that the microorganisms of the same genus were comparatively close relatives; however, microorganisms of the same species had some differences in mass spectrums. The results indicated that there were Enteropathogens on the surface of kumquats, which resulted in a consumption risk. Enhancing the routine detection and risk assessment of pathogens in agricultural products was suggested. , MALDI-TOF-MS could be used for rapid detection of agricultural microorganisms with the advantages of high resolution and classification analysis on the basis of protein level.