Sustainability and eco-friendliness have both engendered research on alternative replacement of fossil fuel. This study was aimed at determining the effects of varying levels of glucose (10 ~ 40 g/L), and glycerol (0....Sustainability and eco-friendliness have both engendered research on alternative replacement of fossil fuel. This study was aimed at determining the effects of varying levels of glucose (10 ~ 40 g/L), and glycerol (0.25 ~ 1.0 mL/L) on the heterotrophic and mixotrophic growth and lipid production by Dictyosphaerium sp. The microalga was cultivated in 2000 mL amber-coloured bottles each containing 1000 mL of a sterile modified BG-11 medium at pH of 7.3. Each bottle was inoculated with a one-week-old pure culture of the isolate (inoculum ratio = 15%) and incubated in the dark at room temperature (30°C ± 2°C) for 10 d. Dictyosphaerium sp. showed the ability to grow heterotrophically and mixotrophically on glucose and on glycerol as a sole carbon substrates. Biomass productivity and specific growth rates did not vary when the initial medium glucose was varied. Lipid accumulation was not dependent on the initial medium glycerol contents. The mean lipid content and productivity of the organism in the present study were high enough to be utilised for industrial processes. Growth and lipid accumulations were better in mixotrophic cultures than both heterotrophic and autotrophic. However, both were better than autotrophic. The percentage compositions of the major fatty acids from Dictyosphaerium sp. grown under different culture conditions show at least five components each. The carbon skeletons eluted ranged from C14 to C22. Oleic acid was a major component of all the fatty acids, which confirm the suitability of the use of the oil for biodiesel production.展开更多
As a way of making algal feedstock feasible for biofuel production, simulta<span>neous utilization of microalga <i>Dictyosphaerium</i> sp. LC172264 for cassava</span> wastewater remediation and...As a way of making algal feedstock feasible for biofuel production, simulta<span>neous utilization of microalga <i>Dictyosphaerium</i> sp. LC172264 for cassava</span> wastewater remediation and accumulation of lipids for biodiesel production was investigated. The algal biomass, lipid contents and composition were measured from the autotrophic, heterotrophic and mixotrophic cultured algal cells. Physicochemical parameters of the cassava wastewater and bioremediation potentials were measured. Biodiesel properties were deduced and compared with the standards. The results showed that mixotrophic culture was the best for both biomass accumulation (1.022 g/L) and lipid contents (24.53%). Irrespective of the culture condition, the predominant fatty acids were similar and included 11-Octadecenoic acid (vaccenic acid (C<sub>19</sub>H<sub>36</sub>O<sub>2</sub>), oleic acid (C<sub>18</sub>H<sub>34</sub>O<sub>2</sub>) and 14-methyl pentadecanoic acid (isopalmitic acid (C<sub>17</sub>H<sub>34</sub>O<sub>2</sub>). The percentage reduction of total dissolved solids was 79.32% and 89.78% for heterotrophy and mixotrophy respectively. Biochemical oxygen demand was 72.95% and 89.35%, chemical oxygen demand was 72.19% and 84.03% whereas cyanide contents reduced from the initial value of 450 mg/L to 93.105 (79.31%) and 85.365 mg/L (81.03%) respectively. <i>Dictyosphaerium</i> sp. showed good growth and lipid production under mixotrophic condition and produced good quality biodiesel under the three cultivation modes. Even though both mixotrophic and heterotrophic conditions had good promise of cassava wastewater remediation by <i>Dictyosphaerium</i> sp., mixotrophy showed superiority.展开更多
Sulfonamides(SAs)are common antimicrobial drugs,which are frequently detected in surface water systems,and are difficult to degrade,posing a potential threat to the aquatic environment.However,little is known about th...Sulfonamides(SAs)are common antimicrobial drugs,which are frequently detected in surface water systems,and are difficult to degrade,posing a potential threat to the aquatic environment.However,little is known about the potential adverse effects of SAs on nontarget organisms(e.g.,microalgae)in the aquatic ecosystem.In this study,the effect of SAs(sulfadiazine(SD),sulfamerazine(SM1),and sulfamethazine(SM2)at 1,5,20,and 50 mg/L concentrations,respectively)on the freshwater microalga Dictyosphaerium sp.was investigated,with respect to changes of biomass and chlorophyll a content and induction of extracellular polymer substances(EPS),including protein and polysaccharide contents.At the same time,the residue of SAs was determined.The results showed that Dictyosphaerium sp.was tolerant to the three SAs,and the chlorophyll a content in Dictyosphaerium sp.significantly decreased on day 7,followed by a"compensation phenomena".The increase in protein and polysaccharide contents played a defensive role in Dictyosphaerium sp.against antibiotic stress,and there was a strong positive correlation between polysaccharide contents and antibiotic concentrations.Dictyosphaerium sp.exhibited 35%–45%,30%–42%,and 26%–51%removal of SD,SM1,and SM2,respectively.This study is helpful to understand the changes of EPS in the defense process of microalgae under the action of antibiotics,and provides a new insight for the ecological removal of antibiotic pollution in natural surface water system.展开更多
文摘Sustainability and eco-friendliness have both engendered research on alternative replacement of fossil fuel. This study was aimed at determining the effects of varying levels of glucose (10 ~ 40 g/L), and glycerol (0.25 ~ 1.0 mL/L) on the heterotrophic and mixotrophic growth and lipid production by Dictyosphaerium sp. The microalga was cultivated in 2000 mL amber-coloured bottles each containing 1000 mL of a sterile modified BG-11 medium at pH of 7.3. Each bottle was inoculated with a one-week-old pure culture of the isolate (inoculum ratio = 15%) and incubated in the dark at room temperature (30°C ± 2°C) for 10 d. Dictyosphaerium sp. showed the ability to grow heterotrophically and mixotrophically on glucose and on glycerol as a sole carbon substrates. Biomass productivity and specific growth rates did not vary when the initial medium glucose was varied. Lipid accumulation was not dependent on the initial medium glycerol contents. The mean lipid content and productivity of the organism in the present study were high enough to be utilised for industrial processes. Growth and lipid accumulations were better in mixotrophic cultures than both heterotrophic and autotrophic. However, both were better than autotrophic. The percentage compositions of the major fatty acids from Dictyosphaerium sp. grown under different culture conditions show at least five components each. The carbon skeletons eluted ranged from C14 to C22. Oleic acid was a major component of all the fatty acids, which confirm the suitability of the use of the oil for biodiesel production.
文摘As a way of making algal feedstock feasible for biofuel production, simulta<span>neous utilization of microalga <i>Dictyosphaerium</i> sp. LC172264 for cassava</span> wastewater remediation and accumulation of lipids for biodiesel production was investigated. The algal biomass, lipid contents and composition were measured from the autotrophic, heterotrophic and mixotrophic cultured algal cells. Physicochemical parameters of the cassava wastewater and bioremediation potentials were measured. Biodiesel properties were deduced and compared with the standards. The results showed that mixotrophic culture was the best for both biomass accumulation (1.022 g/L) and lipid contents (24.53%). Irrespective of the culture condition, the predominant fatty acids were similar and included 11-Octadecenoic acid (vaccenic acid (C<sub>19</sub>H<sub>36</sub>O<sub>2</sub>), oleic acid (C<sub>18</sub>H<sub>34</sub>O<sub>2</sub>) and 14-methyl pentadecanoic acid (isopalmitic acid (C<sub>17</sub>H<sub>34</sub>O<sub>2</sub>). The percentage reduction of total dissolved solids was 79.32% and 89.78% for heterotrophy and mixotrophy respectively. Biochemical oxygen demand was 72.95% and 89.35%, chemical oxygen demand was 72.19% and 84.03% whereas cyanide contents reduced from the initial value of 450 mg/L to 93.105 (79.31%) and 85.365 mg/L (81.03%) respectively. <i>Dictyosphaerium</i> sp. showed good growth and lipid production under mixotrophic condition and produced good quality biodiesel under the three cultivation modes. Even though both mixotrophic and heterotrophic conditions had good promise of cassava wastewater remediation by <i>Dictyosphaerium</i> sp., mixotrophy showed superiority.
基金supported by the Chinese Major Science and Technology Program for Water Pollution Control and Treat-ment(No.2017ZX07207002-03)the Science and Technology Commission of Shanghai Municipality(Nos.19050501900 and 19DZ1204504)the Scientific Research Fund for Young Teachers of Shanghai Ocean University。
文摘Sulfonamides(SAs)are common antimicrobial drugs,which are frequently detected in surface water systems,and are difficult to degrade,posing a potential threat to the aquatic environment.However,little is known about the potential adverse effects of SAs on nontarget organisms(e.g.,microalgae)in the aquatic ecosystem.In this study,the effect of SAs(sulfadiazine(SD),sulfamerazine(SM1),and sulfamethazine(SM2)at 1,5,20,and 50 mg/L concentrations,respectively)on the freshwater microalga Dictyosphaerium sp.was investigated,with respect to changes of biomass and chlorophyll a content and induction of extracellular polymer substances(EPS),including protein and polysaccharide contents.At the same time,the residue of SAs was determined.The results showed that Dictyosphaerium sp.was tolerant to the three SAs,and the chlorophyll a content in Dictyosphaerium sp.significantly decreased on day 7,followed by a"compensation phenomena".The increase in protein and polysaccharide contents played a defensive role in Dictyosphaerium sp.against antibiotic stress,and there was a strong positive correlation between polysaccharide contents and antibiotic concentrations.Dictyosphaerium sp.exhibited 35%–45%,30%–42%,and 26%–51%removal of SD,SM1,and SM2,respectively.This study is helpful to understand the changes of EPS in the defense process of microalgae under the action of antibiotics,and provides a new insight for the ecological removal of antibiotic pollution in natural surface water system.
