BACKGROUND The traditional method of bacterial identification based on 16S rRNA is a widely used and very effective detection method, but this method still has some deficiencies, especially in the identification of closely related strains. A high homology with little differences is mostly observed in the 16S sequence of closely related bacteria, which results in difficulty to distinguish them by 16S rRNA-based detection method. In order to develop a rapid and accurate method of bacterial identification, we studied the possibility of identifying bacteria with other characteristic fragments without the use of 16S rRNA as detection targets. RESULTS We analyzed the potential of using cas (CRISPR-associated proteins) gene as a target for bacteria detection. We found that certain fragment located in the casx gene was species-specific and could be used as a specific target gene. Based on these fragments, we established a TaqMan MGB Real-time PCR method for detecting bacteria. We found that the method used in this study had the advantages of high sensitivity and good specificity. CONCLUSIONS The casx gene-based method of bacterial identification could be used as a supplement to the conventional 16 s rRNA-based detection method. This method has an advantage over the 16 s rRNA-based detection method in distinguishing the genetic relationship between closely-related bacteria, such as subgroup bacteria, and can be used as a supplement to the 16 s rRNA-based detection method.

中文翻译：

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一种基于casx基因定量检测干酪乳杆菌的新方法及其应用。

背景技术传统的基于16S rRNA的细菌鉴定方法是一种被广泛使用且非常有效的检测方法，但该方法仍存在一些不足，特别是在密切相关菌株的鉴定中。在密切相关的细菌的16S序列中大多观察到高度同源性，几乎没有差异，这导致难以通过基于16S rRNA的检测方法区分它们。为了开发一种快速，准确的细菌鉴定方法，我们研究了在不使用16S rRNA作为检测目标的情况下鉴定具有其他特征片段的细菌的可能性。结果我们分析了使用cas（CRISPR相关蛋白）基因作为细菌检测目标的潜力。我们发现位于casx基因中的某些片段是物种特异性的，可以用作特定的靶基因。基于这些片段，我们建立了TaqMan MGB实时PCR方法来检测细菌。我们发现本研究中使用的方法具有灵敏度高和特异性好的优点。结论基于casx基因的细菌鉴定方法可作为常规基于16 s rRNA的检测方法的补充。该方法与基于16 s rRNA的检测方法相比，在区分紧密相关的细菌（例如亚群细菌）之间的遗传关系方面具有优势，并且可以用作基于16 s rRNA的检测方法的补充。我们发现本研究中使用的方法具有灵敏度高和特异性好的优点。结论基于casx基因的细菌鉴定方法可作为常规基于16 s rRNA的检测方法的补充。该方法与基于16 s rRNA的检测方法相比，在区分紧密相关的细菌（例如亚群细菌）之间的遗传关系方面具有优势，并且可以用作基于16 s rRNA的检测方法的补充。我们发现本研究中使用的方法具有灵敏度高和特异性好的优点。结论基于casx基因的细菌鉴定方法可作为常规基于16 s rRNA的检测方法的补充。该方法与基于16 s rRNA的检测方法相比，在区分密切相关的细菌（例如亚群细菌）之间的遗传关系方面具有优势，并且可以用作基于16 s rRNA的检测方法的补充。