Thermosensitivity of a barosensitive Saccharomyces cerevisiae mutant obtained by UV mutagenesis

Abstract

Using UV mutagenesis, a high pressure (HP)-sensitive (barosensitive) mutant of Saccharomyces cerevisiae was obtained. The mutant strain a924E1 showed a significant loss of viability at HP levels of 175 to 250 MPa at 20 °C compared with the parent strain. This strain also showed a significant loss of viability following heat treatment at 50–58 °C at 0.1 MPa. These results showed that the mutation caused a significant thermosensitivity as well as barosensitivity. The activation volume and activation energy values for the inactivation of strain a924E1 were equivalent to those of the parent strain. This suggested that the mechanism for the HP and thermal inactivation reaction of strain a924E1 was basically the same as that of the parent strain. Strain a924E1 showed no deficiency in growth and fermentation ability as well as auxotrophic property. Although the identification of the genetic sites of mutation introduced is underway, these phenotypes are favorable for the application of HP treatment and heat-assisted HP treatment on fermentation control.

Keywords:

• high hydrostatic pressure
• yeast
• UV mutagenesis
• barosensitive
• thermosensitive

Acknowledgements

Part of this work was financially supported by the program Niigata Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence of the Japan Science and Technology Agency. We thank Dr Yoichi Noda (The University of Tokyo) for kindly providing the yeast strain.