Multiple-locus sequence typing and analysis of toxin genes in Bacillus cereus food-borne isolates
Multiple-locus sequence typing and analysis of toxin genes in Bacillus cereus food-borne isolates
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DOI：
10.1128/aem.01495-07
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发表时间：
2008-02-01
影响因子：
4.4
通讯作者：
Giaccone, Valerio
中科院分区：
文献类型：
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作者：
Cardazzo, Barbara;Negrisolo, Enrico;Giaccone, Valerio
在本研究中，我们使用多位点序列分型 (MLST) 对 47 种食源性蜡状芽孢杆菌分离株进行了表征。新确定的序列与公共数据库中可用的序列相结合，以产生尽可能最大的数据集。对总共 296 个可获得 MLST 序列信息的菌株进行了系统发育分析，并鉴定了蜡状芽孢杆菌复合体中的三个主要谱系 - I、11 和 III。除少数例外，所有食源性分离株均属于第一组。通过多种统计方法分析了各种菌株之间水平基因转移（HGT）的发生，为蜡状芽胞杆菌内广泛的横向基因转移提供了证据。我们还研究了毒素编码基因的出现，重点关注它们在蜡状芽胞杆菌内的进化历史。确定了几种模式，表明 HGT 在毒素编码基因的进化中发挥着关键作用。我们的结果表明，HGT 是塑造蜡样芽孢杆菌复合体种群结构的重要因素。这里提出的结果也提供了蜡样芽孢杆菌复合体内网状进化的有力证据。
In the present study we characterized 47 food-borne isolates of Bacillus cereus using multilocus sequence typing (MLST). Newly determined sequences were combined with sequences available in public data banks in order to produce the largest data set possible. Phylogenetic analysis was performed on a total of 296 strains for which MLST sequence information is available, and three main lineages-I, 11, and III-within the B. cereus complex were identified. With few exceptions, all food-borne isolates were in group I. The occurrence of horizontal gene transfer (HGT) among various strains was analyzed by several statistical methods, providing evidence of widespread lateral gene transfer within B. cereus. We also investigated the occurrence of toxin-encoding genes, focusing on their evolutionary history within B. cereus. Several patterns were identified, indicating a pivotal role of HGT in the evolution of toxin-encoding genes. Our results indicate that HGT is an important element in shaping the population structure of the B. cereus complex. The results presented here also provide strong evidence of reticulate evolution within the B. cereus complex.