[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
Chronic diabetic wound remains a critical challenge suffering from the complicated negative microenvironments,such as high-glucose,excessive reactive oxygen species(ROS),hypoxia and malnutrition.Unfortunately,few stra...Chronic diabetic wound remains a critical challenge suffering from the complicated negative microenvironments,such as high-glucose,excessive reactive oxygen species(ROS),hypoxia and malnutrition.Unfortunately,few strategies have been developed to ameliorate the multiple microenvironments simultaneously.In this study,Chlorella sp.(Chlorella)hydrogels were prepared against diabetic wounds.In vitro experiments demonstrated that living Chlorella could produce dissolved oxygen by photosynthesis,actively consume glucose and deplete ROS with the inherent antioxidants,during the daytime.At night,Chlorella was inactivated in situ by chlorine dioxide with human-body harmless concentration to utilize its abundant contents.It was verified in vitro that the inactivated-Chlorella could supply nutrition,relieve inflammation and terminate the oxygen-consumption of Chlorella-respiration.The advantages of living Chlorella and its contents were integrated ingeniously.The abovementioned functions were proven to accelerate cell proliferation,migration and angiogenesis in vitro.Then,streptozotocininduced diabetic mice were employed for further validation.The in vivo outcomes confirmed that Chlorella could ameliorate the undesirable microenvironments,including hypoxia,high-glucose,excessiveROS and chronic inflammation,thereby synergistically promoting tissue regeneration.Given the results above,Chlorella is considered as a tailor-made therapeutic strategy for diabetic wound healing.展开更多
A promising microalgal strain isolated from fresh water,which can grow both autotrophically on inorganic carbon under lighting and heterotrophically on organic carbon without lighting,was identified as Chlorella sp.US...A promising microalgal strain isolated from fresh water,which can grow both autotrophically on inorganic carbon under lighting and heterotrophically on organic carbon without lighting,was identified as Chlorella sp.USTB-01 with the phylogenetic analysis based on 18S ribosomal ribonucleic acid(rRNA)gene sequences.In the heterotrophic batch culture,more than 20.0 g·L^(-1)of cell dry weight concentration(DWC)of Chlorella sp.USTB-01 was obtained at day 5,and which was used directly to seed the autotrophic culture.A novel fermentor-helical combined photobioreactor was established and used to cultivate Chlorella sp.USTB-01 for the fixation of carbon dioxide(CO_(2)).It showed that the autotrophic growth of Chlorella sp.USTB-01 in the combined photobioreactor was more effective than that in the fermentor alone and the maximum DWC of 2.5 g·L^(-1)was obtained at day 6.The highest CO_(2)fixation of 95%appeared on day 1 in the exponential growth phases of Chlorella sp.USTB-01 and 49.8%protein was found in the harvested microalgal cells.展开更多
The 96 h acute toxic effects of nano-CuO (N-CuO), micro-CuO (M-CuO) and 2+ on Chlorella sp. were investigated in this paper. The results showed that toxicities decreased in an order of Cu2+>N-CuO>M-CuO. The 96 h...The 96 h acute toxic effects of nano-CuO (N-CuO), micro-CuO (M-CuO) and 2+ on Chlorella sp. were investigated in this paper. The results showed that toxicities decreased in an order of Cu2+>N-CuO>M-CuO. The 96 h EC50 of Cu2+ on Chlorella sp. was 1.06 mg /L, and of N-CuO it was 74.61 mg /L, while no pronounced toxicity was observed when the concentration of M-CuO was lower than 160 mg/L. Further experiments were carried out in order to study the toxicity mechanism of nano-CuO on Chlorella sp.. The results of Cu2+ release from N-CuO showed less than 0.2 mg/L Cu2+ were released, so the release of Cu2+ was not responsible for the toxicity. Further experiments showed N-CuO inhibited formation of Chlorophyll A. Content of Chlorophyll A in the control group was 4.75 mg/108 cells, while it declined to 2.89 mg/108 cells for 160 mg/L N-CuO after 96 h, which indicated that N-CuO could inhibit photosynthesis of Chlorella sp.. Moreover, N-CuO condensed with algal cells. It affected the activity of SOD and POD, indicating that N-CuO could cause oxidant stress to Chlorella sp.. These may be the toxicity mechanism.展开更多
[ Objective] This paper was to evaluate the methods of breaking stiffness cell wall of Chlorella sp. and extracting and testing functional antioxidant by ethanol and DPPH method separately. [Method] Extractions were p...[ Objective] This paper was to evaluate the methods of breaking stiffness cell wall of Chlorella sp. and extracting and testing functional antioxidant by ethanol and DPPH method separately. [Method] Extractions were performed at different extraction times （60, 120 and 180 min） at 37 ℃. And the radical scavenging activity of Chlorella spo extract was assayed by the DPPH （ 1,1-Diphenyl-2- picrylhydrazy[） method. [ Result ] The optimal conditions for ethanol extraction from Chlorella sp. were ethanol concentration of 90%, substrate consistency of 5% （w/v） and treating time of 180 min, under which, a concentration of 135.5 mg/L was obtained. Antioxidant pigments obtained from alcoholic extraction from Chlorella sp. showed high free radical scavenging ability. The efficiency increased with increasing concentration of solid microalgae powder, which could reach to 88%. [ Conclusion] Ethanol extraction method is simple and feasible. However, the efficiency of extraction is not high enough, which will limit the yield of antioxidant production from economic prospective.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financially supported by the National Natural Science Foundation of China(81673830)Six Talent Peaks Project in Jiangsu Province(YY053,China)+1 种基金Major Project and Double firstclass innovative team(CPU2018GY28,China)National Science and Technology Major Project(2017zx09101001005,China)。
文摘Chronic diabetic wound remains a critical challenge suffering from the complicated negative microenvironments,such as high-glucose,excessive reactive oxygen species(ROS),hypoxia and malnutrition.Unfortunately,few strategies have been developed to ameliorate the multiple microenvironments simultaneously.In this study,Chlorella sp.(Chlorella)hydrogels were prepared against diabetic wounds.In vitro experiments demonstrated that living Chlorella could produce dissolved oxygen by photosynthesis,actively consume glucose and deplete ROS with the inherent antioxidants,during the daytime.At night,Chlorella was inactivated in situ by chlorine dioxide with human-body harmless concentration to utilize its abundant contents.It was verified in vitro that the inactivated-Chlorella could supply nutrition,relieve inflammation and terminate the oxygen-consumption of Chlorella-respiration.The advantages of living Chlorella and its contents were integrated ingeniously.The abovementioned functions were proven to accelerate cell proliferation,migration and angiogenesis in vitro.Then,streptozotocininduced diabetic mice were employed for further validation.The in vivo outcomes confirmed that Chlorella could ameliorate the undesirable microenvironments,including hypoxia,high-glucose,excessiveROS and chronic inflammation,thereby synergistically promoting tissue regeneration.Given the results above,Chlorella is considered as a tailor-made therapeutic strategy for diabetic wound healing.
基金This research was supported by PetroChina Innovation Foundation(2009D-5006-04-02)the Fundamental Research Funds for the Central Universities and the Metallurgical Foundation of University of Science and Technology Beijing.
文摘A promising microalgal strain isolated from fresh water,which can grow both autotrophically on inorganic carbon under lighting and heterotrophically on organic carbon without lighting,was identified as Chlorella sp.USTB-01 with the phylogenetic analysis based on 18S ribosomal ribonucleic acid(rRNA)gene sequences.In the heterotrophic batch culture,more than 20.0 g·L^(-1)of cell dry weight concentration(DWC)of Chlorella sp.USTB-01 was obtained at day 5,and which was used directly to seed the autotrophic culture.A novel fermentor-helical combined photobioreactor was established and used to cultivate Chlorella sp.USTB-01 for the fixation of carbon dioxide(CO_(2)).It showed that the autotrophic growth of Chlorella sp.USTB-01 in the combined photobioreactor was more effective than that in the fermentor alone and the maximum DWC of 2.5 g·L^(-1)was obtained at day 6.The highest CO_(2)fixation of 95%appeared on day 1 in the exponential growth phases of Chlorella sp.USTB-01 and 49.8%protein was found in the harvested microalgal cells.
文摘The 96 h acute toxic effects of nano-CuO (N-CuO), micro-CuO (M-CuO) and 2+ on Chlorella sp. were investigated in this paper. The results showed that toxicities decreased in an order of Cu2+>N-CuO>M-CuO. The 96 h EC50 of Cu2+ on Chlorella sp. was 1.06 mg /L, and of N-CuO it was 74.61 mg /L, while no pronounced toxicity was observed when the concentration of M-CuO was lower than 160 mg/L. Further experiments were carried out in order to study the toxicity mechanism of nano-CuO on Chlorella sp.. The results of Cu2+ release from N-CuO showed less than 0.2 mg/L Cu2+ were released, so the release of Cu2+ was not responsible for the toxicity. Further experiments showed N-CuO inhibited formation of Chlorophyll A. Content of Chlorophyll A in the control group was 4.75 mg/108 cells, while it declined to 2.89 mg/108 cells for 160 mg/L N-CuO after 96 h, which indicated that N-CuO could inhibit photosynthesis of Chlorella sp.. Moreover, N-CuO condensed with algal cells. It affected the activity of SOD and POD, indicating that N-CuO could cause oxidant stress to Chlorella sp.. These may be the toxicity mechanism.
文摘[ Objective] This paper was to evaluate the methods of breaking stiffness cell wall of Chlorella sp. and extracting and testing functional antioxidant by ethanol and DPPH method separately. [Method] Extractions were performed at different extraction times （60, 120 and 180 min） at 37 ℃. And the radical scavenging activity of Chlorella spo extract was assayed by the DPPH （ 1,1-Diphenyl-2- picrylhydrazy[） method. [ Result ] The optimal conditions for ethanol extraction from Chlorella sp. were ethanol concentration of 90%, substrate consistency of 5% （w/v） and treating time of 180 min, under which, a concentration of 135.5 mg/L was obtained. Antioxidant pigments obtained from alcoholic extraction from Chlorella sp. showed high free radical scavenging ability. The efficiency increased with increasing concentration of solid microalgae powder, which could reach to 88%. [ Conclusion] Ethanol extraction method is simple and feasible. However, the efficiency of extraction is not high enough, which will limit the yield of antioxidant production from economic prospective.
