| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 90 === The present research used a recombinant strain, Escherichia coli BL21(DE3)/(PET43.1a),to produce interleukin-20 which can be used to treat and study with pso-riasis. With this research we found that the most suitable temperature for the growth of this strain is 42oC, and it can’t grow well in basic condition ,and the DO 20% is enough for the growth of the srtain.37oC is the best temperature for production at the same growth temperature. With the 42oC growth temperature, the highest protein concentration it can reach is 0.42 g/L. When we lower the growth temperature to 37oC,in spite of cell density 14.3 g/L, the target protein concentration can rise to 0.898 g/L. At this study, the protease concentration is higher at 42oC growth temperature than 37oC, and the protease activity is about the same within all the production temperature range. According to the above result, the main reason for the rise of the target protein concentration is the protease concentration. This strain can also be induced with lactose. After batch fermentation, we found that 10 g/L lactose is not enough for this strain to express significant amount of target protein. When we used 20 g/L lactose for induction, 1.135 g/L of our target protein can be produced. And its specific productivity is 0.05 g/g cell, which is a little lower than the value 0.062g/g cell achieved when induced with 1 mM IPTG. It will affect the production of our target protein that this strain can produce inclusion body .
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