论文部分内容阅读
对出入境动物源性食品中分离的单增李斯特菌进行多位点序列分型(mutilocus sequence typing,MLST)分析,了解其序列型分布特点及不同菌株之间的亲缘关系。提取单增李斯特菌基因组DNA,选择其7个管家基因进行聚合酶链式反应扩增并测序。将测序结果截成标准序列的长度后上传到MLST数据库进行比对分析,获得7个管家基因的等位基因谱和序列分型编码,并将结果采用不加权算术平均组对(unweighted pair group method using arithmetic averages,UPGMA)法进行聚类分析。89株单增李斯特菌共获得51个STs,其中26个为新获得的STs(STnew1~STnew26);数量最多的5个STs为ST8(9.0%),ST121(9.0%)、ST7(5.6%)、ST87(5.6%)及新发现的STnew3(7.8%);其中ST456、ST34、ST343、ST19、ST517、ST201、ST98、ST330和ST73为在国内首次获得。采用UPGMA算法得到的进化树可将89株菌株分为3大类群,分类的结果与单增李斯特菌血清学家系分类结果一致。MLST结果对了解出入境动物源性食品中分离的单增李斯特菌的亲缘关系及流行病学溯源有重要意义。
Multilocus sequence typing (MLST) analysis of Listeria monocytogenes isolated from entry - exit animal - derived foods was carried out to understand the characteristics of its sequence distribution and the genetic relationship among different strains. The genomic DNA of Listeria monocytogenes was extracted and seven housekeeping genes were selected for PCR amplification and sequencing. The sequencing results were cut to the length of the standard sequence and then uploaded to the MLST database for alignment analysis. The allele and sequence typing codes of seven housekeeping genes were obtained and the results were analyzed using the unweighted pair group method using arithmetic averages, UPGMA) method. Among the 89 Listeria monocytogenes, 51 STs were obtained, of which 26 were newly acquired STs (STnew1 ~ STnew26); the most 5 STs were ST8 (9.0%), ST121 (9.0%) and ST7 ), ST87 (5.6%) and newly discovered STnew3 (7.8%). Among them, ST456, ST34, ST343, ST19, ST517, ST201, ST98, ST330 and ST73 were the first ones in China. The phylogenetic tree based on the UPGMA algorithm was used to classify 89 strains into three groups. The classification results are consistent with those of the Listeria monocytogenes family. The MLST results are important for understanding the genetic relationship and epidemiological tracing of Listeria monocytogenes isolated from entry-origin animal-derived foods.