Quantitative analysis of sublethally injured Saccharomyces cerevisiae cells induced by pulsed electric fields

- Method was proposed to quantify sublethally injured cells (SICs).
- SICs from intact and dead cells after PEF treatment were distinguished.
- PEF treatment parameters on ratio variation of SICs were investigated.
- Biological characteristics and potential value of SICs were discussed.

The survival states of Saccharomyces cerevisiae cells after being treated by pulsed electric field (PEF), intact, sublethally injured or dead, were quantitatively investigated in this paper. A selective culture medium with critical NaCl concentration of 4.25% (w/v) was developed firstly and then used to identify and quantify the sublethally injured cells (SICs) from dead and intact cells. Results showed that both the PEF intensity and the total treatment time affected the percent of SICs significantly. About 90% of the cells were sublethally injured when they were exposed to PEF with electric field strength of 5 kV/cm and total treatment time of 1.2 ms, which implied that a lower electric field strength (e.g. 5-10 kV/cm) or a shorter treatment time would produce a great number of SICs. And while under more severe circumstances, more and more microorganisms had been killed. In addition, the biological characteristics and potential value of such sublethally injured cells are also discussed.