基质辅助激光解析飞行质谱法检测空肠弯曲菌及李斯特菌

Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry for the Detection of Campylobacter jejuni and Listeria monocytogenes

目的:通过VITEK MS微生物检测系统对养殖场及市售活鸡来源的空肠弯曲菌和单核细胞性李斯特菌进行激光解析飞行质谱鉴定,建立两种致病菌的质谱鉴定方法。方法:从样品中分离获得疑似的空肠弯曲菌和单核细胞性李斯特菌,经不同配比的基质液处理后进行质谱鉴定。通过分析检出菌特征峰及相对丰度差异来评价不同配比基质液对两种致病菌检测的影响。结果:空肠弯曲菌和李斯特菌对基质液配比要求具有明显差异,前者不需要经过甲酸裂解,而对三氟乙酸含量敏感,后者鉴定结果受到甲酸裂解制约。基质液含水量控制在体积分数30%可以有效避免特征峰缺失并提高检出率。结论:控制基质液的含水量、基质浓度和三氟乙酸含量可以增加空肠弯曲菌和李斯特菌的特征峰数量,增强相对丰度,提高致病菌检出率。基质液配比优化研究有助于增强食源性致病菌快速鉴定能力,有助于提高疾病预防和食源性风险监测的时效性。

Objective:To establish a matrix-assisted laser desorption ionization time of flight mass spectrometry(MALDITOF-MS)method to detect Campylobacter jejuni and Listeria monocytogenes in environmental samples from a chicken farm and samples from commercial live chickens using VITEK MS.Methods:The suspicious colonies of both bacteria were separated from the samples,and then suspended in matrix solutions consisting of mixtures of different proportions of ethanol,acetonitrile and water before identification by MALDI-TOF-MS.The effect of matrix solution composition on the bacterial detection was evaluated by examining the differences in characteristic peak value and relative abundance.Results:Significantly different matrix solutions were needed for the detection of Campylobacter jejuni and Listeria monocytogenes;the former did not require cracking by formic acid and was sensitive to trifluoroacetic acid(TFA),but the latter were just the opposite.A30%water content in matrix solution(V/V)could avoid the lack of characteristic peak and enhance the detection rate.Conclusion:Control of the water content in matrix solution,TFA concentration and matrix concentration can enhance the number and relative abundance of characteristic peaks,and detection rate.The optimized matrix solution enables the rapid identification of foodborne pathogens,which was able to improve the timeliness of disease prevention and food-borne risk monitoring.