D-Glucose, L-arabinose, D-mannose, D-xylose, and cellobiose are saccharification products of lignocellulose and important carbon sources for industrial fermentation. The fermentation efficiency with each of the five s...D-Glucose, L-arabinose, D-mannose, D-xylose, and cellobiose are saccharification products of lignocellulose and important carbon sources for industrial fermentation. The fermentation efficiency with each of the five sugars and the mixture of the two most dominant sugars, D-glucose and D-xylose, was evaluated for acetone- butanol-ethanol （ABE） fermentation by Clostridium acetobutylicum ATCC 824. The utilization efficacy of the five reducing sugars was in the order of D-glucose, L-arabinose, D-mannose, o-xylose and cellobiose, o-Xylose, the second most abundant component in lignocellulosic hydrolysate, was used in the fermentation either as sole carbon source or mixed with glucose. The results indicated that maintaining pH at 4.8, the optimal pH value for solventogenesis, could increase D-xylose consumption when it was the sole carbon source. Different media con- taining D-glucose and D-xylose at different ratios （1：2, 1：5, 1.5：1, 2：1 ） were then attempted for the ABE fermenta- tion. When pH was at 4.8 and xylose concentration was five times that of glucose, a 256.9% increase in xylose utilization and 263.7% increase in solvent production were obtained compared to those without pH control. These results demonstrate a possible approach combining optimized pH control and D-glucose and D-xylose ratio to increase the fermentation efficiency of lignocellulosic hydrolysate.展开更多
Rhamnolipid production by Pseudomonas aeruginosa ATCC 9027 with waste frying oil as sole carbon source was studied using response surface method. Cultures were incubated in shaking flask with temperature, NO3- and Mg2...Rhamnolipid production by Pseudomonas aeruginosa ATCC 9027 with waste frying oil as sole carbon source was studied using response surface method. Cultures were incubated in shaking flask with temperature, NO3- and Mg2+ concentrations as the variables. Meanwhile, fed-batch fermentation experiments were conducted. The results show that the three variables are closely related to rhamnolipid production. The optimal cultivation conditions are of 6.4 g/L NaNO3 , 3.1 g/L MgSO4 at 32 ℃, with the maximum rhamnolipid production of 6.6 g/L. The results of fed-batch fermentation experiments show that feeding the oil in two batches can enhance rhamnolipid production. The best time interval is 72 h with the maximum rhamnolipid production of 8.5 g/L. The data are potentially useful for mass production of rhamnolipid on oil waste with this bacterium.展开更多
Reverse-transcription qualitative PCR(RT-qPCR)was used to analyze the changes in transcription levels of the sulfur metabolism-related periplasmic protein genes of Acidithiobacillus ferrooxidans ATCC 23270 grown on su...Reverse-transcription qualitative PCR(RT-qPCR)was used to analyze the changes in transcription levels of the sulfur metabolism-related periplasmic protein genes of Acidithiobacillus ferrooxidans ATCC 23270 grown on sulfur or ferrous.Seven periplasmic proteins with apparently higher abundance grown on elemental sulfur than on ferrous sulfate were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF-MS).Expression analysis of the corresponding genes by RT-qPCR shows that the constitutive expression of all those genes are more up-regulated grown on sulfur than those grown on ferrous(>10 folder).Study on the corresponding genes of the identified periplasmic proteins by RT-qPCR confirmed the results of two-dimensioned gel electrophoresis,indicating they may be related with sulfur metabolism in A.ferrooxidans.展开更多
基金Supported by the National Natural Science Foundation of China(20306026 and 21376215)the National High Technology Research and Development Program of China(2012AA022302)
文摘D-Glucose, L-arabinose, D-mannose, D-xylose, and cellobiose are saccharification products of lignocellulose and important carbon sources for industrial fermentation. The fermentation efficiency with each of the five sugars and the mixture of the two most dominant sugars, D-glucose and D-xylose, was evaluated for acetone- butanol-ethanol （ABE） fermentation by Clostridium acetobutylicum ATCC 824. The utilization efficacy of the five reducing sugars was in the order of D-glucose, L-arabinose, D-mannose, o-xylose and cellobiose, o-Xylose, the second most abundant component in lignocellulosic hydrolysate, was used in the fermentation either as sole carbon source or mixed with glucose. The results indicated that maintaining pH at 4.8, the optimal pH value for solventogenesis, could increase D-xylose consumption when it was the sole carbon source. Different media con- taining D-glucose and D-xylose at different ratios （1：2, 1：5, 1.5：1, 2：1 ） were then attempted for the ABE fermenta- tion. When pH was at 4.8 and xylose concentration was five times that of glucose, a 256.9% increase in xylose utilization and 263.7% increase in solvent production were obtained compared to those without pH control. These results demonstrate a possible approach combining optimized pH control and D-glucose and D-xylose ratio to increase the fermentation efficiency of lignocellulosic hydrolysate.
基金Project(108100) supported by the Key Program for Science and Technology Research of Ministry of Education of ChinaProjects(50978087, 50908081) supported by the National Natural Science Foundation of China+1 种基金Project(531107011019) supported by the Hunan University Graduate Education Innovation Program, ChinaProject(CX2010B157) supported by the Hunan Provincial Innovation Foundation for Postgraduate students, China
文摘Rhamnolipid production by Pseudomonas aeruginosa ATCC 9027 with waste frying oil as sole carbon source was studied using response surface method. Cultures were incubated in shaking flask with temperature, NO3- and Mg2+ concentrations as the variables. Meanwhile, fed-batch fermentation experiments were conducted. The results show that the three variables are closely related to rhamnolipid production. The optimal cultivation conditions are of 6.4 g/L NaNO3 , 3.1 g/L MgSO4 at 32 ℃, with the maximum rhamnolipid production of 6.6 g/L. The results of fed-batch fermentation experiments show that feeding the oil in two batches can enhance rhamnolipid production. The best time interval is 72 h with the maximum rhamnolipid production of 8.5 g/L. The data are potentially useful for mass production of rhamnolipid on oil waste with this bacterium.
基金Projects(50674101,50974140)supported by the National Natural Science Foundation of ChinaProject(2010CB630902)supported by the National Basic Research Program of China
文摘Reverse-transcription qualitative PCR(RT-qPCR)was used to analyze the changes in transcription levels of the sulfur metabolism-related periplasmic protein genes of Acidithiobacillus ferrooxidans ATCC 23270 grown on sulfur or ferrous.Seven periplasmic proteins with apparently higher abundance grown on elemental sulfur than on ferrous sulfate were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF-MS).Expression analysis of the corresponding genes by RT-qPCR shows that the constitutive expression of all those genes are more up-regulated grown on sulfur than those grown on ferrous(>10 folder).Study on the corresponding genes of the identified periplasmic proteins by RT-qPCR confirmed the results of two-dimensioned gel electrophoresis,indicating they may be related with sulfur metabolism in A.ferrooxidans.
