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
Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short ...Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short time period. High Cu concentration resulted in a significant suppression in photosynthesis and respiration. The absorption flux （ABS/RC） per PSII reaction center increased with increasing Cu concentration, but the electron transport flux （ET0/RC） decreased. Excess Cu had an insignificant effect on the trapping flux （TR0/RC）. The decline in the efficiency, with which a trapped exciton can move an electron into the electron transport chain further than QA-（Ψ0）, the maximal quantum yield of primary photochemistry （φP0）, and the quantum yield of electron transport （φE0） were also observed. The amount of active PSII reaction centers per excited cross section （RC/CS） was also in consistency with the change of photosynthesis when cells were exposed to excess Cu concentration. JIP-test parameters had a good linear relationship with photosynthetic O2 evolution. These results suggested that the decrease of photosynthesis in exposure to excess Cu may be a result of the inactivation of PSII reaction centers and the inhibition of electron transport in the acceptor side.展开更多
Toxic effect of Zn（II） on a green alga （Chlorella pyrenoidosa） in the presence of sepiolite and kaolinite was investigated. The Zn-free clays were found to have a negative impact on the growth of C. pyrenoidosa in...Toxic effect of Zn（II） on a green alga （Chlorella pyrenoidosa） in the presence of sepiolite and kaolinite was investigated. The Zn-free clays were found to have a negative impact on the growth of C. pyrenoidosa in comparison with control samples （without adding any clay or Zn（II））. When Zn（II） was added, the algae in the presence of clays could be better survived than the control samples, which was actually caused by a decrease in Zn（II） concentration in the solution owing to the adsorption of Zn（II） on the clays. When the solution system was diluted, the growth of algae could be further inhibited as compared to that in a system which had the same initial Zn（II） concentration as in the diluted system. This in fact resulted from desorption of Zn（II） from the zinc-contaminated clays, although the effect varied according to the different desorption capabilities of sepiolite and kaolinite. Therefore the adsorption and desorption processes of Zn（H） played an important part in its toxicity, and adsorption and desorption of pollutants on soils/sediments should be well considered in natural eco-environmental systems before their risk of toxicity to aquatic organisms was assessed objectively.展开更多
Intensive use of sulfamethazine(SM_2) in aquaculture has resulted in some detrimental effects to non-targeted organisms. In order to assess its potential ecological risk, it is crucial to have a good understanding on ...Intensive use of sulfamethazine(SM_2) in aquaculture has resulted in some detrimental effects to non-targeted organisms. In order to assess its potential ecological risk, it is crucial to have a good understanding on the bioaccumulation and biodegradation of SM_2 in Chlorella pyrenoidosa. The microalgae were treated with 2, 4, and 8 mg L^(-1) of sulfamethazine for 13 days, respectively, showing that the inhibition effects of sulfamethazine on the growth of Chlorella pyrenoidosa increased progressively as the concentrations of sulfamethazine increasing from 2 to 8 mg L^(-1). The peak concentrations of sulfamethazine accumulated in C. pyrenoidosa were 0.225, 0.325, and 0.596 ng per mg FW on day 13 for three treatment groups, respectively, showing a great ability to deplete sulfamethazine from the culture media. On day 13, the percentages of biotic degradation were 48.45%, 60.21% and 69.93%, respectively. The EC_(50) of 10.05 mg L^(-1) was derived which showed no significant risk for C. pyrenoidosa with a calculated risk quotient < 1. The activities of superoxide dismutase and catalase increased progressively in response to sulfamethazine and showed a positive correlation to the treatment concentrations. The highest superoxide dismutase activity was achieved at the concentration of 8 mg L^(-1) after 2 d of exposure, which was 1.89 folds higher than that of the control. The activity of catalase has a similar pattern to that of superoxide dismutase with the maximum activity achieved at day 2, which was 3.11 folds higher compared to that of the control. In contrast to superoxide dismutase and catalase, the maximum glutathione S-transferase activity was observed at day 6, showing 2.2 folds higher than that of the control.展开更多
Chlorella pyrenoidosa(Chlorophyceae)is widely cultured for production of health food and animal feed.In outdoors,mass cultivation of C.pyrenoidosa often suffers from high temperature.A better understanding of the effe...Chlorella pyrenoidosa(Chlorophyceae)is widely cultured for production of health food and animal feed.In outdoors,mass cultivation of C.pyrenoidosa often suffers from high temperature.A better understanding of the effects of high temperature on photosynthesis and photoprotection can help optimize the productivity ofC.pyrenoidosa cultures.In this study,we investigated effect of high temperature(35,38,or 41℃)on the balance between photosynthetic light absorption and energy utilization of C.pyrenoidosa.In contrast to 30℃,higher temperature of 35 or 38℃did not inhibit the growth of C.pyrenoidosa.Treatment in 35℃maintained the balance.Moreover,the PSI acceptor side in 38℃was over-reduced and PSII reaction centers were over-excited under strong light,which destroyed the balance and generated active oxygen species(AOS).However,the activated antioxidant enzymes might remove completely the over-production of AOS,thereby protect C.pyrenoidosa cells from photodamage.It shows that this C.pyrenoidosa strain could tolerate as high as 38℃.Furthermore,treatment in 41℃resulted in more lack of the balance than that in 38℃.However,the activities of antioxidant enzymes stopped increasing in 41℃,and were not strong enough to remove the excess AOS.Therefore,treatment in 41℃could decrease the growth ofC.pyrenoidosa.In addition,strong and longtime light exposure would cause serious photodamage to C.pyrenoidosa cells.展开更多
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.
基金supported by the National Natural Science Foundation of China (No. 40676079, 40976078)the National Key Technology R&D Program (No.2008ZX07211-003)
文摘Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short time period. High Cu concentration resulted in a significant suppression in photosynthesis and respiration. The absorption flux （ABS/RC） per PSII reaction center increased with increasing Cu concentration, but the electron transport flux （ET0/RC） decreased. Excess Cu had an insignificant effect on the trapping flux （TR0/RC）. The decline in the efficiency, with which a trapped exciton can move an electron into the electron transport chain further than QA-（Ψ0）, the maximal quantum yield of primary photochemistry （φP0）, and the quantum yield of electron transport （φE0） were also observed. The amount of active PSII reaction centers per excited cross section （RC/CS） was also in consistency with the change of photosynthesis when cells were exposed to excess Cu concentration. JIP-test parameters had a good linear relationship with photosynthetic O2 evolution. These results suggested that the decrease of photosynthesis in exposure to excess Cu may be a result of the inactivation of PSII reaction centers and the inhibition of electron transport in the acceptor side.
基金Project supported by the National Basic Research Program(973)of China(No. 2002CB412308)National Natural Science Foundation of China(No. 20537020).
文摘Toxic effect of Zn（II） on a green alga （Chlorella pyrenoidosa） in the presence of sepiolite and kaolinite was investigated. The Zn-free clays were found to have a negative impact on the growth of C. pyrenoidosa in comparison with control samples （without adding any clay or Zn（II））. When Zn（II） was added, the algae in the presence of clays could be better survived than the control samples, which was actually caused by a decrease in Zn（II） concentration in the solution owing to the adsorption of Zn（II） on the clays. When the solution system was diluted, the growth of algae could be further inhibited as compared to that in a system which had the same initial Zn（II） concentration as in the diluted system. This in fact resulted from desorption of Zn（II） from the zinc-contaminated clays, although the effect varied according to the different desorption capabilities of sepiolite and kaolinite. Therefore the adsorption and desorption processes of Zn（H） played an important part in its toxicity, and adsorption and desorption of pollutants on soils/sediments should be well considered in natural eco-environmental systems before their risk of toxicity to aquatic organisms was assessed objectively.
基金supported by the earmarked fund for the Modern Agro-Industry Technology Research System (CARS-47)the Program of Shandong Leading Talent (No.LJNY2015002)the AoShan Scientific and Technological Innovation Project which was financially backed by Qingdao National Laboratory for Marine Science and Technology (No.2015ASKJ02)
文摘Intensive use of sulfamethazine(SM_2) in aquaculture has resulted in some detrimental effects to non-targeted organisms. In order to assess its potential ecological risk, it is crucial to have a good understanding on the bioaccumulation and biodegradation of SM_2 in Chlorella pyrenoidosa. The microalgae were treated with 2, 4, and 8 mg L^(-1) of sulfamethazine for 13 days, respectively, showing that the inhibition effects of sulfamethazine on the growth of Chlorella pyrenoidosa increased progressively as the concentrations of sulfamethazine increasing from 2 to 8 mg L^(-1). The peak concentrations of sulfamethazine accumulated in C. pyrenoidosa were 0.225, 0.325, and 0.596 ng per mg FW on day 13 for three treatment groups, respectively, showing a great ability to deplete sulfamethazine from the culture media. On day 13, the percentages of biotic degradation were 48.45%, 60.21% and 69.93%, respectively. The EC_(50) of 10.05 mg L^(-1) was derived which showed no significant risk for C. pyrenoidosa with a calculated risk quotient < 1. The activities of superoxide dismutase and catalase increased progressively in response to sulfamethazine and showed a positive correlation to the treatment concentrations. The highest superoxide dismutase activity was achieved at the concentration of 8 mg L^(-1) after 2 d of exposure, which was 1.89 folds higher than that of the control. The activity of catalase has a similar pattern to that of superoxide dismutase with the maximum activity achieved at day 2, which was 3.11 folds higher compared to that of the control. In contrast to superoxide dismutase and catalase, the maximum glutathione S-transferase activity was observed at day 6, showing 2.2 folds higher than that of the control.
基金Supported by the Shandong Provincial Natural Science Foundation,China(No.ZR2017QC008)
文摘Chlorella pyrenoidosa(Chlorophyceae)is widely cultured for production of health food and animal feed.In outdoors,mass cultivation of C.pyrenoidosa often suffers from high temperature.A better understanding of the effects of high temperature on photosynthesis and photoprotection can help optimize the productivity ofC.pyrenoidosa cultures.In this study,we investigated effect of high temperature(35,38,or 41℃)on the balance between photosynthetic light absorption and energy utilization of C.pyrenoidosa.In contrast to 30℃,higher temperature of 35 or 38℃did not inhibit the growth of C.pyrenoidosa.Treatment in 35℃maintained the balance.Moreover,the PSI acceptor side in 38℃was over-reduced and PSII reaction centers were over-excited under strong light,which destroyed the balance and generated active oxygen species(AOS).However,the activated antioxidant enzymes might remove completely the over-production of AOS,thereby protect C.pyrenoidosa cells from photodamage.It shows that this C.pyrenoidosa strain could tolerate as high as 38℃.Furthermore,treatment in 41℃resulted in more lack of the balance than that in 38℃.However,the activities of antioxidant enzymes stopped increasing in 41℃,and were not strong enough to remove the excess AOS.Therefore,treatment in 41℃could decrease the growth ofC.pyrenoidosa.In addition,strong and longtime light exposure would cause serious photodamage to C.pyrenoidosa cells.
