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Title: Behavior of yeast cells in aqueous suspension affected by pulsed electric field
Authors: Zakhem, Henri El 
Lanoisellé, Jean-Louis
Lebovka, Nikolai I.
Nonus, Maurice
Vorobiev, Eugene
Affiliations: Department of Chemical Engineering 
Keywords: Electric fields
Aqueous suspensions
Electrical conductivity
Saccharomyces cerevisiae
Non-ionic surfactant
Triton X-100
Issue Date: 2006
Part of: Journal of colloid & interface science
Volume: 300
Issue: 2
Start page: 553
End page: 563
This work discusses pulsed electric fields (PEF) induced effects in treatment of aqueous suspensions of concentrated yeast cells (S. cerevisiae). The PEF treatment was done using pulses of near-rectangular shape, electric field strength was within E=2-5 kV/cm and the total time of treatment was t(PEF)=10(-4)-0.1 s. The concentration of aqueous yeast suspensions was in the interval of C(Y)=0-22 (wt%), where 1% concentration corresponds to the cellular density of 2x10(8) cells/mL. Triton X-100 was used for studying non-ionic surfactant additive effects. The electric current peak value I was measured during each pulse application, and from these data the electrical conductivity sigma was estimated. The PEF-induced damage results in increase of sigma with t(PEF) increasing and attains its saturation level sigma approximately sigma(max) at long time of PEF treatment. The value of sigma(max) reflects the efficiency of damage. The reduced efficiency of damage at suspension volume concentration higher than phi(Y) approximately 32 vol% is explained by the percolation phenomenon in the randomly packed suspension of near-spherical cells. The higher cytoplasmic ions leakage was observed in presence of surfactant. Experiments were carried out in the static and continuous flow treatment chambers in order to reveal the effects of mixing in PEF-treatment efficiency. A noticeable aggregation of the yeast cells was observed in the static flow chamber during the PEF treatment, while aggregation was not so pronounced in the continuous flow chamber. The nature of the enhanced aggregation under the PEF treatment was revealed by the zeta-potential measurements: these data demonstrate different zeta-potential signs for alive and dead cells. The effect of the electric field strength on the PEF-induced extraction of the intracellular components of S. cerevisiae is discussed.
DOI: 10.1016/j.jcis.2006.04.055
Ezproxy URL: Link to full text
Type: Journal Article
Appears in Collections:Department of Chemical Engineering

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