| Summary: | 碩士 === 義守大學 === 化學工程學系暨生物技術與化學工程研究所 === 105 === S-adenosyl-methionine(SAM), the precursor of methionine, can be used for curing depression, arthritis, liver disorders and other diseases. Our research team bought S. cerevisiae ATCC 7752 from Food Industry Research and Development Institute(Taiwan), which could metabolize methionine into SAM. With the help of ATCC 7752, the SAM content in microorganism can be up to 8.72% by chemical mutation and the optimum fermentation conditions, providing sufficient glucose and methionine. In this study, SAM was produced by fed-batch fermentation to explore the impact of feed type and concentration on this fed-batch system.
There are three kinds of substances in the fermentation broth (glucose, alcohol and methionine) that will affect the production of SAM in microorganism. As the main nutrient for the bacteria, glucose can promote the growth of microorganism and its metabolism of ATP. As alcohol is produced in the process of metabolism of glucose, excessive glucose can cause Crabtree effect, while if there is no sufficient glucose, the microorganism will consume alcohol, which can cause ATP deficiency. SAM is formed by the combination of methionine and ATP, in which excessive methionine will inhibit the growth of microorganism. Hence, adding the appropriate amount of methionine and the excessive amount of glucose can achieve the best production process with the condition that the alcohol in the system will not be consumed.
In the fermenter, the conduction adding glucose 9 g per hours, and adding 1.5 g of methionine when consumed, under using 300 rpm of a reactor to can reach highest SAM 3.6 g/L. Compared with the batch culture, the concentration of SAM increased 6.2 times, while the cellular SAM content has increased by 33.5 %.
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