Bogdanova E S, Bass I A, Minakhin L S, Petrova M A, Mindlin S Z, Volodin A A, Kalyaeva E S, Tiedje J M, Hobman J L, Brown N L, Nikiforov V G
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.
Center of Microbial Ecology, Michigan State University, East Lansing, MI, USA.
Microbiology (Reading). 1998 Mar;144 ( Pt 3):609-620. doi: 10.1099/00221287-144-3-609.
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.
负责对有毒污染物产生抗性的基因的水平传播，可能在细菌群体适应环境污染物的过程中发挥关键作用。然而，在自然环境中基因传播的频率和范围尚不清楚。本文报道了两种不同的汞抗性（mer）操纵子变体在广泛地理区域内的不同芽孢杆菌及相关物种之间自然发生的水平传播。一种mer变体编码具有单个N端结构域的汞还原酶，而另一种编码具有重复N端结构域的还原酶。含有前一种mer操纵子类型的菌株对有机汞敏感，在本研究中所研究的陆地抗汞芽孢杆菌群体中最为常见。含有后一种操纵子类型的菌株对有机汞具有抗性，在文献中先前描述的水俣湾抗汞芽孢杆菌群体中占主导地位。至少三种不同的转座子（与来自临床肠球菌菌株的II类万古霉素抗性转座子Tn1546相关）和接合质粒被认为是这些mer操纵子传播的介导者。
