| Summary: | 碩士 === 義守大學 === 生物技術與化學工程研究所碩士班 === 99 === Muconic acid, the precursor of Adipic acid, can be used for medicine, agriculture or as a starter of fine chemicals. We screened a local strain, isolated from industrial sewage, which could metabolize benzoic acid into muconic acid. After undergoing mutations and by using the optimally designed medium, the cells have the ability of achieving 65% yield when enough oxygen is supplied. This study, using the fed-batch production of cis,cis-muconic acid by Pesudomonas sp., will discuss: the type of feeding matrix, the matrix concentrations, the operation modes and the feedback inhibition from the system.
There are four kinds of sources on the medium that will affect the activity and productivity: (1)Benzoic acid (B) is the main reaction leading to muconic acid. If the system is applied for a high concentration of benzoic acid, it will inhibit cells activity. To maintain minimal impact on the system, then that should be tried to maintain a low concentration of benzoic acid on the fermentation system. (2)Succinic acid (S) is a supplemental carbon source. If appropriate amount of succinic acid is added to the fermentation, there will be an increase to the metabolic capacity of strain, and a decrease in the product feedback regression. (3) Yeast extract (Y) and (4) Glucose (G) all effectively increase the biomass and improve productivity, but glucose is the best.
Using three sources (G, S, Y) with benzoic acid (B) as different combinations of feeding materials, it was found that BYS is the best substrate compound for the feeding. In the fermenter, when the oxygen is sufficiently supplied for the BYS feeding, the muconic acid reached the maximum output of 19g/L. That product concentration is 2.71 times greater than when only benzoic acid is used for the feeding material and 1.21 times greater than when only BG is used for the feeding material.
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