Kim Eiseul, Kim Hyun-Joong, Yang Seung-Min, Kim Chang-Gyeom, Choo Dong-Won, Kim Hae-Yeong
Institute of Life Sciences and Resources and Department of Food Science and Biotechnology, Kyung Hee University, Yongin 17104, Republic of Korea.
Department of Bioinformatics and Biosystems, Korea Polytechnics, Seongnam 13122, Republic of Korea.
J Microbiol Biotechnol. 2019 Apr 28;29(4):548-557. doi: 10.4014/jmb.1901.01046.
species have a ubiquitous habitat in a wide range of foods, thus the ability to identify staphylococci at the species level is critical in the food industry. In this study, we performed rapid identification of species using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight mass spectrometry (MALDI-TOF MS). MALDI-TOF MS was evaluated for the identification of reference strains ( = 19) and isolates ( = 96) from various foods with consideration for the impact of sample preparation methods and incubation period. Additionally, the spectra of isolated strains were analyzed using principal component analysis (PCA) and a main spectra profile (MSP)-based dendrogram. MALDI-TOF MS accurately identified reference strains and isolated strains: the highest performance was by the EX method (83.389.5% accuracy) at species level identification (EDT, 70.378.9% accuracy; DT, less than 46.3~63.2% accuracy) of 24-h cultured colonies. Identification results at the genus level were 100% accurate at EDT, EX sample preparation and 24-h incubation time. On the other hand, the DT method showed relatively low identification accuracy in all extraction methods and incubation times. The analyzed spectra and MSP-based dendrogram showed that the isolated strains were characterized at the species level. The performance analysis of MALDI-TOF MS shows the method has the potential ability to discriminate between species from foods in Korea. This study provides valuable information that MALDI-TOF MS can be applied to monitor microbial populations and pathogenic bacteria in the food industry thereby contributing to food safety.
葡萄球菌属在多种食物中广泛存在，因此在食品工业中，能够在种水平上鉴定葡萄球菌至关重要。在本研究中，我们使用基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）对葡萄球菌进行了快速鉴定。考虑到样品制备方法和培养时间的影响，对MALDI-TOF MS用于鉴定来自各种食物的19株参考菌株和96株分离株进行了评估。此外，使用主成分分析（PCA）和基于主要光谱图谱（MSP）的树状图对分离的葡萄球菌菌株的光谱进行了分析。MALDI-TOF MS准确鉴定了参考菌株和分离菌株：在24小时培养菌落的种水平鉴定中（EDT方法的准确率为70.3%78.9%；DT方法的准确率低于46.3%63.2%），EX方法的性能最高（准确率为83.3%~89.5%）。在EDT、EX样品制备和24小时培养时间下，属水平的鉴定结果准确率为100%。另一方面，DT方法在所有提取方法和培养时间下的鉴定准确率相对较低。分析的光谱和基于MSP的树状图表明，分离的葡萄球菌菌株在种水平上具有特征。MALDI-TOF MS的性能分析表明，该方法有潜力区分韩国食物中的葡萄球菌属菌种。本研究提供了有价值的信息，即MALDI-TOF MS可应用于监测食品工业中的微生物种群和病原菌，从而有助于食品安全。
