[Objective]To study the effect of supplies of nitrogen level on spring maize leaf blade carbon metabolism.[Method]In this experiment,field trail and biochemistry analysis were used to study the effect of the diference...[Objective]To study the effect of supplies of nitrogen level on spring maize leaf blade carbon metabolism.[Method]In this experiment,field trail and biochemistry analysis were used to study the effect of the diference-nitrogen level on the content of chlorophyl and carboxylase activity of RuBP and PEP in the leaf of spring maize during main growing period.[Result]Applying proper amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize,insufficient or excessive（N 400 kg/hm^2） of nitrogenous fertilizer has the adverse effect.[Conclusion]In this experiment,applying 300 kg/hm^2 amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize during main growing period.It was important to strengthens the leaf blade photosynthesis ability,promote the yield formation and postpone the decline of leaf blade.展开更多
The nitrogen source requirements for riboflavin production by ccpA mutant Bacillus subtilis 24A1/pMX45 were optimized using linear regression. The optimal medium components considered included 8% glucose as carbon sou...The nitrogen source requirements for riboflavin production by ccpA mutant Bacillus subtilis 24A1/pMX45 were optimized using linear regression. The optimal medium components considered included 8% glucose as carbon source, 2% yeast powder, 0.05% MgSO4 ·7H2O, and four types of nitrogen sources ： 0.1% yeast extract, 2% soybean powder, 1% corn plasm, and 0.2% （ NH4 ） 2 HPO4 in shake flask tests. Predictive ellipsoid was applied to determining the response values under the optimal levels for riboflavin production and glucose consumption. The optimal concentrations of the four types of nitrogen sources can remedy ammonium assimilative defection of ccpA mutant. Under the optimal conditions, the riboflavin yield increases to more than 5.0 g/L and 8%, glucose can be consumed completely after 60 h.展开更多
To achieve higher antibiotic streptolydigin productivity through metabolic regulation, propionate was fed during the fermentation of Streptomyces lydicus AS 4.2501. The effects of propionate feeding on streptolydigin ...To achieve higher antibiotic streptolydigin productivity through metabolic regulation, propionate was fed during the fermentation of Streptomyces lydicus AS 4.2501. The effects of propionate feeding on streptolydigin production and intracellular fluxes were investigated. The highest streptolydigin production yield of 95.10mg·L-1 was obtained when 2mmol·L-1 of sodium propionate was added at 60h of cultivation into shake-flask culture. This yield is 23.06% higher when compared to that of a batch culture without propionate supplementation. It was also found that when propionate was added, much more organic acids were excreted. Metabolic flux analysis was per-formed and it demonstrated that the carbon fluxes of the pentose phosphate pathway and the anaplerotic reaction were significantly increased after propionate feeding. The carbon flux from pyruvate to acetyl-CoA was determined to be 24.7, which was 12.27% higher than that in the batch culture. This study indicated that the glu-cose-6-phosphate and pyruvate nodes were potential bottlenecks for increasing streptolydigin productivity. Potential targets and strategies that could be manipulated through genetic and process engineering to increase the production of streptolydigin were also suggested.展开更多
基金Supported by National Key Technology R & D Program during 11th Five-years Plan(2006BAD02A10)~~
文摘[Objective]To study the effect of supplies of nitrogen level on spring maize leaf blade carbon metabolism.[Method]In this experiment,field trail and biochemistry analysis were used to study the effect of the diference-nitrogen level on the content of chlorophyl and carboxylase activity of RuBP and PEP in the leaf of spring maize during main growing period.[Result]Applying proper amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize,insufficient or excessive（N 400 kg/hm^2） of nitrogenous fertilizer has the adverse effect.[Conclusion]In this experiment,applying 300 kg/hm^2 amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize during main growing period.It was important to strengthens the leaf blade photosynthesis ability,promote the yield formation and postpone the decline of leaf blade.
文摘The nitrogen source requirements for riboflavin production by ccpA mutant Bacillus subtilis 24A1/pMX45 were optimized using linear regression. The optimal medium components considered included 8% glucose as carbon source, 2% yeast powder, 0.05% MgSO4 ·7H2O, and four types of nitrogen sources ： 0.1% yeast extract, 2% soybean powder, 1% corn plasm, and 0.2% （ NH4 ） 2 HPO4 in shake flask tests. Predictive ellipsoid was applied to determining the response values under the optimal levels for riboflavin production and glucose consumption. The optimal concentrations of the four types of nitrogen sources can remedy ammonium assimilative defection of ccpA mutant. Under the optimal conditions, the riboflavin yield increases to more than 5.0 g/L and 8%, glucose can be consumed completely after 60 h.
基金Supported by the National Natural Science Foundation of China (No.20425620)the Program for Changjiang Scholars andInnovative Research Team in University from the Ministry of Education of China.
文摘To achieve higher antibiotic streptolydigin productivity through metabolic regulation, propionate was fed during the fermentation of Streptomyces lydicus AS 4.2501. The effects of propionate feeding on streptolydigin production and intracellular fluxes were investigated. The highest streptolydigin production yield of 95.10mg·L-1 was obtained when 2mmol·L-1 of sodium propionate was added at 60h of cultivation into shake-flask culture. This yield is 23.06% higher when compared to that of a batch culture without propionate supplementation. It was also found that when propionate was added, much more organic acids were excreted. Metabolic flux analysis was per-formed and it demonstrated that the carbon fluxes of the pentose phosphate pathway and the anaplerotic reaction were significantly increased after propionate feeding. The carbon flux from pyruvate to acetyl-CoA was determined to be 24.7, which was 12.27% higher than that in the batch culture. This study indicated that the glu-cose-6-phosphate and pyruvate nodes were potential bottlenecks for increasing streptolydigin productivity. Potential targets and strategies that could be manipulated through genetic and process engineering to increase the production of streptolydigin were also suggested.
