Characterization of the Tn916 Conjugative Transposon in a Food-Borne Strain of Lactobacillus paracasei
Characterization of the Tn916 Conjugative Transposon in a Food-Borne Strain of Lactobacillus paracasei
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DOI：
10.1128/aem.00589-09
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发表时间：
2009-06-15
影响因子：
4.4
通讯作者：
Perozzi, Giuditta
中科院分区：
文献类型：
--
作者：
Devirgiliis, Chiara;Coppola, Doriana;Perozzi, Giuditta
食源性耐药乳酸菌在过去几年中受到越来越多的关注。我们最近在典型的意大利发酵乳制品Mozzarella di Bufala Campana的生产过程中使用的牛奶和天然乳清发酵剂培养物样品中发现了抗四环素的副干酪乳杆菌。在本研究中，我们在分子水平上表征了这些天然菌株中四环素抗性决定簇的遗传背景，我们将其鉴定为泰特（M）。该基因存在于21个独立的菌株，其指纹图谱分布在8个不同的重复基因外回文组的聚类分析。我们提供的证据表明，该基因与广泛的宿主，接合转座子Tn 916，这是以前从未被描述为发生在L。paracasei。通过使用专门设计的引物对的四个独立的分离株的PCR分析检测到存在环状中间形式的转座子，携带位于Tn 916的两个末端之间的偶联序列（GGCAAA）。这种新的偶联序列在与粪肠球菌的受体菌株JH 2 -2的交配实验中赋予低缀合频率。
Food-borne antibiotic-resistant lactic acid bacteria have received growing attention in the past few years. We have recently identified tetracycline-resistant Lactobacillus paracasei in samples of milk and natural whey starter cultures employed in the manufacturing process of a typical Italian fermented dairy product, Mozzarella di Bufala Campana. In the present study, we have characterized at the molecular level the genetic context of tetracycline resistance determinants in these natural strains, which we have identified as tet(M). This gene was present in 21 independent isolates, whose fingerprinting profiles were distributed into eight different repetitive extragenic palindromic groups by cluster analysis. We provide evidence that the gene is associated with the broad-host, conjugative transposon Tn916, which had never before been described to occur in L. paracasei. PCR analysis of four independent isolates by use of specifically designed primer pairs detected the presence of a circular intermediate form of the transposon, carrying a coupling sequence (GGCAAA) located between the two termini of Tn916. This novel coupling sequence conferred low conjugation frequency in mating experiments with the recipient strain JH2-2 of Enterococcus faecalis.