Electroporation Enhances the Metabolic Activity of Lactobacillus plantarum 564
Sanja Seratlić1*, Branko Bugarski1, Zorica Radulović2, Petr Dejmek3, Lars Wadsö4 and Viktor Nedović2
1University of Belgrade, Faculty of Technology and Metallurgy, Department of Chemical Engineering, Karnegijeva 4, RS-11120 Belgrade, Serbia
2University of Belgrade, Faculty of Agriculture, Department of Food Technology, Nemanjina 6, RS-11080 Belgrade, Serbia
3Lund University, Faculty of Engineering – LTH, Department of Food Technology, Engineering and Nutrition, P.O. Box 124, SE-22100 Lund, Sweden
4Lund University, Faculty of Engineering – LTH, Division of Building Materials, P.O. Box 118, SE-22100 Lund, Sweden
Article history:
Received March 19, 2013
Accepted June 26, 2013
Key words:
Lactobacillus plantarum, pulsed electric fields, isothermal calorimetry
Summary:
The exposure of bacterial cells to pulsed electric fields (PEF) leads to the reversible formation of pores in the cell membrane if an applied energy is below the critical level. Therefore, the effect of electric field pulses with amplitudes below 14 kV/cm and the applied energy up to 12.2 J/cm3 on the growth of Lactobacillus plantarum 564 cells was investigated. After PEF treatments, the growth of lactobacilli in De Man-Rogosa-Sharpe broth at 37 °C was monitored by isothermal calorimetry, absorbance and plate counts. All the applied treatments resulted in a higher growth rate of PEF-treated cells during early and mid-log phase, especially bacterial samples treated with lower field intensities (1.3–5.5 J/cm3). The transport of ions and molecules through the cell membrane (which facilitates the growth of electroporated lactobacilli) was particularly evident in the mid-exponential growth phase, where the doubling time was reduced more than 3 times after the exposure to electric pulses of 5.5 J/cm3. The heat production rate during the growth of electroporated cells was also higher, indicating the enhanced metabolic activity of PEF-treated cells. Moreover, the electroporated cells had a better acidification ability than the untreated ones. It can be summarized that the applied PEF treatments with an energy input of below 12 J/cm3 potentially induce reversible electroporation of the cell membrane, which has a positive impact on the growth and metabolic activity of the cells of lactobacilli.
*Corresponding author: 