Effect of commercial cellulose enzymes was investigated by batch enzymatic hydrolysis at 15.0% （w/v） solid. It was found that the best commercial cellulose enzyme was Cellic（R） CTec comparing to Accellerase 1000TM...Effect of commercial cellulose enzymes was investigated by batch enzymatic hydrolysis at 15.0% （w/v） solid. It was found that the best commercial cellulose enzyme was Cellic（R） CTec comparing to Accellerase 1000TM and Accelerase 1500TM. The Cellic（R） CTec gave the highest reducing sugar concentration and rice straw conversion. Moreover, when the hydrolysate obtained from hydrolysis using Cellic（R） CTec was fermented by Saccharomyces cerevisiae TISTR 5596, it would give the highest ethanol. In this study, the Cellic（R） CTec was used for fed-batch prehydrolysis prior to ethanol production by simultaneous saccharification and fermentation （SSF） way at 20% （w/v） solid loading. It could produce 35.76 g/L or 4.6% （v/v） of ethanol concentration and 83.67 L/ton dry matter （DM） of yield.展开更多
Cellulose biomass is being investigated as a potential substrate for bioethanol production. Cassava stalks were successfully converted to ethanol by fermentation using Saccharomyces cerevisiae TISTR5048, S. cerevisiae...Cellulose biomass is being investigated as a potential substrate for bioethanol production. Cassava stalks were successfully converted to ethanol by fermentation using Saccharomyces cerevisiae TISTR5048, S. cerevisiae KM1195, S. cerevisiae KM7253 and co-culture of S. cerevisiae TISTR5048 and Candida tropicalis TISTR5045. The objective of this study was to assess the ethanol production from cassava stalks by dilute-acid pretreatment and enzymatic hydrolysis that were convertible into ethanol by mono-culture and co-culture of yeast strain. Cassava stalks 1.5% （w/v） in 0.1 M sulfuric acid was pretreated for 30 min at 135 ℃ under the pressure of 15 lb/inch2. The pretreated cassava stalk suspensions were neutralized to pH 5.5 for saccharification process. The enzyme solution （a-amylase, amyloglucosidase, cellulase, xylanase and pectinase solubilized in buffer pH 5.0） was used for hydrolysis ofpretreated cassava stalk at 50 ℃ for 24 h. The hydrolyaste was supplemented with additional nutrients. The culture was incubated at 30 ℃. The pretreatment of the stalk with dilute-acid resulted sugar yield of 0.57 g/g dry matter from enzymatic hydrolysis, which was higher than dilute-alkaline-pretreated and distilled water-pretreated stalk. The sugar hydrolysate was bioconverted to ethanol with separate hydrolysis and fermentation （SHF） and simultaneous saccharification and fermentation （SSF）. The highest ethanol yields of 98.43% and 95.29% were obtained in SHF and SSF, respectively by S. cerevisiae KM1195. The fermentation time of SSF process was 24-32 h shorter than that of the SHF （= 56 h）, but not significantly leading to difference in ethanol production （5.42 g/L-6.22 g/L for SSF; 5.9 g/L-6.23 g/L for SHF）.展开更多
This paper presents an alternative representation of a system of differential equations qualitatively showing the behavior of the biological rhythm of a crayfish during their transition from juvenile to adult stages. ...This paper presents an alternative representation of a system of differential equations qualitatively showing the behavior of the biological rhythm of a crayfish during their transition from juvenile to adult stages. The model focuses on the interaction of four cellular oscillators coupled by diffusion of a hormone, a parameter μ is used to simu- late the quality of communication among the oscillators, in biological terms, it mea- sures developmental maturity of the crayfish. Since some quorum-sensing mechanism is assumed to be responsible for the synchronization of the biological oscillators, it is nat- ural to investigate the possibility that the underlying diffusion process is not standard, i.e. it may be a so-called anomalous diffusion. In this case, it is well understood that diffusion equations with fractional derivatives describe these processes in a more realis- tic way. The alternative formulation of these equations contains fractional operators of Liouville-Caputo and Caputo-Fabrizio type. The numerical simulations of the equations reflect synchronization of ultradian rhythms leading to a circadian rhythm. The classical behavior is recovered when the order of the fractional derivative is V = 1. We discuss possible biological implications.展开更多
文摘Effect of commercial cellulose enzymes was investigated by batch enzymatic hydrolysis at 15.0% （w/v） solid. It was found that the best commercial cellulose enzyme was Cellic（R） CTec comparing to Accellerase 1000TM and Accelerase 1500TM. The Cellic（R） CTec gave the highest reducing sugar concentration and rice straw conversion. Moreover, when the hydrolysate obtained from hydrolysis using Cellic（R） CTec was fermented by Saccharomyces cerevisiae TISTR 5596, it would give the highest ethanol. In this study, the Cellic（R） CTec was used for fed-batch prehydrolysis prior to ethanol production by simultaneous saccharification and fermentation （SSF） way at 20% （w/v） solid loading. It could produce 35.76 g/L or 4.6% （v/v） of ethanol concentration and 83.67 L/ton dry matter （DM） of yield.
文摘Cellulose biomass is being investigated as a potential substrate for bioethanol production. Cassava stalks were successfully converted to ethanol by fermentation using Saccharomyces cerevisiae TISTR5048, S. cerevisiae KM1195, S. cerevisiae KM7253 and co-culture of S. cerevisiae TISTR5048 and Candida tropicalis TISTR5045. The objective of this study was to assess the ethanol production from cassava stalks by dilute-acid pretreatment and enzymatic hydrolysis that were convertible into ethanol by mono-culture and co-culture of yeast strain. Cassava stalks 1.5% （w/v） in 0.1 M sulfuric acid was pretreated for 30 min at 135 ℃ under the pressure of 15 lb/inch2. The pretreated cassava stalk suspensions were neutralized to pH 5.5 for saccharification process. The enzyme solution （a-amylase, amyloglucosidase, cellulase, xylanase and pectinase solubilized in buffer pH 5.0） was used for hydrolysis ofpretreated cassava stalk at 50 ℃ for 24 h. The hydrolyaste was supplemented with additional nutrients. The culture was incubated at 30 ℃. The pretreatment of the stalk with dilute-acid resulted sugar yield of 0.57 g/g dry matter from enzymatic hydrolysis, which was higher than dilute-alkaline-pretreated and distilled water-pretreated stalk. The sugar hydrolysate was bioconverted to ethanol with separate hydrolysis and fermentation （SHF） and simultaneous saccharification and fermentation （SSF）. The highest ethanol yields of 98.43% and 95.29% were obtained in SHF and SSF, respectively by S. cerevisiae KM1195. The fermentation time of SSF process was 24-32 h shorter than that of the SHF （= 56 h）, but not significantly leading to difference in ethanol production （5.42 g/L-6.22 g/L for SSF; 5.9 g/L-6.23 g/L for SHF）.
文摘This paper presents an alternative representation of a system of differential equations qualitatively showing the behavior of the biological rhythm of a crayfish during their transition from juvenile to adult stages. The model focuses on the interaction of four cellular oscillators coupled by diffusion of a hormone, a parameter μ is used to simu- late the quality of communication among the oscillators, in biological terms, it mea- sures developmental maturity of the crayfish. Since some quorum-sensing mechanism is assumed to be responsible for the synchronization of the biological oscillators, it is nat- ural to investigate the possibility that the underlying diffusion process is not standard, i.e. it may be a so-called anomalous diffusion. In this case, it is well understood that diffusion equations with fractional derivatives describe these processes in a more realis- tic way. The alternative formulation of these equations contains fractional operators of Liouville-Caputo and Caputo-Fabrizio type. The numerical simulations of the equations reflect synchronization of ultradian rhythms leading to a circadian rhythm. The classical behavior is recovered when the order of the fractional derivative is V = 1. We discuss possible biological implications.
