Abstract
Cobalt is an important element with magnetic properties used in various industrial applications, but is also needed for biological activity. Very little is known about the cellular response of living systems to cobalt stress. Towards investigating this mechanism, we isolated individual Saccharomyces cerevisiae cells resistant to high cobalt concentrations up to 8 mmol l-1, by employing four different 'in vivo' evolutionary engineering strategies: selection under constant or gradually increasing stress levels, and selection under continuous or pulse exposure to cobalt stress. Selection under continuous exposure to gradually increasing cobalt stress levels yielded the most resistant cell population to cobalt. However, the resistance was highly heterogeneous within the mutant populations ranging from 3- to 3700-fold survival rate of isolated individuals to 8 mmol l-1 CoCl2 in the most resistant population. Moreover, cobalt-resistant individual colonies were associated with 2-4-times lower intracellular cobalt contents as compared to wild-type, and with cross-resistance to metals such as nickel, zinc, manganese, but not to copper and chromium ions. Contrary to mutants evolved under continuous exposure to cobalt, those isolated by pulse exposure strategy also exhibited resistance to heat shock and hydrogen peroxide stress. Taken together, this study reinforced the fact that evolutionary engineering is useful in selecting strains with very specific phenotypes, and further illustrated the importance of the strategy chosen to isolate the best evolved strain.
Original language | English |
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Pages (from-to) | 130-138 |
Number of pages | 9 |
Journal | Journal of Biotechnology |
Volume | 143 |
Issue number | 2 |
DOIs | |
Publication status | Published - 20 Aug 2009 |
Funding
We thank Aslı Baysal, Ülkü Yılmaz, Hüseyin Tayran, Çeşminaz Karabulut and Esma Nur Özkan for technical assistance. This work was supported in part by the Turkish State Planning Organization DPT (Advanced Technologies and ITU-ARINANOTEK 2008K120710), TUBITAK (105T314, to Z.P. Çakar), TUBITAK-EGIDE (PIA-BOSPHORUS 107T284, to Z.P. Çakar and J.M. François) and by NSF-MRSEC and ARO-DURINT projects at the University of Washington, Seattle (M. Sarikaya and C. Tamerler).
Funders | Funder number |
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NSF-MRSEC | |
TUBITAK | 105T314 |
TUBITAK-EGIDE | PIA-BOSPHORUS 107T284 |
Turkish State Planning Organization | ITU-ARINANOTEK 2008K120710 |
University of Washington |
Keywords
- Cobalt resistance
- Evolutionary engineering
- Population heterogeneity
- Saccharomyces cerevisiae