本研究旨在探讨伤寒沙门菌(Salmonella enterica serovar Typhi, S. Typhi)中非编码RNA617(non-coding RNA617，ncRNA617)的分子特性，并研究其对生物膜形成的影响及作用机制。采用Northern blot方法检测ncRNA617的表达，通过cDNA 5’末端快速扩增技术(5’-rapid amplification of cDNA end，5’RACE)和逆转录-聚合酶链式反应(reverse transcriotion-polymerase chain reaction，3’RT-PCR)实验分析ncRNA617可能的转录起始位点和终止位点；构建ncRNA617缺陷菌株、回补菌株和过表达菌株等相关菌株，通过生物膜形成实验，观察ncRNA617对伤寒沙门菌生物膜形成的影响，并用实时荧光定量聚合酶链式反应(quantitative real-time polymerase chain reaction，qPCR)分析生物膜形成相关基因表达水平的变化，综合运用生物信息学方法预测ncRNA617和差异基因的结合区域，初步分析ncRNA617发挥调控作用的机制。结果显示，伤寒沙门菌确有ncRNA617的表达，长度约300 nt，其转录起始位点位于mig-14终止密码子下游967 nt处，终止位点位于t2681起始密码子上游 2 378～2 560 nt处。与野生对照菌株相比，ncRNA617缺陷菌株生物膜形成能力增强(P<0.05)，回补菌株的生物膜形成能力恢复至野生菌株水平，过表达菌株的生物膜形成能力有所下降(P<0.05)。qPCR结果表明，ncRNA617可负向调控多个生物膜形成相关基因的转录表达水平(P<0.05)。经生物信息学方法预测发现，ncRNA617与差异基因有不同的结合区域。本研究结果提示，ncRNA617在伤寒沙门菌中存在，其长度约270～452 nt。ncRNA617可能通过靶向结合生物膜形成相关基因下调基因表达，从而负向调控伤寒沙门菌生物膜的生成。

The purpose of this study is to investigate the molecular characteristics of non-coding RNA617 in Salmonella enterica serovar Typhi (S. Typhi), as well as its effect on biofilm formation and its mechanism. Northern blot was used to detect the expression of ncRNA617; 5’RACE (5’-rapid amplification of cDNA end) and 3’RT-PCR (reverse transcriotion-polymerase chain reaction) were used to identify possible transcription initiation and termination sites. ncRNA617 knockout strain, complemented strain and overexpression strain of S. Typhi were constructed. The bacterial biofilm formation experiment was used to observe the effect of ncRNA617 on the formation of biofilm; qPCR (quantitative real-time PCR) was used to analyze the effect of ncRNA617 on the expression level of genes related to biofilm formation. Northern blot showed the presence of ncRNA617 with a length of about 300 nt; 5’RACE and 3’RT-PCR revealed that the 5’end of the transcript was located at 967 nt downstream of the mig-14 stop codon, and the 3’end of the transcript was located at 2378-2560 nt upstream of start codon of t2681. Biofilm formation experiment showed that compared with wild control strain, the biofilm formation ability of the ncRNA617 knockout strain was enhanced (P<0.05). The biofilm formation ability of the complemented strain was restored to the level of the wild strain, and the biofilm formation ability of the overexpression strain decreased (P<0.05). qPCR results showed that ncRNA617 negatively regulated the transcriptional expression levels of several biofilm formation related genes. Predicted by bioinformatics methods, it was found that ncRNA617 had different binding regions with regulated genes. It is concluded that ncRNA617 exists in S. Typhi and its length is about 270～452 nt. ncRNA617 may negatively regulate gene expression by targeting genes related to biofilm formation, and then negatively regulates the biofilm formation of S. Typhi.