ABSTRACT
Ethanol production from alkali treated rice straw was investigated by simultaneous saccharification and cofermentation (SSCF) using commercial cellulase and 3 different yeast strains viz., Saccharomyces cerevisiae HAU-1, Pachysolen tannophilus and Candida sp. individually as well as in combination at varied fermentation temperature and incubation time. Dilute alkali (2%) pretreatment of straw resulted in efficient delignification as observed by low residual lignin (12.52%) with 90.6% cellulose and 28.15% hemicellulose recovery. All the 3 yeast strains were able to produce ethanol form alkali treated rice straw and overall ethanol concentration varied from 5.30 to 24.94 g/L based on different fermentation time and temperature. Comparative analysis of ethanol production from different yeast strains combinations revealed maximum ethanol concentration of 23.48 g/L after 96 h incubation at 35ºC with P. tannophilus individually and 24.94 g/L when used as co-culture with Saccharomyces cerevisiae.
ABSTRACT
We investigated a novel process for production of ethanol from glycerol using the yeast Pachysolen tannophilus. After optimization of the fermentation medium, repeated-batch flask culture was performed over a period of 378 hr using yeast cells immobilized on Celite. Our results indicated that the use of Celite for immobilization of P. tannophilus was a practical approach for ethanol production from glycerol, and should be suitable for industrial ethanol production.
Subject(s)
Diatomaceous Earth , Ethanol , Fermentation , Glycerol , Immobilization , YeastsABSTRACT
To optimally convert corn hull, a byproduct from corn processing, into bioethanol using Pachysolen tannophlius, we investigated the optimal conditions for hydrolysis and removal of toxic substances in the hydrolysate via activated carbon treatment as well as the effects of this detoxification process on the kinetic parameters of bioethanol production. Maximum monosaccharide concentrations were obtained in hydrolysates in which 20 g of corn hull was hydrolyzed in 4% (v/v) H2SO4. Activated carbon treatment removed 92.3% of phenolic compounds from the hydrolysate. When untreated hydrolysate was used, the monosaccharides were not completely consumed, even at 480 h of culture. When activated carbon-treated hydrolysate was used, the monosaccharides were mostly consumed at 192 h of culture. In particular, when activated carbon-treated hydrolysate was used, bioethanol productivity (P) and specific bioethanol production rate (Qp) were 2.4 times and 3.4 times greater, respectively, compared to untreated hydrolysate. This was due to sustained bioethanol production during the period of xylose/arabinose utilization, which occurred only when activated carbon-treated hydrolysate was used.