The Lactobacillus casei group, which includes the closely related species L. casei, L. paracasei, L. rhamnosus, and L. chiayiensis, has been under debate regarding its taxonomy because of the difficulty in distinguishing the species from each other. In the present study, we developed a novel real-time PCR assay for distinguishing the L. casei group species. The pan-genome, as determined by the genomes of 44 strains, comprised 6789 genes, comparative genomic analysis showed that L. casei group strains were classified by species. Based on these results, species-specific genes were identified, and primers were designed from those genes. Real-time PCR clearly distinguished each species of the L. casei group and specifically amplified only to the target species. The method was applied to 29 probiotic products, and the detected results and label claims were compared. Total 23 products were in accordance with the label claims, and the remaining products contained species different from those stated in the label claims. Our method can rapidly and accurately distinguish the L. casei group species in a single reaction. Hence, our assay can be applied to identify L. casei group species from food or environmental samples and to accurately determine the nomenclature of the species.

中文翻译：

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使用比较基因组学对干酪乳杆菌组种进行新型实时PCR分析。

干酪乳杆菌组（包括密切相关的干酪乳杆菌，副干酪乳杆菌，鼠李糖乳杆菌和嘉义乳杆菌）由于其分类上的困难而一直在争论中。在本研究中，我们开发了一种新颖的实时PCR分析方法，用于区分干酪乳杆菌群种。通过44个菌株的基因组确定的全基因组包含6789个基因，比较基因组分析显示干酪乳杆菌组菌株按物种分类。基于这些结果，鉴定了物种特异性基因，并从这些基因设计了引物。实时PCR清楚地区分了干酪乳杆菌群中的每个物种，并仅扩增为目标物种。该方法已应用于29种益生菌产品，并将检测到的结果和标签声明进行比较。总共有23种产品符合标签权利要求，其余产品所含物种与标签权利要求中所述的种类不同。我们的方法可以在单个反应中快速准确地区分干酪乳杆菌。因此，我们的测定方法可用于从食物或环境样品中鉴定干酪乳杆菌类物种，并准确确定该物种的命名法。