[Objective] This study was to realize high-density culture of Chlorella sp. as well as the culture with high lipid yield. [Method] Through analyzing the growth curve of Chlorella sp. cells, dextrose consumption curve,...[Objective] This study was to realize high-density culture of Chlorella sp. as well as the culture with high lipid yield. [Method] Through analyzing the growth curve of Chlorella sp. cells, dextrose consumption curve, change curves of pH and dissolved oxygen, a fed-batch culture was conducted, followed by a nitrogen-deficient culture aiming at accumulating the lipids in Chlorella sp. cells when a high density of Chlorella sp. cells was obtained. [Result] After four batches of feeding were pro- vided, the biomass of Chlorella sp. reached up to 65.25 g/L, and the lipid content increased from 42.75% to 63.82% in Chlorella sp. cells, with the yield of 43.37 g/L in the following 12 hours of nitrogen-deficient culture. [Conclusion] Reasonable fed- batch can significantly improve the biomass of Chlorella sp., and the nitrogen-defi- cient culture further raises the lipid yield of Chlorella sp.展开更多
An acetate-tolerant mutant of Escherichia coli DH5α, DA19, was used for secretory production of human epidermal growth factor （hEGF） whose expression was under the control of phoA promoter. The recombinant cells we...An acetate-tolerant mutant of Escherichia coli DH5α, DA19, was used for secretory production of human epidermal growth factor （hEGF） whose expression was under the control of phoA promoter. The recombinant cells were cultured in a chemically defined medium, and glucose was added at different specific provision rates during the growth and expression phases. It was found that pH had a significant effect on the extracellular hEGF production. The extracellular hEGF concentration was 75.5mg·L^-1, 5.2-fold of the level reached at pH 7.0, even though more acetate was produced. Nitrogen source was limited in the later growth phase. Supplementation of ammonium promoted the consumption of phosphate and reduced the time to exhaust phosphate, but the extracellular hEGF production was similar to that without supplementation of ammonium.展开更多
This paper considers the fed-batch culture in microbial fermentation process, which consists of batch and continuous culture. The goal is to explore the properties of a novel model which can describe the characteristi...This paper considers the fed-batch culture in microbial fermentation process, which consists of batch and continuous culture. The goal is to explore the properties of a novel model which can describe the characteristics of multistage for the population growth of microorganisms in nonlinear switch dynamic system. The improved model is developed based on the experimental data to describe the delayed, developmental and stationary stages well for the phases of batch culture. Then the existence, uniqueness and boundedness of solutions to the nonlinear multistage switch system and the Lipschitz continuity and differentiability of solutions with respect to the initial state is discussed as well. Finally, a numerical simulation is employed for the nonlinear multistage switch system.展开更多
文摘[Objective] This study was to realize high-density culture of Chlorella sp. as well as the culture with high lipid yield. [Method] Through analyzing the growth curve of Chlorella sp. cells, dextrose consumption curve, change curves of pH and dissolved oxygen, a fed-batch culture was conducted, followed by a nitrogen-deficient culture aiming at accumulating the lipids in Chlorella sp. cells when a high density of Chlorella sp. cells was obtained. [Result] After four batches of feeding were pro- vided, the biomass of Chlorella sp. reached up to 65.25 g/L, and the lipid content increased from 42.75% to 63.82% in Chlorella sp. cells, with the yield of 43.37 g/L in the following 12 hours of nitrogen-deficient culture. [Conclusion] Reasonable fed- batch can significantly improve the biomass of Chlorella sp., and the nitrogen-defi- cient culture further raises the lipid yield of Chlorella sp.
基金the National High Technology Research and Development Program of China(863 Program,2002AA217021).
文摘An acetate-tolerant mutant of Escherichia coli DH5α, DA19, was used for secretory production of human epidermal growth factor （hEGF） whose expression was under the control of phoA promoter. The recombinant cells were cultured in a chemically defined medium, and glucose was added at different specific provision rates during the growth and expression phases. It was found that pH had a significant effect on the extracellular hEGF production. The extracellular hEGF concentration was 75.5mg·L^-1, 5.2-fold of the level reached at pH 7.0, even though more acetate was produced. Nitrogen source was limited in the later growth phase. Supplementation of ammonium promoted the consumption of phosphate and reduced the time to exhaust phosphate, but the extracellular hEGF production was similar to that without supplementation of ammonium.
基金supported by the National Natural Science Foundation of China under Grant Nos.11171050,11101262 and 11371164the National Natural Science Foundation for the Youth of China under Grant Nos.11301081,11401073
文摘This paper considers the fed-batch culture in microbial fermentation process, which consists of batch and continuous culture. The goal is to explore the properties of a novel model which can describe the characteristics of multistage for the population growth of microorganisms in nonlinear switch dynamic system. The improved model is developed based on the experimental data to describe the delayed, developmental and stationary stages well for the phases of batch culture. Then the existence, uniqueness and boundedness of solutions to the nonlinear multistage switch system and the Lipschitz continuity and differentiability of solutions with respect to the initial state is discussed as well. Finally, a numerical simulation is employed for the nonlinear multistage switch system.
