Enhancement of the Efficiency of Bioethanol Production by Saccharomyces cerevisiae via Gradually Batch-Wise and Fed-Batch Increasing the Glucose Concentration

Abstract

High initial glucose concentrations may inhibit glucose utilization and decrease ethanol fermentation efficiency. To minimize substrate inhibition, the effects of feeding yeast with different glucose concentrations on the ethanol production by batch and fed-batch cultures in a 5-L fermentor were investigated. When a batch culture system with Saccharomyces cerevisiae was used for ethanol fermentation with glucose concentrations ranging 10-260 g/L, as a result, 0.2-7.0 g/L biomass and 5.1-115.0 g/L ethanol were obtained. However, substrate inhibition was observed with the initial glucose concentrations greater than 200 g/L in the fermentative media. When a fed-batch culture system (an initial glucose concentration of 180 g/L and total glucose concentration of 260 g/L) was performed, the maximum ethanol concentrations and ethanol yield were significantly higher than those of the batch cultures. The cell biomass, maximum ethanol concentration, and ethanol yields for the fed-batch fermentation cultures were 8.3 g/L, 130.1 g/L and 51% (100% of the theoretical value), respectively. The results indicated that high ethanol concentration and ethanol yield could be achieved by the fed-batch cultures with total glucose concentrations up to 260 g/L.

Inline noninvasive Raman monitoring and feedback control of glucose concentration during ethanol fermentation

“…However, there is no example found in the literature for the control of carbon source (sugar, for example, glucose) concentration, which is a critical parameter during yeast fermentation. High glucose concentrations may inhibit glucose utilization and decrease ethanol fermentation efficiency . Nevertheless, with the control of glucose concentration, there is a possibility to minimize substrate inhibition and improve the production of ethanol.…”

Isolation and identification of aroma producing strain with esterification capacity from yellow water

“…Glucose also played an important role on EA synthesis. In alcoholic fermentation, glucose could be converted to pyruvate by glycolysis pathway, and produce ethanol in an anaerobic environment [41]. In this process, glucose not only provides the energy for growth, but also produces the ethanol for EA synthesis.…”

“…However, excess glucose had an inhibitory effect in the yield of EA that might be attributable to unfavorable osmotic pressure (S2(B) Fig). The sluggish growth of microorganisms was often observed at high osmotic pressures, while initial sugar concentration exceeded a certain level [41].…”

Utilization of Biomass Derived from Cyanobacteria-Based Agro-Industrial Wastewater Treatment and Raisin Residue Extract for Bioethanol Production

“…In this experiment, the initial reducing sugar concentration was 258.6 g L −1 , while the final concentrations of ethanol and number of cells recorded were about 111.0 g L −1 and 180 × 10 6 cells mL −1 , respectively. A plethora of research studies deal with the resistance of S. cerevisiae by performing fermentation in high initial sugar concentrations ranging between 120-350 g L −1 [72][73][74]. Bely et al [75] studied fermentation of must with S. cerevisiae in co-culture, having an initial sugar concentration of 360 g L −1 , where the fermentation was completed in 11 days and yielded 0.48 EtOH/sugars (w/w).…”