(A) study on the ethanol production by using immobilized Saccharomyces cerevisiae with carrageenan

Abstract

A basic study on the ethanol production with immobilized $\underline{Saccharomyces} \underline{cerevisiae}$ was achieved. K-Carrageenan was used as a matrix and the immobilized gel was treated for hardening with glutarladehyde and hexamethylenediamine. The strain used in packed bed reactor must be able to tolerate anaerobic condition for long time. $\underline{S}. \underline{cerevisiae}$ SC 4126 was more suitable than $\underline{S}. \underline{cerevisiae}$ STV 89 in this respect. To prevent the fermentative activity being lost during immobilization the immobilized gel made using the liquid broth was reincubated in complete medium. The gel reincubated for 60 hr was found that the fermentative activity reached a steady state value, i.e., 2.93g glucose consumption/ml.gel/hour. In the substrate containing only glucose, the activity of the packed bed decreased rapidly. So yeast extract was also fed for the cell growth in the packed gel. The concentration of 4g yeast extract/liter was sufficient to maintain the activity of the packed bed at the residence time of 0.85 hr. Above 149.5g ethanol/liter, the gel in the packed bed could not produce ethanol any more. The productivity ($\pi$) can be calculated from the ethanol concentration in substrate (P), as following equation, $\pi$=26.2 (1-P/149.5). Besides the effect of residence time on the productivity was studied. The relationship of the productivity and residence time is the first function between the residence time of 0.6 hr and 3.5 hr. The superficial velocity is an independent factor on the productivity. Further study is necessary to probe the kinetics and optimization of the packed bed ethanol fermentor.