[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
A freshwater green microalgae Chlorella sp., UMACC344 was shown to produce high lipid content and has the potential to be used as feedstock for biofuel production. In this study, photosynthetic effciency, biochemical ...A freshwater green microalgae Chlorella sp., UMACC344 was shown to produce high lipid content and has the potential to be used as feedstock for biofuel production. In this study, photosynthetic effciency, biochemical pro?les and non-targeted metabolic pro?ling were studied to compare between the nitrogen-replete and deplete conditions. Slowed growth, change in photosynthetic pigments and lowered photosynthetic effciency were observed in response to nitrogen deprivation. Biochemical pro?les of the cultures showed an increased level of carbohydrate, lipids and total fatty acids, while the total soluble protein content was lowered. A trend of fatty acid saturation was observed in the nitrogen-deplete culture with an increase in the level of saturated fatty acids especially C16:0 and C18:0, accompanied by a decrease in proportions of monounsaturated and polyunsaturated fatty acids. Fifty-nine metabolites, including amino acids, lipids, phytochemical compounds, vitamins and cofactors were signi?cantly dysregulated and annotated in this study. Pathway mapping analysis revealed a rewiring of metabolic pathways in the cells, particularly purine, carotenoid, nicotinate and nicotinamide, and amino acid metabolisms. Within the treatment period of nitrogen deprivation, the key processes involved were reshu ? ing of nitrogen from proteins and photosynthetic machinery, together with carbon repartitioning in carbohydrates and lipids.展开更多
A stable transformation system for the expression of foreign genes in the unicellular green marine alga （Chlorella sp. MACC/C95）was established. Using electroporation, the alga was transformed with a plasmid contain...A stable transformation system for the expression of foreign genes in the unicellular green marine alga （Chlorella sp. MACC/C95）was established. Using electroporation, the alga was transformed with a plasmid containing the phytase gene under the control of CaMV35S promoter and the neomycin phosphotransferase （ npt ） as a selectable marker gene. The integration of the phytase gene into the Chlorella genome was revealed by PCR and Southern blotting analysis. RT-PCR analysis revealed the expression of phytase gene at the transcript level. The enhanced activity of phytase enzyme in the transformants confirmed the integration and successful expression of phytase gene. The introduced phytase gene and its protein expression were stably maintained for at least 30 generations in media devoid of selectable antibiotics G418. This is an important step toward the production of useful foreign proteins in Chlorella sp. MACC/C95.展开更多
SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0, whereby sulfite is yielded from the disassociation of protons. We aimed to improve the sulfite transformation efficiency and prov...SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0, whereby sulfite is yielded from the disassociation of protons. We aimed to improve the sulfite transformation efficiency and provide a basis for the direct utilization of SO2 from flue gas by a microalgal suspension. Chlorella sp. XQ-20044 was cultured in a medium with 20 mmol/L sodium sulfite under different physicochemical conditions. Under light conditions, sulfite concentration in the algal suspension reduced linearly over time, and was completely converted into sulfate within 8 h. The highest sulfite transformation rate （3.25 mmol/ （L.h）） was obtained under the following conditions： 35℃, light intensity of 300 μmol/（m^2·s）, NaHCO3 concentration of 6 g/L, initial cell density （OD540） of 0.8 and pH of 9-10. There was a positive correlation between sulfite transformation rate and the growth of Chlorella, with the conditions favorable to algal growth giving better sulfite transformation. Although oxygen in the air plays a role in the transformation of SO3^2- to SO^2-, the transformation is mainly dependent on the metabolic activity of algal cells. Chlorella sp. XQ-20044 is capable of tolerating high sulfite concentration, and can utilize sulfite as the sole sulfur source for maintaining healthy growth. We found that sulfite 〈20 mmol/L had no obvious effect on the total lipid content and fatty acid profiles of the algae, Thus, the results suggest it is feasible to use flue gas for the mass production of feedstock for biodiesel using Chlorella sp. XQ-20044, without preliminary removal of SO2, assuming there is adequate control of the pH.展开更多
Many strains of microalgae can grow in wastewaters through their ability to utilize inorganic nitrogen and phosphorus in wastewater. The content of municipal wastewater changes from a location to others. Biofuel produ...Many strains of microalgae can grow in wastewaters through their ability to utilize inorganic nitrogen and phosphorus in wastewater. The content of municipal wastewater changes from a location to others. Biofuel production from municipal wastewater has gained huge importance due to progresses in cultivation of microalgae in wastewaters. Biobutanol is produced by the acetone-butanol-ethanol (ABE) fermentation. In this study, we examined the biobutanol production efficiency of Chlorella sp. DEE006 which is cultivated in the municipal wastewater in flat-photobioreactor. Growth of microalgae was monitored at 680 nm using spectrophotometer and the biomass was also pre-treated with acidic hydrolysis (1 M H2SO4). Total carbohydrate and protein contents were measured. Fermented microalgae samples were taken for calculation of biobutanol concentration. We obtained both high biobutanol content (6.23 ± 0.19 g·L−1) and high bioethanol yield 0.16 ± 0.005 g (g sugar)−1. 50% wastewater had the highest biomass concentration (1930 ± 11 mg/L) among the wastewaters with five various concentrations. It had the highest biomass productivity with 0.28 ± 0.001 g L−1d−1. Also, it obtained the highest carbohydrate and protein concentration with 0.80 ± 0.02 gL−1 and 0.95 ± 0.01 gL−1, respectively. According to our results, Chlorella sp. DEE006 can be used for large scale biobutanol production in the future.展开更多
In recent years, the ability of microorganisms to decolorize textile wastewater has received great attention due to the environmental persistence and toxicity of these pollutants. In this paper biological decolorizati...In recent years, the ability of microorganisms to decolorize textile wastewater has received great attention due to the environmental persistence and toxicity of these pollutants. In this paper biological decolorization of triphenylmethane dye, C.I. Basic Green 4 (BG 4), by Chlorella species was investigated. The effect of operational parameters (temperature, pH, initial dye concentration and algal concentration) on decolorization efficiency was examined. Results indicated that the desired initial pH was 9. The stability and efficiency of the algae in long-term repetitive operations were also examined. Michaelis–Menten kinetics was employed to describe the apparent correlation between the decolorization rate and dye concentration. The optimal kinetic parameters, νmax (specific decolorization rate) and Km (maximum specific decolorization rate) were 4.6 mg dye g cell-1 h-1 and 151.0 mg L-1, respectively.展开更多
The function of exogenous alanine(Ala)in regulating biomass accumulation,lipid production,photosynthesis,and respiration in Chlorella pyrenoidosa was studied.Result shows that the supplementation of Ala increased C.py...The function of exogenous alanine(Ala)in regulating biomass accumulation,lipid production,photosynthesis,and respiration in Chlorella pyrenoidosa was studied.Result shows that the supplementation of Ala increased C.pyrenoidosa biomass and lipid production in an 8-d batch culture.The concentration of 10 mmol/L of Ala was optimum and increased the microalgal cell biomass and lipid content by 39.3%and 21.4%,respectively,compared with that in the control(0-mmol/L Ala).Ala supplementation reduced photosynthetic activity while boosting respiratory activity and pyruvate levels,indicating that C.pyrenoidosa used exogenous Ala for biomass accumulation through the respiratory metabolic process.The accelerated respiratory metabolism due to Ala supplementation elevated the substrate pool and improved the lipogenic gene expression,promoting lipid production at last.This study provided a novel method for increasing biomass accumulation and lipid production and elucidated the role of Ala in regulating lipid production.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Supported by the Aerospace Malaysia Innovation Centre&Airbus Group Innovation(No.PV001-2013)the Ministry of Higher Education Malaysia HICoE grant(No.IOES-2014H)+1 种基金the Fundamental Research Grant Scheme(No.FP048-2016)the University of Malaya UMCoE RU Grant(No.RU009H-2015)
文摘A freshwater green microalgae Chlorella sp., UMACC344 was shown to produce high lipid content and has the potential to be used as feedstock for biofuel production. In this study, photosynthetic effciency, biochemical pro?les and non-targeted metabolic pro?ling were studied to compare between the nitrogen-replete and deplete conditions. Slowed growth, change in photosynthetic pigments and lowered photosynthetic effciency were observed in response to nitrogen deprivation. Biochemical pro?les of the cultures showed an increased level of carbohydrate, lipids and total fatty acids, while the total soluble protein content was lowered. A trend of fatty acid saturation was observed in the nitrogen-deplete culture with an increase in the level of saturated fatty acids especially C16:0 and C18:0, accompanied by a decrease in proportions of monounsaturated and polyunsaturated fatty acids. Fifty-nine metabolites, including amino acids, lipids, phytochemical compounds, vitamins and cofactors were signi?cantly dysregulated and annotated in this study. Pathway mapping analysis revealed a rewiring of metabolic pathways in the cells, particularly purine, carotenoid, nicotinate and nicotinamide, and amino acid metabolisms. Within the treatment period of nitrogen deprivation, the key processes involved were reshu ? ing of nitrogen from proteins and photosynthetic machinery, together with carbon repartitioning in carbohydrates and lipids.
文摘A stable transformation system for the expression of foreign genes in the unicellular green marine alga （Chlorella sp. MACC/C95）was established. Using electroporation, the alga was transformed with a plasmid containing the phytase gene under the control of CaMV35S promoter and the neomycin phosphotransferase （ npt ） as a selectable marker gene. The integration of the phytase gene into the Chlorella genome was revealed by PCR and Southern blotting analysis. RT-PCR analysis revealed the expression of phytase gene at the transcript level. The enhanced activity of phytase enzyme in the transformants confirmed the integration and successful expression of phytase gene. The introduced phytase gene and its protein expression were stably maintained for at least 30 generations in media devoid of selectable antibiotics G418. This is an important step toward the production of useful foreign proteins in Chlorella sp. MACC/C95.
基金Supported by the National Natural Science Foundation of China(No.CNSF31272680)the National High Technology Research and Development Program of China(No.2013AA065805)
文摘SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0, whereby sulfite is yielded from the disassociation of protons. We aimed to improve the sulfite transformation efficiency and provide a basis for the direct utilization of SO2 from flue gas by a microalgal suspension. Chlorella sp. XQ-20044 was cultured in a medium with 20 mmol/L sodium sulfite under different physicochemical conditions. Under light conditions, sulfite concentration in the algal suspension reduced linearly over time, and was completely converted into sulfate within 8 h. The highest sulfite transformation rate （3.25 mmol/ （L.h）） was obtained under the following conditions： 35℃, light intensity of 300 μmol/（m^2·s）, NaHCO3 concentration of 6 g/L, initial cell density （OD540） of 0.8 and pH of 9-10. There was a positive correlation between sulfite transformation rate and the growth of Chlorella, with the conditions favorable to algal growth giving better sulfite transformation. Although oxygen in the air plays a role in the transformation of SO3^2- to SO^2-, the transformation is mainly dependent on the metabolic activity of algal cells. Chlorella sp. XQ-20044 is capable of tolerating high sulfite concentration, and can utilize sulfite as the sole sulfur source for maintaining healthy growth. We found that sulfite 〈20 mmol/L had no obvious effect on the total lipid content and fatty acid profiles of the algae, Thus, the results suggest it is feasible to use flue gas for the mass production of feedstock for biodiesel using Chlorella sp. XQ-20044, without preliminary removal of SO2, assuming there is adequate control of the pH.
文摘Many strains of microalgae can grow in wastewaters through their ability to utilize inorganic nitrogen and phosphorus in wastewater. The content of municipal wastewater changes from a location to others. Biofuel production from municipal wastewater has gained huge importance due to progresses in cultivation of microalgae in wastewaters. Biobutanol is produced by the acetone-butanol-ethanol (ABE) fermentation. In this study, we examined the biobutanol production efficiency of Chlorella sp. DEE006 which is cultivated in the municipal wastewater in flat-photobioreactor. Growth of microalgae was monitored at 680 nm using spectrophotometer and the biomass was also pre-treated with acidic hydrolysis (1 M H2SO4). Total carbohydrate and protein contents were measured. Fermented microalgae samples were taken for calculation of biobutanol concentration. We obtained both high biobutanol content (6.23 ± 0.19 g·L−1) and high bioethanol yield 0.16 ± 0.005 g (g sugar)−1. 50% wastewater had the highest biomass concentration (1930 ± 11 mg/L) among the wastewaters with five various concentrations. It had the highest biomass productivity with 0.28 ± 0.001 g L−1d−1. Also, it obtained the highest carbohydrate and protein concentration with 0.80 ± 0.02 gL−1 and 0.95 ± 0.01 gL−1, respectively. According to our results, Chlorella sp. DEE006 can be used for large scale biobutanol production in the future.
基金Financially supported by the University of Tabriz, Iran
文摘In recent years, the ability of microorganisms to decolorize textile wastewater has received great attention due to the environmental persistence and toxicity of these pollutants. In this paper biological decolorization of triphenylmethane dye, C.I. Basic Green 4 (BG 4), by Chlorella species was investigated. The effect of operational parameters (temperature, pH, initial dye concentration and algal concentration) on decolorization efficiency was examined. Results indicated that the desired initial pH was 9. The stability and efficiency of the algae in long-term repetitive operations were also examined. Michaelis–Menten kinetics was employed to describe the apparent correlation between the decolorization rate and dye concentration. The optimal kinetic parameters, νmax (specific decolorization rate) and Km (maximum specific decolorization rate) were 4.6 mg dye g cell-1 h-1 and 151.0 mg L-1, respectively.
基金Supported by the National Natural Science Foundation of China(Nos.32002411,42276189)the Innovation and Entrepreneurship Project for College Students of Hohai University(No.2022102941027)the Jiangsu Innovation Center for Marine Bioresources(No.822153216)。
文摘The function of exogenous alanine(Ala)in regulating biomass accumulation,lipid production,photosynthesis,and respiration in Chlorella pyrenoidosa was studied.Result shows that the supplementation of Ala increased C.pyrenoidosa biomass and lipid production in an 8-d batch culture.The concentration of 10 mmol/L of Ala was optimum and increased the microalgal cell biomass and lipid content by 39.3%and 21.4%,respectively,compared with that in the control(0-mmol/L Ala).Ala supplementation reduced photosynthetic activity while boosting respiratory activity and pyruvate levels,indicating that C.pyrenoidosa used exogenous Ala for biomass accumulation through the respiratory metabolic process.The accelerated respiratory metabolism due to Ala supplementation elevated the substrate pool and improved the lipogenic gene expression,promoting lipid production at last.This study provided a novel method for increasing biomass accumulation and lipid production and elucidated the role of Ala in regulating lipid production.
