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고정화 효모를 이용한 에탄올 추출발효에서 최적 pH 및 온도에 대한 연구

Study of the Optimum pH and Temperature in Extractive Fermentation using Ca-alginate Entrapped S. cerevisiae

이진석 안필용 홍석인

Lee JS Ahn PY Hong SI

HWAHAK KONGHAK, December 1990, 28(6), 676-683(8), NONE

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Abstract

Ca-alginate에 고정화한 Saccharomyces cerevisiae를 이용한 에탄올의 추출발효에서 최적 pH와 온도에 대해 검토하였다. 혼합용매（TBP : oleic acid=3 : 2）를 사용하여 추출발효했을 때의 최적 pH와 온도는 pH 5.8과 25℃로서 자유효모를 이용한 발효의 최적 pH와 온도인 pH 4.5 및 30℃와 상당한 차이가 있었다[1]. 이 차이는 pH 5.8, 25℃에서 고정화 효모의 pH와 온도에 대한 안정성때문에 효모의 활성도가 거의 저하되지 않은 반면 용매 추출능력의 증가로 에탄올에 의한 반응 억제효과가 줄었기 때문으로 해석된다. 온도가 25℃이고, pH 5.8의 조건에서 400 g/l 포도당 용액 추출발효시 얻은 에탄올 생산성은 1.9 g/l-hr이었고, 최대 에탄올 농도는 180 g/l로서 온도가 30℃이고, pH 4.5의 발효조건에서 얻은 1.6 g/l-hr와 110 g/l에 비해 생산성은 20% 증가되었고, 최대 에탄올 농도는 60% 이상 높았다. 이런 최적 온도와 pH의 이동은 고정화 균체를 이용하여 수행되는 모든 생성물 억제형(product inhibition type)의 추출발효에서도 고려되어야 한다고 생각된다.

Optimum pH and temperature were determined in an extractive fermentation system using Ca-alginate entrapped Saccharomyces cerevisiae. The highest ethanol concentration and productivity of the extractive fermenta-tion system were observed at pH5.8 and 25℃. Meanwhile, the optimum pH and temperature of a fermentation system usingS.cerevisiae were determined to be pH4.5 and 30℃. The reason for this shift is that a product inhibition effect is less due to the improved extraction capacity of the solvent at new optimum pH and temperature and the immobilized cells have relatively constant activity over the pH and temperature range. Extractive fermentation at new pH and tem-perature present higher productivity and maximum ethanol concentration, 1.9g/l-hr and 180g/l, respectively than their counterparts, 1.6g/l-hr and 110g/l, at pH4.5 and 30℃. Shift of new optimum pH and temperature is possible for any extractive fermentation by using immobilized cells in which product inhibition is significant.

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