Leakage of Cellular Materials from Saccharomyces cerevisiae by Ohmic Heating

• Published in: Journal of microbiology and biotechnology Vol. 12; no. 2; pp. 183 - 188
• Main Authors: Sung Won Yoon, Chung Yung J. Lee, Ki Myung Kim, Cherl Ho Lee
• Format: Journal Article
• Language: Korean
• Published: 한국미생물생명공학회 30-04-2002
• Subjects: cell wall; electroporation; Ohmic heating; permeability; Saccharomyces cerevisiae
• ISSN: 1017-7825

The ohmic heating of foods for sterilization provides a shorter come-up time compared to conventional thermal processes. The electric fields as well as the heat generated by ohmic heating facilitate germicidal effects. In the present study, the effect of ohmic heating on the structure and permeability of the cell membrane of yeast cells, Saccharomyces cerevisae, isolated from Takju (a traditional Korean rice-beer), was investigated. The ohmic heating was found to translocate intracellular protein materials out of the cell wall, and the amount of exuded protein increased significantly as the electric field increased from 10 to 20 V/cm. As higher frequencies were applied, more materials were exuded. Compared to conventional heating, more amounts of proteins and nucleic acids were exuded when these cells were treated with ohmic heating. The molecular weights of the major exuded proteins ranged from 4 kDa to 18 kDa, as analyzed by Tricine-SDS PAGE. A TEM study also confirmed the leakage of cellular materials, thus indicating irreversible damage to the cell wall by ohmic heating. It was, therefore, concluded that the electric fields generated by ohmic heating induced electroporation, causing irreversible damage to the yeast cell wall and promoting the translocation of intracellular materials.