Construction of Useful Temperature-dependent Gene Expresssion System in S. cerevisiae and It's Application to a Cultivation Process

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The goal of this study are to construct an efficient temperature-sensitive gene expression system in Saccharomyces cerevisiae and to get an optimum solution for maximum production of a useful bio-product using this host-vector system. We got the following results.(1) Utilizing MF_<alpha>1::PHO5 vector, we constructed a temperature-sensitive gene expresssion system and used for acidec phosphatase(APase) production. Optimal strategy was a two-level control of the cultivation temperature which could be interpreted as a two-stage production. This was confirmed experimentally.(2) This gene-expression system was applied to production of a foreign protein, rice alpha-amylase and got a fairly good result.(3) PHO84 promotor was introduced to a host(SH3337-strain) which is PHO81 temperature-sensitive mutant. Using this gene expression system, rice-alpha-amylase was produced more than the former system.(4) For this gene expression system, an optimal strategy of cultivation temperature was also obtained using the relationship between the specific growth rate, specific production rate and cultivation temperature. Optimal strategy was a bang-bang control of temperature such as switching from 30 C to 25 C and it could be also iterpreted as a two-stage production having growth stage and production stage.