Adaptive silver resistance in Cupriavidus metallidurans
(2013)
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- Assessing and controlling microbial contamination during long-term manned spaceflight is of paramount importance as contamination can cause problems for the astronaut’s health and the infrastructure of the space station. Strains from the β-proteobacterial genera Cupriavidus and Ralstonia were identified and isolated during numerous monitoring campaigns from different space-related environments. This study aimed to gather more insights in the ability of these strains to thrive in these environments. All isolates acquired moderate to high tolerance against several stressors and can grow in oligotrophic conditions, enabling them to persist in the International Space Station and related environments in spite of the implemented disinfection and sterilization procedures. An important part of this study investigated the silver resistance mechanisms of the isolates, as silver is used to sanitize water sources in space. All isolates tolerated silver concentrations higher than those regularly measured in the drinking water aboard the ISS, and survived a 23-month exposure to silver in drinking water. Furthermore, rapid evolution towards significantly increased silver resistance (> 10-fold compared to the parental strain) was observed in C. metallidurans strains. Interestingly, the identified silver efflux pumps did not participate in this adaptive response. By contrast, the agrS gene coding for the histidine kinase of the two-component regulatory system AgrR-AgrS was shown to be affected either by an insertion sequence element or by point mutation, resulting in the increased transcriptional expression of the response regulator AgrR. AgrR on its turn cross-activated the expression of mmmQ coding for a small periplasmic protein, resulting in the increased silver resistance.
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Mijnendonckx, K. (2013). Adaptive silver resistance in Cupriavidus metallidurans. https://hdl.handle.net/2078.5/52852