Abstract

RUEDA, Carolina et al. Evaluating the presence of the mer A gene implied in mercury detoxification from native actinomycete strains from La Conejera wetlands. Rev. colomb. biotecnol [online]. 2009, vol.11, n.2, pp.105-113. ISSN 0123-3475.

Ten native actinomycete strains were isolated from water and sediment samples collected in La Conejera wetlands to assess mercury resistance and detoxification ability for evaluating the presence of the mer A gene involved in that process. Sensitivity assays were performed using 3.68 x 10^-3 mM to 10 mM HgCl₂ concentrations. Growth curves were generated for each resistant strain after 192 h in discontinuous fermentation in medium supplemented with 0.01 mM and 0.05 mM HgCl₂. Biomass growth was then measured by dry weight, maximum value (2.37 g•L^-1) being obtained after 72 h. Primer pairs were designed based on the sequence encoding the mercury-reductase enzyme in Streptomyces lividans 1326. PCR conditions for amplifying that region were standardised. The mer A gene was identified in the KH7 strain, resulting in an amplified product of around 686 bp. The KH7 strain electrophoresis profile obtained by pulsed field gel electrophoresis showed 50, 90 and 300 Kb plasmid DNA which could be related to metal resistance in this strain.

Keywords : Streptomyces; mercury-resistance; mer A gene; plasmid; wetlands.

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