Department of Analytical Chemistry, Nutrition and Food Science, School of Veterinary Sciences/College of Biotechnology, University of Santiago de Compostela, Rúa Carballo Calero s/n, Campus Universitario Norte, E-27002 Lugo, Spain.
Food Microbiol. 2012 May;30(1):91-7. doi: 10.1016/j.fm.2011.10.012. Epub 2011 Oct 25.
Streptococcus parauberis is known as an etiological agent of mastitis in cows and for producing streptococcosis in farmed fish, although its presence in foods has seldom been reported. In this work, two bacterial isolates were recovered from a spoiled vacuum-packaged refrigerated seafood product. Both isolates were identified by 16S rRNA gene sequencing, exhibiting 99% homology with respect to S. parauberis. Both isolates were also characterized by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS). Genetic analysis revealed the clonal homogeneity of the isolates and their grouping together with other S. parauberis strains in a different cluster with respect to Streptococcus uberis strains. Proteomic analysis by MALDI-TOF MS allowed for the identification of five mass peaks in the range of 2200-6000 m/z that resulted to be specific to the species S. parauberis and allowed its rapid and direct identification with respect to other pathogenic and spoilage bacteria potentially present in seafood and other food products. This study represents, to our knowledge, the first report of S. parauberis in seafood in general and in vacuum-packed food products in particular. Moreover, it provides a rapid method based on MALDI-TOF MS for the identification of S. parauberis.
副猪链球菌是已知的奶牛乳腺炎的病原体，并能导致养殖鱼类的链球菌病，尽管其在食品中的存在很少被报道。在这项工作中，从变质的真空包装冷藏海鲜产品中分离出两株细菌。通过 16S rRNA 基因测序鉴定这两株菌，与副猪链球菌的同源性为 99%。两株菌也通过基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）进行了鉴定。遗传分析显示，这些分离株具有克隆同源性，并且与其他副猪链球菌菌株一起在不同于停乳链球菌菌株的不同聚类中分组。MALDI-TOF MS 的蛋白质组学分析鉴定了五个质荷比范围在 2200-6000 m/z 的峰，这些峰对副猪链球菌具有特异性，使其能够快速直接地与海鲜和其他食品中可能存在的其他致病性和腐败细菌进行区分。据我们所知，这项研究首次报道了副猪链球菌在一般海鲜中的存在，特别是在真空包装食品中。此外，它提供了一种基于 MALDI-TOF MS 的快速鉴定副猪链球菌的方法。
