| 摘要: | 香草醛(Vanillin, 4-Hydroxy-3-methoxybenzaldehyde)，又名香蘭素，其為香草莢氣味的主要來源，香草莢是世界上最受歡迎且使用最廣泛的香料之一，獨特的香氣使得它在許多領域被廣泛應用。目前市場上供應的香草醛主要分為化學合成香草醛和天然香草醛，化學合成香草醛在生產過程中，會對環境產生嚴重汙染，而天然香草醛因昂貴且量少，無法滿足市場需求。因此，近年來開始積極研究利用微生物發酵生產香草醛的方法，以取代化學合成香草醛及滿足消費者對天然香草醛的需求。阿魏酸是生物合成香草醛的理想原料，因其便宜易取得，且在農產廢棄物中含量豐富。利用Amycolatopsis thermoflava轉化阿魏酸生產香草醛，可帶來豐厚商業利益，也可解決農產廢棄物所帶來的環境問題，故兼具了商業應用及環境保護雙重效益。
在微生物發酵過程中，環境溫度會極大地影響微生物的生理狀態及發酵行為，故本論文的目的是探討培養溫度對Amycolatopsis thermoflava轉化阿魏酸生產香草醛的影響。單一溫度實驗結果顯示，在發酵初期培養溫度為45℃可得最大菌重濃度，而培養溫度為35℃可得最大香草醛濃度458 mg/L，相較於培養溫度45℃的操作提升209%。藉由兩階段溫度操作提升香草醛產量，第一階段溫度設定45℃適合菌重增長，然後第二階段調整至35℃以利香草醛生成，在此操作下獲得最大香草醛產量為681 mg/L，相較於單一培養溫度35℃的操作提升49%。透過調控培養溫度可有效提升香草醛之產量，且能更加完善Amycolatopsis thermoflava轉化阿魏酸生產香草醛的研究。;Vanillin (3-methoxy-4-hydroxybenzaldehyde) is one of the major constituents of ‘‘natural vanilla’’ flavor responsible for its characteristic aroma and is the most widely used flavor ingredient in the cosmetics and food industries. The price of ‘‘natural’’ vanillin is very high compared to the chemically synthesized form, mainly due to the limited availability of vanilla pods, which cannot meet the demand of the growing global market for natural vanillin, search for attractive alternative resource is important. Fermentation products are from microorganisms, which are generally considered as natural products. However, only vanillins biotechnologically produced from ferulic acid are considered as food-grade additives by most food safety control authorities worldwide. Furthermore, ferulic acid is rich in agricultural wastes. The microbial fermentation produces high value-added products from inexpensive feedstock such as agricultural wastes, so the cost of production is relatively low, and is more environmental friendly. It is consistent with the concept of sustainable development.
In microbial fermentation procedures, environmental temperature will greatly affect not only the physiological status but also the behavior of fermentation. Ergo, the aim of this study was to investigate the effects of culture temperature on the production of vanillin from ferulic acid by Amycolatopsis thermoflava. The results of experiments showed that the maximum biomass concentration when the culture temperature is 45℃ at the initial stage of fermentation. The optimal vanillin production temperature was 35℃. In this optimal operation, the yield and productivity of vanillin were the highest among other operations, the production of vanillin was 458 mg/L, which was about two hundred and nine percent higher than that obtained from the operation of which culture temperature was fixed at 45℃. Therefore, using the two-stage culture temperature operation, the first stage culture temperature was set at 45℃ to cause more biomass, and then the second stage culture temperature was shifted to 35℃ to enhance the production of vanillin. In this operation, the production of vanillin was 681 mg/L, which was about forty nine percent higher than that obtained from the operation of which culture temperature was fixed at 35℃. As a result, adjusting the culture temperature can make the product formation approaching the ideal type, thereby improving and enhancing the fermentation performance. |
