Parisi Daniela, Magliulo Maria, Nanni Paolo, Casale Monica, Forina Michele, Roda Aldo
Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy.
Anal Bioanal Chem. 2008 Jul;391(6):2127-34. doi: 10.1007/s00216-008-2161-2. Epub 2008 May 17.
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a useful technique for the identification of bacteria on the basis of their characteristic protein mass spectrum fingerprint. Highly standardized instrumental analytical performance and bacterial culture conditions are required to achieve useful information. A chemometric approach based on multivariate analysis techniques was developed for the analysis of MALDI data of different bacteria to allow their identification from their fingerprint. Principal component analysis, linear discriminant analysis (LDA) and soft independent modelling of class analogy (SIMCA) were applied to the analysis of the MALDI MS mass spectra of two pathogenic bacteria, Escherichia coli O157:H7 and Yersinia enterocolitica, and the non-pathogenic E. coli MC1061. Spectra variability was assessed by growing bacteria in different media and analysing them at different culture growth times. After selection of the relevant variables, which allows the evaluation of an m/z value pattern with high discriminant power, the identification of bacteria by LDA and SIMCA was performed independently of the experimental conditions used. In order to better evaluate the analytical performance of the approach used, the ability to correctly classify different bacteria, six wild-type strains of E. coli O157:H7, was also studied and a combination of different chemometric techniques with a severe validation was developed. The analysis of spiked bovine meat samples and the agreement with an independent chemiluminescent enzyme immunoassay demonstrated the applicability of the method developed for the detection of bacteria in real samples. The easy automation of the MALDI method and the ability of multivariate techniques to reduce interlaboratory variability associated with bacterial growth time and conditions suggest the usefulness of the proposed MALDI MS approach for rapid routine food safety checks.
基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）是一种基于细菌特征蛋白质质谱指纹图谱进行细菌鉴定的有用技术。为了获得有用信息，需要高度标准化的仪器分析性能和细菌培养条件。开发了一种基于多变量分析技术的化学计量学方法，用于分析不同细菌的MALDI数据，以便从其指纹图谱中识别细菌。主成分分析、线性判别分析（LDA）和类类比软独立建模（SIMCA）被应用于分析两种病原菌大肠杆菌O157:H7和小肠结肠炎耶尔森菌以及非致病性大肠杆菌MC1061的MALDI MS质谱。通过在不同培养基中培养细菌并在不同培养生长时间进行分析来评估光谱变异性。在选择了具有高判别力的相关变量以评估m/z值模式后，通过LDA和SIMCA进行细菌鉴定，与所使用的实验条件无关。为了更好地评估所使用方法的分析性能，即正确分类不同细菌的能力，还研究了六株大肠杆菌O157:H7野生型菌株，并开发了一种经过严格验证的不同化学计量学技术的组合。对加标牛肉样品的分析以及与独立化学发光酶免疫分析的一致性证明了所开发方法在实际样品中检测细菌的适用性。MALDI方法易于自动化，多变量技术能够降低与细菌生长时间和条件相关的实验室间变异性，这表明所提出的MALDI MS方法对于快速常规食品安全检查是有用的。
