Modulation of cell endogenous membrane potential by an external electrical field influences the structure and function of membrane compartments, proteins and lipid bi-layer. In this work, the effects of applied potential onSaccharomyces cerevisiae growth were characterized through simple yet conclusive experiments. Cell growth time profile and cell division were investigated as macroscopic response to the electrical stimulation. Control experiments were conducted under identical conditions except for the absence of applied potential. Through comparative analysis, electrical stimulation was verified to alter cell cycle as smaller sized population was observed, suggesting that a synchrony in cell division was promoted. Power spectral analysis was employed to sustain synchrony enhancement, and mathematical modeling was conducted for determining kinetic growth changes. Monod type kinetic parameters for growth were determined by non-linear regression. The affinity constant (namely kS) presented a dependence on applied potential suggesting changes on transport across cell membrane. Electrochemically promoted stress was also verified to inhibit growth as well as to induce changes on cell viability.
Key words: electrochemical stress, Saccharomyces cerevisiae, cell cycle, viability.
RESULTS AND DISCUSSION
Steady-state voltamograms were performed in order to evaluate the eletrochemical stability of the YPD medium, i.e. in what range the medium was eletrochemically stable. The obtained voltamograms are shown inFig. 1. No reaction involving glucose electrochemical reactions was detected in the whole voltamogram for three different glucose contents (2%, 10% and 20% w/v), attesting the stability of the main energy source at this potential range.
Additionally, it can be seen that the potential herein applied, +0.75 VSCE, is within the water stability zone. The voltamograms peaks observed in Fig. 1 are due to water decomposition (higher potential) and reduction of dissolved oxygen (lower potential). Thus, important changes on pH are avoided during S. cerevisiaepotentiostatically controlled growth at that potential.
ARAUJO, Ofelia Q.F. et al. Electrical stimulation of saccharomyces cerevisiae cultures.Braz. J. Microbiol. [online]. 2004, vol.35, n.1-2 [cited 2015-10-31], pp. 97-103 . Available from: <http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822004000100016&lng=en&nrm=iso>. ISSN 1678-4405. http://dx.doi.org/10.1590/S1517-83822004000100016.