A rotating disk contactor（RDC）was designed to perform L-lactic acid fermentation with afilamentous fungi,Rhizopus oryzae,which was immobilized on the surfaces of the rotating discs.Thebioreactor was operated using r...A rotating disk contactor（RDC）was designed to perform L-lactic acid fermentation with afilamentous fungi,Rhizopus oryzae,which was immobilized on the surfaces of the rotating discs.Thebioreactor was operated using repeated-batch method as well as continuous feeding method.Ananionic resin,D354,slightly basic in nature and of high selectivity and capacity was chosen for lacticacid separation.A coupled process of L-lactic acid fermentation and ion-exchange separation wasevaluated experimentally.The results indicated that the pH value of the fermentation broth could bemaintained at about 3-3.5 without any addition of alkali.The conversion ratio of glucose to L-lacticacid was about 0.7 g·g<sup>-1</sup> and the fermentation rate reached as high as 62.5 g·h<sup>-1</sup>·m<sup>-2</sup>.展开更多
Repeated-batch and continuous production of L-lactic acid by immobilized Rhizopusoryzae with calcium alginate entrapment method in a three-phase fluidized-bed bioreactor was stud-ied.The operation conditions were opti...Repeated-batch and continuous production of L-lactic acid by immobilized Rhizopusoryzae with calcium alginate entrapment method in a three-phase fluidized-bed bioreactor was stud-ied.The operation conditions were optimized.The productivity based on total reactor volume wasabout 3 times higher than that with free cells in a traditional stirred tank bioreactor.A mathemat-ical model was proposed and the model predictions were in good agreement with the experimentaldat.展开更多
Ionic liquids(ILs)have been widely used in the pretreatment of biomass.However,the effects of residual ILs on the enzymolysis and fermentation of biomass are still unknown.Therefore,a large quantity of water-washing i...Ionic liquids(ILs)have been widely used in the pretreatment of biomass.However,the effects of residual ILs on the enzymolysis and fermentation of biomass are still unknown.Therefore,a large quantity of water-washing is usually followed after biomass pretreatment to eliminate the inhibition of residual ILs on subsequent hydrolysis and fermentation steps.In this work,the effect of choline glycine([Ch][Gly])concentration on the activity of cellulase and Bacillus sp.strain P38 was systematically investigated to explore the impacts of residual ILs on enzymolysis and fermentation.The results confirmed that the activities of them were almost not inhibited in low concentrations(less than 0.5 wt%)of[Ch][Gly].Under optimal pretreatment conditions,the maximum cellulose digestibility was 99.23%.Enzymatic hydrolysate was suitable for L-lactic acid fermentation without appreciable inhibition,and the highest sugar-acid conversion rate of 96.33%was obtained by simplified detoxification.This work provides an economic route to produce fermentable sugar and L-lactic acid,which shows an industrial application prospect in lignocellulosic biorefinery.展开更多
The effect of salinity on sludge alkaline fermentation at low temperature（20°C） was investigated, and a kinetic analysis was performed. Different doses of sodium chloride（Na Cl, 0–25 g/L） were added into the...The effect of salinity on sludge alkaline fermentation at low temperature（20°C） was investigated, and a kinetic analysis was performed. Different doses of sodium chloride（Na Cl, 0–25 g/L） were added into the fermentation system. The batch-mode results showed that the soluble chemical oxygen demand（SCOD） increased with salinity. The hydrolysate（soluble protein, polysaccharide） and the acidification products（short chain fatty acids（SCFAs）, NH＋4–N, and PO_4^（3-）–P） increased with salinity initially, but slightly declined respectively at higher level salinity（20 g/L or 20–25 g/L）. However, the hydrolytic acidification performance increased in the presence of salt compared to that without salt.Furthermore, the results of Haldane inhibition kinetics analysis showed that the salt enhanced the hydrolysis rate of particulate organic matter from sludge particulate and the specific utilization of hydrolysate, and decreased the specific utilization of SCFAs. Pearson correlation coefficient analysis indicated that the importance of polysaccharide on the accumulation of SCFAs was reduced with salt addition, but the importance of protein and NH＋4–N on SCFA accumulation was increased.展开更多
The fermentation process of butanedioic acid by Actinobacillus succinogenes NJ113 with glucose as substrate was studied in batch system.Kinetic models were proposed based on the Levenspiel and Luedeking-Piret equation...The fermentation process of butanedioic acid by Actinobacillus succinogenes NJ113 with glucose as substrate was studied in batch system.Kinetic models were proposed based on the Levenspiel and Luedeking-Piret equations of cell growth,product formation and substrate consumption.With the correlated model parameters,the model could provide reasonable description for the fermentation process at various glucose concentrations.From the kinetic analysis,the microbial growth of Actinobacillus succinogenes NJ113 gradually slowed down with increasing amount of organic acids,and the growth completely ceased when the amount of organic acids exceeded 23.435 g·L-1.Above this critical value,the concentration of biomass declined linearly with the rate of 0.024 h-1 and the productivity of metabolite also decreased as the fermentation proceeded.The models proposed could be used for the development and optimization of butanedioic acid production processes.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘A rotating disk contactor（RDC）was designed to perform L-lactic acid fermentation with afilamentous fungi,Rhizopus oryzae,which was immobilized on the surfaces of the rotating discs.Thebioreactor was operated using repeated-batch method as well as continuous feeding method.Ananionic resin,D354,slightly basic in nature and of high selectivity and capacity was chosen for lacticacid separation.A coupled process of L-lactic acid fermentation and ion-exchange separation wasevaluated experimentally.The results indicated that the pH value of the fermentation broth could bemaintained at about 3-3.5 without any addition of alkali.The conversion ratio of glucose to L-lacticacid was about 0.7 g·g<sup>-1</sup> and the fermentation rate reached as high as 62.5 g·h<sup>-1</sup>·m<sup>-2</sup>.
基金Supported by the National Natural Science Foundation of China.
文摘Repeated-batch and continuous production of L-lactic acid by immobilized Rhizopusoryzae with calcium alginate entrapment method in a three-phase fluidized-bed bioreactor was stud-ied.The operation conditions were optimized.The productivity based on total reactor volume wasabout 3 times higher than that with free cells in a traditional stirred tank bioreactor.A mathemat-ical model was proposed and the model predictions were in good agreement with the experimentaldat.
基金funded by the National Key R&D Program of China(Grant numbers:No.2021YFE0190800,No.2018YFB1501600)the Strategic Priority Research Program of Chinese Academy of Science(No.XDA21060300,No.XDA24030504)+3 种基金National Natural Science Foundation of China(No.21878292,No.21878314)K.C.Wong Education Foundation(No.GJTD-2018-04)the Joint fund of Innovation Academy for Green Manufacture(No.IAGM2020C12,No.IAGM2020C21)Chinese Academy of Sciences President's International Fellowship Initiative(Grant No.122111WGZJTPYJY20180050).
文摘Ionic liquids(ILs)have been widely used in the pretreatment of biomass.However,the effects of residual ILs on the enzymolysis and fermentation of biomass are still unknown.Therefore,a large quantity of water-washing is usually followed after biomass pretreatment to eliminate the inhibition of residual ILs on subsequent hydrolysis and fermentation steps.In this work,the effect of choline glycine([Ch][Gly])concentration on the activity of cellulase and Bacillus sp.strain P38 was systematically investigated to explore the impacts of residual ILs on enzymolysis and fermentation.The results confirmed that the activities of them were almost not inhibited in low concentrations(less than 0.5 wt%)of[Ch][Gly].Under optimal pretreatment conditions,the maximum cellulose digestibility was 99.23%.Enzymatic hydrolysate was suitable for L-lactic acid fermentation without appreciable inhibition,and the highest sugar-acid conversion rate of 96.33%was obtained by simplified detoxification.This work provides an economic route to produce fermentable sugar and L-lactic acid,which shows an industrial application prospect in lignocellulosic biorefinery.
基金supported by the National Natural Science Foundation of China (No. 51178007)
文摘The effect of salinity on sludge alkaline fermentation at low temperature（20°C） was investigated, and a kinetic analysis was performed. Different doses of sodium chloride（Na Cl, 0–25 g/L） were added into the fermentation system. The batch-mode results showed that the soluble chemical oxygen demand（SCOD） increased with salinity. The hydrolysate（soluble protein, polysaccharide） and the acidification products（short chain fatty acids（SCFAs）, NH＋4–N, and PO_4^（3-）–P） increased with salinity initially, but slightly declined respectively at higher level salinity（20 g/L or 20–25 g/L）. However, the hydrolytic acidification performance increased in the presence of salt compared to that without salt.Furthermore, the results of Haldane inhibition kinetics analysis showed that the salt enhanced the hydrolysis rate of particulate organic matter from sludge particulate and the specific utilization of hydrolysate, and decreased the specific utilization of SCFAs. Pearson correlation coefficient analysis indicated that the importance of polysaccharide on the accumulation of SCFAs was reduced with salt addition, but the importance of protein and NH＋4–N on SCFA accumulation was increased.
文摘The fermentation process of butanedioic acid by Actinobacillus succinogenes NJ113 with glucose as substrate was studied in batch system.Kinetic models were proposed based on the Levenspiel and Luedeking-Piret equations of cell growth,product formation and substrate consumption.With the correlated model parameters,the model could provide reasonable description for the fermentation process at various glucose concentrations.From the kinetic analysis,the microbial growth of Actinobacillus succinogenes NJ113 gradually slowed down with increasing amount of organic acids,and the growth completely ceased when the amount of organic acids exceeded 23.435 g·L-1.Above this critical value,the concentration of biomass declined linearly with the rate of 0.024 h-1 and the productivity of metabolite also decreased as the fermentation proceeded.The models proposed could be used for the development and optimization of butanedioic acid production processes.
