Horizontal spread of mer operons among Gram-positive bacteria in natural environments
Horizontal spread of mer operons among Gram-positive bacteria in natural environments
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DOI：
10.1099/00221287-144-3-609
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发表时间：
1998-03-01
期刊：
影响因子：
2.8
通讯作者：
Nikiforov, VG
中科院分区：
文献类型：
--
作者：
Bogdanova, ES;Bass, IA;Nikiforov, VG
负责对有毒污染物抗性的基因的水平传播可能在细菌种群对环境污染物的适应中起关键作用。然而，基因在自然环境中传播的频率和程度尚不清楚。据报道，两种不同的抗汞（mer）操纵子变体在广泛的地理区域内发生在多种芽孢杆菌和相关物种之间的自然水平传播。一种mer变体编码具有单个n端结构域的汞还原酶，而另一种mer变体编码具有重复n端结构域的还原酶。含有前操纵子类型的菌株对有机汞敏感，并且在本工作中研究的陆地抗汞芽孢杆菌种群中最常见。含有后一种操纵子类型的菌株对有机化合物具有抗性，并且在先前文献中描述的水俣湾抗汞芽孢杆菌种群中占主导地位。至少有三种不同的转座子（与临床肠球菌菌株的ii类万古霉素耐药转座子Tn1546有关）和共轭质粒被认为是这些mer操纵子传播的介质。
Horizontal dissemination of the genes responsible for resistance to toxic pollutants may play a key role in the adaptation of bacterial populations to environmental contaminants. However, the frequency and extent of gene dissemination in natural environments is not known. A natural horizontal spread of two distinct mercury resistance (mer) operon variants, which occurred amongst diverse Bacillus and related species over wide geographical areas, is reported. One mer variant encodes a mercuric reductase with a single N-terminal domain, whilst the other encodes a reductase with a duplicated N-terminal domain. The strains containing the former mer operon types are sensitive to organomercurials, and are most common in the terrestrial mercury-resistant Bacillus populations studied in this work. The strains containing the latter operon types are resistant to organomercurials, and dominate in a Minamata Bay mercury-resistant Bacillus population, previously described in the literature. At least three distinct transposons (related to a class ii vancomycin-resistance transposon, Tn1546, from a clinical Enterococcus strain) and conjugative plasmids are implicated as mediators of the spread of these mer operons.