The feeding method of propionic acid for production ofpoly(3-hydroxybutyrate-co-3-hydro xyvalerate) [P(3HB-co-3HV)] by fed-batch culture of Ralstoniaeutropha was optimized to achieve high cell density and high 3HV yie...The feeding method of propionic acid for production ofpoly(3-hydroxybutyrate-co-3-hydro xyvalerate) [P(3HB-co-3HV)] by fed-batch culture of Ralstoniaeutropha was optimized to achieve high cell density and high 3HV yield. Effects of different feedingstrategies of propionic acid on the production of P(3HB-co-3HV) were investigated. A decline ofspecific synthesis rate of copolymer and the yield of 3HV unit from propionic acid were observed dueto the propionic acid accumulation in culture broth when the feeding solution with highP/G(propionic acid to glucose) ratio was employed. It was further confirmed by controlling propionicacid concentration at a low level in the separate feeding of propionic acid. An optimal feedingstrategy was demonstrated to reduce the propionic acid accumulation. The cell concentration,P(3HB-co-3HV) productivity and 3HV unit fraction reached to 163.9kg·m^(-3), 1.8kg·m^(-3)·h^(-1),and 10.6%(by mass), respectively, resulting in a yield of 0.33g HV per g propionic acid.展开更多
Ralstonia eutropha was genetically modified to induce ethanol production from glucose. An electrochemical bioreactor was prepared to generate electrochemical reducing power coupled to regeneration of NADH. Growing cel...Ralstonia eutropha was genetically modified to induce ethanol production from glucose. An electrochemical bioreactor was prepared to generate electrochemical reducing power coupled to regeneration of NADH. Growing cells of recombinant R. eutropha produced about 29 mM of ethanol in conventional conditions and 56 mM of ethanol in electrochemically reduced conditions from 100 mM glucose. Grown cells of the recombinant produced about 52 mM of ethanol in conventional conditions and 142 mM of ethanol in electrochemically reduced condition from 100 mM glucose. These results are a clue that electrochemical reducing power can induce the recombinant R. eutropha to produce more ethanol coupled to increase of NADH/NAD+ ratio.展开更多
A new technology was developed to couple the anaerobic digestion of food wastes with production of polyhydroxyalkanoates (PHAs). Acetic, propionic, butyric and lactic acids were produced during food wastes anaerobic d...A new technology was developed to couple the anaerobic digestion of food wastes with production of polyhydroxyalkanoates (PHAs). Acetic, propionic, butyric and lactic acids were produced during food wastes anaerobic digestion and their concentrations reached 5.5, 1.8, 27.4 and 32.7 g/L, respectively under appropriate digestion conditions. The fermentative acids were transferred through a dialysis membrane to an air-lift reactor for PHA synthesis by Ralstonia eutropha. Dry cell concentration and PHA content reached 22.7 g/L and 72.6%, respectively. The obtained PHA was a copolymer of b-hydroxybutyrate (HB) and b-hydroxyvalerate (HV) with 2.8% (mole ratio) of HV units in polymer.展开更多
The decarbonization of the chemical industry and a shift toward circular economies because of high global CO_(2) emissions make CO_(2) an attractive feedstock for manufacturing chemicals.Moreover,H_(2) is a low-cost a...The decarbonization of the chemical industry and a shift toward circular economies because of high global CO_(2) emissions make CO_(2) an attractive feedstock for manufacturing chemicals.Moreover,H_(2) is a low-cost and carbon-free reductant because technologies such as solar-driven electrolysis and supercritical water(scH_(2)O) gasification enable sustainable production of molecular hydrogen(H_(2)).We review the recent advances in engineering Ralsto-nia eutropha,the representative species of“Knallgas”bacteria,for utilizing CO_(2) and H_(2) to autotrophically produce 2,3-butanediol(2,3-BDO).This assessment is focused on state-of-the-art approaches for splitting H_(2) to supply en-ergy in the form of ATP and NADH to power cellular reactions and employing the Calvin-Benson-Bassham cycle for CO_(2) fixation.Major challenges and opportunities for application and future perspectives are discussed in the context of developing other promising CO_(2) and H_(2)-utilizing microorganisms,exemplified by Zymomonas mobilis.展开更多
文摘The feeding method of propionic acid for production ofpoly(3-hydroxybutyrate-co-3-hydro xyvalerate) [P(3HB-co-3HV)] by fed-batch culture of Ralstoniaeutropha was optimized to achieve high cell density and high 3HV yield. Effects of different feedingstrategies of propionic acid on the production of P(3HB-co-3HV) were investigated. A decline ofspecific synthesis rate of copolymer and the yield of 3HV unit from propionic acid were observed dueto the propionic acid accumulation in culture broth when the feeding solution with highP/G(propionic acid to glucose) ratio was employed. It was further confirmed by controlling propionicacid concentration at a low level in the separate feeding of propionic acid. An optimal feedingstrategy was demonstrated to reduce the propionic acid accumulation. The cell concentration,P(3HB-co-3HV) productivity and 3HV unit fraction reached to 163.9kg·m^(-3), 1.8kg·m^(-3)·h^(-1),and 10.6%(by mass), respectively, resulting in a yield of 0.33g HV per g propionic acid.
文摘Ralstonia eutropha was genetically modified to induce ethanol production from glucose. An electrochemical bioreactor was prepared to generate electrochemical reducing power coupled to regeneration of NADH. Growing cells of recombinant R. eutropha produced about 29 mM of ethanol in conventional conditions and 56 mM of ethanol in electrochemically reduced conditions from 100 mM glucose. Grown cells of the recombinant produced about 52 mM of ethanol in conventional conditions and 142 mM of ethanol in electrochemically reduced condition from 100 mM glucose. These results are a clue that electrochemical reducing power can induce the recombinant R. eutropha to produce more ethanol coupled to increase of NADH/NAD+ ratio.
文摘A new technology was developed to couple the anaerobic digestion of food wastes with production of polyhydroxyalkanoates (PHAs). Acetic, propionic, butyric and lactic acids were produced during food wastes anaerobic digestion and their concentrations reached 5.5, 1.8, 27.4 and 32.7 g/L, respectively under appropriate digestion conditions. The fermentative acids were transferred through a dialysis membrane to an air-lift reactor for PHA synthesis by Ralstonia eutropha. Dry cell concentration and PHA content reached 22.7 g/L and 72.6%, respectively. The obtained PHA was a copolymer of b-hydroxybutyrate (HB) and b-hydroxyvalerate (HV) with 2.8% (mole ratio) of HV units in polymer.
基金This work was authored by Alliance for Sustainable Energy,LLC,the Manager and Operator of the National Renewable Energy Laboratory for the U.S.Department of Energy(DOE)under Contract No.DE-AC36-08GO28308Funding provided by U.S.Department of Energy Office of Energy Efficiency and Renewable Energy,Bioenergy Technologies Of-fice(BETO)Funding for YJB was provided by the Center for Bioenergy Innovation(CBI),a U.S.Department of Energy Bioenergy Research Cen-ter supported by the Office of Biological and Environmental Research in the DOE Office of Science.
文摘The decarbonization of the chemical industry and a shift toward circular economies because of high global CO_(2) emissions make CO_(2) an attractive feedstock for manufacturing chemicals.Moreover,H_(2) is a low-cost and carbon-free reductant because technologies such as solar-driven electrolysis and supercritical water(scH_(2)O) gasification enable sustainable production of molecular hydrogen(H_(2)).We review the recent advances in engineering Ralsto-nia eutropha,the representative species of“Knallgas”bacteria,for utilizing CO_(2) and H_(2) to autotrophically produce 2,3-butanediol(2,3-BDO).This assessment is focused on state-of-the-art approaches for splitting H_(2) to supply en-ergy in the form of ATP and NADH to power cellular reactions and employing the Calvin-Benson-Bassham cycle for CO_(2) fixation.Major challenges and opportunities for application and future perspectives are discussed in the context of developing other promising CO_(2) and H_(2)-utilizing microorganisms,exemplified by Zymomonas mobilis.
