Simultaneous Ethanol Fermentation Research Articles

Kluyveromyces marxianus-based platform for direct ethanol fermentation and recovery from cellulosic materials under air-ventilated conditions

Consolidated bioprocessing represents an attractive approach to converting cellulosic materials into bioethanol, yet is practically unavailable. We developed a ventilation-mediated, simultaneous ethanol fermentation and recovery system. Running the system under air-supplied conditions, apparently pure ethanol (28g) was recovered from cellobiose (100g) by growing recombinant Kluyveromyces marxianus expressing β-glucosidase.

A kinetic model and simulation of starch saccharification and simultaneous ethanol fermentation by amyloglucosidase and Zymomonas mobilis

A mathematical model is described for the simultaneous saccharification and ethanol fermentation (SSF) of sago starch using amyloglucosidase (AMG) and Zymomonas mobilis. By introducing the degree of polymerization (DP) of oligosaccharides produced from sago starch treated with α-amylase, a series of Michaelis-Menten equations were obtained. After determining kinetic parameters from the results of simple experiments carried out at various substrate and enzyme concentrations and from the subsite mapping theory, this model was adapted to simulate the SSF process. The results of simulation for SSF are in good agreement with experimental results.

Simultaneous ethanol fermentation and stripping process coupled with rectification

Ethanol stripping characteristics of bubble columns to eliminate product inhibition were studied for the improvement of the productivity of the fermentation process. Stripping ethanol vapor was concentrated by the rectifying column packed with coconut shell charcoal (CSC). The stripping rate of ethanol was strongly dependent on the flow rate of the CO 2 gas supplied and temperature. The ethanol stripping rate values agreed fairly well with those of the theoretical equation derived by assuming that no diffusional resistances in gas and liquid films govern the ethanol transfer rate. In the rectifying column with reflux, the condensate ethanol concentration decreased slightly from 740 to 700 g/ l, when the gas flow rate was increased from 0.5 to 6 l/min for the 100 g/ l feed ethanol concentration used for the continuous stripping. With the use of simultaneous fermentation and a stripping process, an improvement of 27% in productivity was obtained from 292 g/ l glucose feed using flocculating yeast recycled from a settler and 4 l/min of CO 2 gas recirculation.

Sago starch saccharification and simultaneous ethanol fermentation by amyloglucosidase and Zymomonas mobilis

AbstractSimultaneous saccharification and ethanol fermentation (SSF) of sago starch was studied using amyloglucosidase (AMG) and Zymomonas mobilis. The optimal concentration of AMG and operating temperature for the SSF process were found to be 0.5% (v/w) and 35°C, respectively. Under these conditions with 150 g dm−3 sago starch as a substrate, the final ethanol concentration obtained was 69.2 g dm−3 and ethanol yield, YP/S, 0.50 g g−1 (97% of theoretical yield). Sago starch in the concentration range of 100–200 g dm−3 was efficiently converted into ethanol. When compared to a two‐step process involving separate saccharification and fermentation stages, the SSF reduced the total process time by half.