%0 Journal Article %A Bogdanova, E. S. %A Bass, I. A. %A Minakhin, L. S. %A Petrova, M. A. %A Mindlin, S. Z. %A Volodin, A. A. %A Kalyaeva, E. S. %A Tiedje, J. M. %A Hobman, J. L. %A Brown, N. L. %A Nikiforov, V. G. %T Horizontal spread of mer operons among Gram-positive bacteria in natural environments %D 1998 %J Microbiology, %V 144 %N 3 %P 609-620 %@ 1465-2080 %R https://doi.org/10.1099/00221287-144-3-609 %K mer operon %K Tn 1546, class II transposons %K Enterococcus %K horizontal gene transfer %K Bacillus %I Microbiology Society, %X 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, Tn 1546, from a clinical Enterococcus strain) and conjugative plasmids are implicated as mediators of the spread of these mer operons. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-144-3-609