Background:In acetone-butanol-ethanol(ABE)fermentation by Clostridium acetobutylicum ATCC 824 using corn-based substrate,the solvents are generally produced at a ratio of 3:6:1(A:B:E,w/w).Results:A higher butanol/acet...Background:In acetone-butanol-ethanol(ABE)fermentation by Clostridium acetobutylicum ATCC 824 using corn-based substrate,the solvents are generally produced at a ratio of 3:6:1(A:B:E,w/w).Results:A higher butanol/acetone ratio of 2.9:1 was found when cassava was used as the substrate of an in-situ extractive fermentation by C.acetobutylicum.This ratio had a 64%increment compared to that on corn-based substrate.The metabolic flux and(key enzymes)genes transcriptional analysis indicated that weakened metabolic fluxes in organic acids(especially butyrate)formation and re-assimilation pathways,which associated with lower buk and ctfAB transcriptional levels,contributed to higher butanol and lower acetone production rate in fermentations on cassava.Moreover,NADH generation was enhanced under the enriched reductive environment of using cassava-based substrate,which converted more carbon flux to butanol synthesis pathway,also leading to a higher ratio of butanol/acetone.To further increase butanol/acetone ratio,tiny amount of electron carrier,neutral red was supplemented into cassava-based substrate at 60 h when butonal production rate reached maximal level.However,neutral red addition enhanced NADH production,followed with strengthening the metabolic fluxes of organic acids formation/re-assimilation pathways,resulted in unchanged in butanol/acetone ratio.Conclusions:A further increase in butanol/acetone ratio could be realized when NADH regeneration was enhanced and the metabolic fluxes in organic acids formation/reutilization routes were controlled at suitably low levels simultaneously.展开更多
Acetone-butanol-ethanol(ABE)fermentation is a primary strategy for producing bio-based n-butanol from abundant renewable biomass.In the typical ABE production chain,distillation is an essential unit for high purity AB...Acetone-butanol-ethanol(ABE)fermentation is a primary strategy for producing bio-based n-butanol from abundant renewable biomass.In the typical ABE production chain,distillation is an essential unit for high purity ABE productions,but has long been criticized by the energy-inefficient processes due to the extremely low solvents concentration received in the upstream fermentation system.Over the past decades,efforts have been dedicated to developing eco-efficient ABE distillation processes aimed at reducing both energy costs and capital investments.In this review,a comprehensive overview on ABE distillation systems is provided from physico-chemical properties in feed and thermodynamics to the process constructions and applications.The recent trends in distillation sequence construction that fitting with the rapid developed upstream in situ product recovery(ISPR)systems are emphasized.Furthermore,towards developing a more efficient ABE distillation system,the review takes a broad overview of the intensification strategies for ABE distillation.Along with systematic introduction of the key examples,the future directions for ABE distillation techniques development are also discussed towards a sustainable and low-carbon emission biorefineries.展开更多
Performance of continuous 1-butanol production process by Clostridium bacteria is complicated by alternation of acidogenic and solventogenic phases during fermentation what correlates with culture growth and sporulati...Performance of continuous 1-butanol production process by Clostridium bacteria is complicated by alternation of acidogenic and solventogenic phases during fermentation what correlates with culture growth and sporulation, respectively. However, the strain Clostridium pasteurianum NRRL B598 showed diverse pattern of solvents production when butanol production started during exponential growth phase in batch cultivation. If cultivated under glucose limited conditions with dilution rate 0.03 hl, constant product concentration was almost achieved. By contrast, glucose non-limited continuous experiment operated with dilution rate 0.07 h-1 lead to mutually adverse oscillations of product and glucose concentrations. Regarding the process economy, glucose limited continuous cultivation seems to be superior due to utilization of total supplied glucose amount, advantageous butanol/acetone ratio and higher butanol yield.展开更多
Biobutanol is an advanced biofuel that can be produced from excess lignocellulose via acetone-butanol-ethanol(ABE)fermentation.Although significant technological progress has been made in this field,attempts at larges...Biobutanol is an advanced biofuel that can be produced from excess lignocellulose via acetone-butanol-ethanol(ABE)fermentation.Although significant technological progress has been made in this field,attempts at largescale lignocellulosic ABE production remain scarce.In this study,1m^(3)scale ABE fermentation was investigated using high inhibitor tolerance Clostridium acetobutylicum ABE-P1201 and steam-exploded corn stover hydrolysate(SECSH).Before expanding the fermentation scale,the detoxification process for SECSH was simplified by process engineering.Results revealed that appropriate pH management during the fed-batch cultivation could largely decrease the inhibition of the toxic components in undetoxified SECSH to the solventogenesis phase of the ABE-P1201 strains,avoiding“acid crash”.Therefore,after naturalizing the pH by Ca(OH)_(2),the undetoxified SECSH,without removal of the solid components,reached 17.68±1.30 g/L of ABE production with 0.34±0.01 g/g of yield in 1 L scale bioreactor.Based on this strategy,the fermentation scale gradually expanded from laboratory-scale apparatus to pilot-scale bioreactors.Finally,17.05±1.20 g/L of ABE titer and 0.32±0.01 g/g of ABE yield were realized in 1m3 bioreactor,corresponding to approximately 145 kg of ABE production from 1 t of dry corn stover.The pilot-scale ABE fermentation demonstrated excellent stability during repeated operations.This study provided a simplified ABE fermentation strategy and verified the feasibility of the pilot process,providing tremendous significance and a solid foundation for the future industrialization of second-generation ABE plants.展开更多
two-stage co-culture approach was employed in an acetone-butanol-ethanol(ABE)fermentation.An obligate aerobic bacterium,Arthrobacter sp.,was first grown for 6 h at 30℃ to create anaerobic conditions.Subsequently,Clos...two-stage co-culture approach was employed in an acetone-butanol-ethanol(ABE)fermentation.An obligate aerobic bacterium,Arthrobacter sp.,was first grown for 6 h at 30℃ to create anaerobic conditions.Subsequently,Clostridium beijerinckii TISTR 1461 was inoculated and a fermentation was performed at 37℃.To identify an intermediate temperature suitable for both microorganisms,their growth was examined at 30,34,and 37℃.C.beijerinckii exhibited the highest specific growth rate at 37℃,while Arthrobacter sp.displayed similar growth rates at all tested temperatures.Butanol production from a synthetic medium(P2 medium)by C.beijerinckii at different temperatures using oxygen-free nitrogen(OFN)gas flushing as a control treatment revealed that fermentation at 37℃ gave the highest butanol concentration(PB,9.98 g/L).Consequently,37℃ was chosen for butanol production from sweet sorghum stem juice(SSJ)by co-culture of these two microorganisms in 1-L screw-capped bottles.Compared to the control treatment,higher PB(11.38 g/L),yield(Y_(B/S),0.37 g/g)and productivity(Q_(B),0.24 g/L⋅h)were achieved using the co-culture system.These results were further confirmed by monitoring the oxidation-reduction potential(ORP)during ABE fermentation in a 2-L stirred-tank bioreactor(STR).Moreover,when the co-culture fermentation at 37℃ was scaled up in a 30-L STR,the PB,Y_(B/S)and Q_(B)values were comparable to those obtained in the 2-L STR.Therefore,co-culture fermentation of Arthrobacter sp.and C.beijerinckii TISTR 1461 at 37℃ represents a promising method for large-scale butanol production.展开更多
基金supported by the National Natural Science Foundation Program(#20976072)Major State Basic Research Development Program(#2007CB714303)of China.
文摘Background:In acetone-butanol-ethanol(ABE)fermentation by Clostridium acetobutylicum ATCC 824 using corn-based substrate,the solvents are generally produced at a ratio of 3:6:1(A:B:E,w/w).Results:A higher butanol/acetone ratio of 2.9:1 was found when cassava was used as the substrate of an in-situ extractive fermentation by C.acetobutylicum.This ratio had a 64%increment compared to that on corn-based substrate.The metabolic flux and(key enzymes)genes transcriptional analysis indicated that weakened metabolic fluxes in organic acids(especially butyrate)formation and re-assimilation pathways,which associated with lower buk and ctfAB transcriptional levels,contributed to higher butanol and lower acetone production rate in fermentations on cassava.Moreover,NADH generation was enhanced under the enriched reductive environment of using cassava-based substrate,which converted more carbon flux to butanol synthesis pathway,also leading to a higher ratio of butanol/acetone.To further increase butanol/acetone ratio,tiny amount of electron carrier,neutral red was supplemented into cassava-based substrate at 60 h when butonal production rate reached maximal level.However,neutral red addition enhanced NADH production,followed with strengthening the metabolic fluxes of organic acids formation/re-assimilation pathways,resulted in unchanged in butanol/acetone ratio.Conclusions:A further increase in butanol/acetone ratio could be realized when NADH regeneration was enhanced and the metabolic fluxes in organic acids formation/reutilization routes were controlled at suitably low levels simultaneously.
基金funded by the National Natural Science Foundation of China(22078018)the Natural Science Foundation of Beijing(2222016).
文摘Acetone-butanol-ethanol(ABE)fermentation is a primary strategy for producing bio-based n-butanol from abundant renewable biomass.In the typical ABE production chain,distillation is an essential unit for high purity ABE productions,but has long been criticized by the energy-inefficient processes due to the extremely low solvents concentration received in the upstream fermentation system.Over the past decades,efforts have been dedicated to developing eco-efficient ABE distillation processes aimed at reducing both energy costs and capital investments.In this review,a comprehensive overview on ABE distillation systems is provided from physico-chemical properties in feed and thermodynamics to the process constructions and applications.The recent trends in distillation sequence construction that fitting with the rapid developed upstream in situ product recovery(ISPR)systems are emphasized.Furthermore,towards developing a more efficient ABE distillation system,the review takes a broad overview of the intensification strategies for ABE distillation.Along with systematic introduction of the key examples,the future directions for ABE distillation techniques development are also discussed towards a sustainable and low-carbon emission biorefineries.
文摘Performance of continuous 1-butanol production process by Clostridium bacteria is complicated by alternation of acidogenic and solventogenic phases during fermentation what correlates with culture growth and sporulation, respectively. However, the strain Clostridium pasteurianum NRRL B598 showed diverse pattern of solvents production when butanol production started during exponential growth phase in batch cultivation. If cultivated under glucose limited conditions with dilution rate 0.03 hl, constant product concentration was almost achieved. By contrast, glucose non-limited continuous experiment operated with dilution rate 0.07 h-1 lead to mutually adverse oscillations of product and glucose concentrations. Regarding the process economy, glucose limited continuous cultivation seems to be superior due to utilization of total supplied glucose amount, advantageous butanol/acetone ratio and higher butanol yield.
基金funded by the National Key Research and Development Program of China(grant number:2022YFC2106300).
文摘Biobutanol is an advanced biofuel that can be produced from excess lignocellulose via acetone-butanol-ethanol(ABE)fermentation.Although significant technological progress has been made in this field,attempts at largescale lignocellulosic ABE production remain scarce.In this study,1m^(3)scale ABE fermentation was investigated using high inhibitor tolerance Clostridium acetobutylicum ABE-P1201 and steam-exploded corn stover hydrolysate(SECSH).Before expanding the fermentation scale,the detoxification process for SECSH was simplified by process engineering.Results revealed that appropriate pH management during the fed-batch cultivation could largely decrease the inhibition of the toxic components in undetoxified SECSH to the solventogenesis phase of the ABE-P1201 strains,avoiding“acid crash”.Therefore,after naturalizing the pH by Ca(OH)_(2),the undetoxified SECSH,without removal of the solid components,reached 17.68±1.30 g/L of ABE production with 0.34±0.01 g/g of yield in 1 L scale bioreactor.Based on this strategy,the fermentation scale gradually expanded from laboratory-scale apparatus to pilot-scale bioreactors.Finally,17.05±1.20 g/L of ABE titer and 0.32±0.01 g/g of ABE yield were realized in 1m3 bioreactor,corresponding to approximately 145 kg of ABE production from 1 t of dry corn stover.The pilot-scale ABE fermentation demonstrated excellent stability during repeated operations.This study provided a simplified ABE fermentation strategy and verified the feasibility of the pilot process,providing tremendous significance and a solid foundation for the future industrialization of second-generation ABE plants.
基金supported by the Fundamental Fund 2023 of Khon Kaen Universitysupport from the National Science,Research and Innovation Fund(NSRF),Thailand(Grant.No.179509).
文摘two-stage co-culture approach was employed in an acetone-butanol-ethanol(ABE)fermentation.An obligate aerobic bacterium,Arthrobacter sp.,was first grown for 6 h at 30℃ to create anaerobic conditions.Subsequently,Clostridium beijerinckii TISTR 1461 was inoculated and a fermentation was performed at 37℃.To identify an intermediate temperature suitable for both microorganisms,their growth was examined at 30,34,and 37℃.C.beijerinckii exhibited the highest specific growth rate at 37℃,while Arthrobacter sp.displayed similar growth rates at all tested temperatures.Butanol production from a synthetic medium(P2 medium)by C.beijerinckii at different temperatures using oxygen-free nitrogen(OFN)gas flushing as a control treatment revealed that fermentation at 37℃ gave the highest butanol concentration(PB,9.98 g/L).Consequently,37℃ was chosen for butanol production from sweet sorghum stem juice(SSJ)by co-culture of these two microorganisms in 1-L screw-capped bottles.Compared to the control treatment,higher PB(11.38 g/L),yield(Y_(B/S),0.37 g/g)and productivity(Q_(B),0.24 g/L⋅h)were achieved using the co-culture system.These results were further confirmed by monitoring the oxidation-reduction potential(ORP)during ABE fermentation in a 2-L stirred-tank bioreactor(STR).Moreover,when the co-culture fermentation at 37℃ was scaled up in a 30-L STR,the PB,Y_(B/S)and Q_(B)values were comparable to those obtained in the 2-L STR.Therefore,co-culture fermentation of Arthrobacter sp.and C.beijerinckii TISTR 1461 at 37℃ represents a promising method for large-scale butanol production.
