Transcriptomic Responses of Bacterial Cells to Sublethal Metal Ion Stress

Enhanced chromate reduction by resting Escherichia coli cells in the presence of quinone redox mediators

“…In the absence of these metal ions, 83.8% Cr(VI) (100 mg l À1 ) was reduced in 3 h, and about 6.0%, 39.5%, 64.3%, 94.4%, and 97.1% Cr(VI) were reduced in 3 h in the presence of 0.5 mM Cu 2+ , Ni 2+ , Co 2+ , Mn 2+ and Pb 2+ , respectively. The relatively less toxic Mn 2+ and Pb 2+ stimulated the mediated reduction process, indicating that they may be important for the activity of some proteins related to Cr(VI) reduction or help induce the expression of active reductases or cellular electron/substrate transporters (Hobman et al, 2007;Ma et al, 2009). The inhibition by Cu 2+ , Ni 2+ and Co 2+ was surprising since stimulation of chromate reductase activities and improvement of bacterial reduction of Cr(VI) by these cations has been reported previously (Desai et al, 2008;He et al, 2009;Sarangi and Krishnan, 2008).…”

Influence of Copper Resistance Determinants on Gold Transformation by Cupriavidus metallidurans Strain CH34

“…Once the metallic gold nanoparticles were formed, however, reactive oxygen species may no longer be produced (46). The determinants involved in metal or metalloid resistance that are upregulated after treatment with gold complexes are controlled by MerR-or ArsR-type regulators, which usually bind "soft" metals or metalloids (30,47,48). Gold complexes may cause here a gratuitous induction of determinants that may not deal with the noble metal (Table 5).…”

Transcriptomic response of Enterococcus faecalis to iron excess

“…It is possible that the stress response of blood exposed bacteria might be due to a secondary effect of iron deficiency, such as the impaired function of one or more metal dependent enzymes, which in turn might lead to the activation of stress responses. In fact, essential metals might induce cellular stress by deficit or excess (Hobman et al 2007). …”