Department of Analytical Chemistry, Nutrition and Food Science, School of Veterinary Sciences, University of Santiago de Compostela, Lugo, Spain.
Electrophoresis. 2013 Aug;34(15):2240-50. doi: 10.1002/elps.201200699. Epub 2013 Jul 15.
Enterococcus is a controversial genus due to its great variability; this genus includes pathogenic strains, spoilage strains, and apparently safe strains including some probiotic strains. Previous studies focused on the characterization of strains of Enterococcus spp. involved in nosocomial infections. However, little research has been conducted on Enterococcus strains in foodstuffs. In the present work, 36 strains of different species of Enterococcus have been characterized by means of MALDI-TOF MS, resulting in highly specific mass spectral fingerprints. Characteristic peak masses common to certain bacterial species of Enterococcus have been identified. Thus, a peak at m/z 4426 ± 1 was assigned as a genus-specific biomarker. In addition, phyloproteomic relationships based on the mass spectral data were compared to the results of a phylogenetic analysis based on the 16S rRNA gene sequence. A better grouping at the species level was observed in the phyloproteomic tree, especially for the Enterococcus faecium group. Presumably, the assortment of some strains or ecotypes could be related to their ecological niche specialization. The approach described in this study leads the way toward the rapid and specific identification of different strains and species of Enterococcus in food based on molecular protein markers, aiming at the early detection of pathogenic strains and strains implicated in food poisoning or food spoilage.
肠球菌是一个有争议的属，因为它具有很大的变异性；该属包括致病性菌株、腐败性菌株和显然安全的菌株，包括一些益生菌菌株。以前的研究集中于医院感染相关肠球菌属菌株的特征描述。然而，对于食品中的肠球菌菌株的研究较少。在本工作中，通过 MALDI-TOF MS 对 36 株不同种属的肠球菌进行了特征描述，得到了高度特异性的质谱指纹图谱。鉴定出某些肠球菌属细菌共有的特征峰质量。因此，将 m/z 4426 ± 1 处的峰指定为属特异性生物标志物。此外，基于质谱数据的系统发育蛋白质组学关系与基于 16S rRNA 基因序列的系统发育分析结果进行了比较。在系统发育蛋白质组树上观察到了更好的种水平分组，尤其是肠球菌粪亚种组。推测某些菌株或生态型的分类可能与其生态位特化有关。本研究中描述的方法为基于分子蛋白标记物快速、特异性鉴定食品中的不同肠球菌菌株和种属奠定了基础，旨在早期检测致病性菌株和与食物中毒或食品腐败相关的菌株。
