The immobilized yeast always demonstrated faster sugar assimilation and higher final ethanol concentration than the free yeast. Under acetic acid stress, the fixed yeast exhibited less change in unsaturated degree of fatty acids in cellular membrane than the free yeast. Application of immobilized yeast was therefore potential for improvement in ethanol fermentation from lignocellulosic material. | SCIENCE & TECHNOLOGY DEVELOPMENT, Vol 19, 2016 Effect of acetic acid on fermentation performance of the immobilized yeast Kluyveromyces marxianus on Nypa fruticans leaf sheath pieces Vu Thi Le Quyen Le Van Viet Man Ho Chi Minh city University of Technology, VNU-HCM. (Manuscript Received on July, 2016, Manuscript Revised on September, 2016) ABSTRACT The yeast cells of Kluyveromyces marxianus immobilized on Nypa fruticans leaf sheath immobilized and free yeast by to times, respectively. The immobilized yeast always pieces was tested for acetic acid tolerance demonstrated faster sugar assimilation and during ethanol fermentation. Control sample with the free yeast cells were also performed higher final ethanol concentration than the free yeast. Under acetic acid stress, the fixed yeast under the same conditions. When the acetic acid content in the medium varied from 0 to 8g/L, the exhibited less change in unsaturated degree of fatty acids in cellular membrane than the free cell growth rate of the immobilized and free yeast decreased by to time, respectively. yeast. Application of immobilized yeast was therefore potential for improvement in ethanol In addition, increase in acetic acid content from fermentation from lignocellulosic material. 0 to 8g/L reduced ethanol formation rate of the Keywords: acetic acid, bioethanol, Kluyveromycesmarxianus, Nypafruiticans. 1. INTRODUCTION Lignocellulosic biomass such as wood, improved. There have been many pretreatment grass and agriculture residue have been reported as an attractive material for bioethanol methods, among which weak acidic hydrolysis has been widely used because of low cost and production due to their abundance in nature and high efficiency for lignin and hemicellulose low cost [1, 2]. In the production of bioethanol, pretreatment of lignocellulosic biomass is removal [3, 4]. However, diluted acid pretreatment generates toxic compounds, such essential since .
