The fast growing unicellular green microalgae Chlorella protothecoides has attracted interest as a promising organism for commercial production of a high-value carotenoid, lutein, by heterotrophic fermentation. Effect...The fast growing unicellular green microalgae Chlorella protothecoides has attracted interest as a promising organism for commercial production of a high-value carotenoid, lutein, by heterotrophic fermentation. Effects of two oxidant-forming reactive oxygen species (ROS) on the biomass concen-tration, and yield and content of lutein in batch culture of heterotrophic Chlorella protothecoides were investigated in this study. The addition of 0.1 mmol/L H2O2 and 0.01 mmol/L NaClO plus 0.5 mmol/L Fe2+ to the culture led to the generation of ·OH and enhanced the lutein content from 1.75 to 1.90 and 1.95 mg/g, respectively. The lutein content further increased to 1.98 mg/g when 0.01 mmol/L H2O2 and 0.5 mmol/L NaClO were added to generate 1O2. The maximum yield of lutein (28.5, 29.8 and 31.4 mg/L) and a high biomass concentration (15.0, 15.3 and 15.9 g/L) were also achieved through the above treatments. The results indicated that 1O2 could promote lutein formation and enhance lutein production in hetero-trophic Chlorella protothecoides. Moreover, 1O2 produced from the reaction of H2O2 and NaClO was more effective in enhancing lutein production and reducing biomass loss than ·OH from the reaction of H2O2 or NaClO plus Fe2+.展开更多
Effects of inhibitors and glucose on cytochrome and alternative respiration and on adenylate energy charge (AEC) in glucose starved Chlorella protothecoides were investigated. 1 mmol/L azide (NaN 3), which immediate...Effects of inhibitors and glucose on cytochrome and alternative respiration and on adenylate energy charge (AEC) in glucose starved Chlorella protothecoides were investigated. 1 mmol/L azide (NaN 3), which immediately caused an increase of O 2 uptake by inhibiting the cytochrome pathway and stimulating alternative respiration, resulted in a decrease of AEC value from 0.83 to 0.34 within 3 minutes. When 1 mmol/L salicylhydroxamic acid (SHAM) was added into the cell suspension, there was no apparent variation in AEC. Adding NaN 3 and SHAM together into cell suspension to inhibit both cytochrome and alternative pathways showed a same change of AEC as that of adding NaN 3 alone. When 2.0 mmol/L of glucose was added to a suspension of glucose starved cells, the O 2 uptake rate was immediately stimulated from 0.81 up to 1.34 [μmol/L O 2[DK]·min -1 ·(mL PCV) -1 ]. The respiration stimulated by glucose could be inhibited about 20% by adding 1 mmol/L SHAM. It was found by titration with SHAM in the absence and presence of NaN 3 that 53% of O 2 uptake went through the cytochrome pathway and 45% of the alternate pathway was operational in enhanced respiration. It implied that induced operation of the alternative respiratory pathway probably resulted from the burst of the electron flux into the electron transport chain by glucose stimulation. . The respiration stimulated by glucose could be inhibited about 20% by adding 1 mmol/L SHAM. It was found by titration with SHAM in the absence and presence of NaN 3 that 53% of O 2 uptake went through the cytochrome pathway and 45% of the alternate pathway was operational in enhanced respiration. It implied that induced operation of the alternative respiratory pathway probably resulted from the burst of the electron flux into the electron transport chain by glucose stimulation.展开更多
The relative contents of normal alkanes and isoprenoid alkanes from pyrolysed products of green alga Chlorella protothecoides increased when the algal cell subject to hydrolysis and bacterial degradation were used. Th...The relative contents of normal alkanes and isoprenoid alkanes from pyrolysed products of green alga Chlorella protothecoides increased when the algal cell subject to hydrolysis and bacterial degradation were used. Their value of C 23 -/C 24 + and the rate of Pr/C 17 increased greatly whereas the contents of C 20 alkenes were remarkably low compared with that from untreated sample (as control). These results are more analogous to the formation process of hydrocarbons derived from algae in natural geological environment.展开更多
基金Supported by the National Key Project of Sci & Tech Supporting ProgramsFunded by Ministry of Science & Technology of China (Grant No. 2006BAD27B03)+1 种基金Sci & Tech Project of Guangzhou (Grant No. 2005Z3-E0331)Sci & Tech Project of Guangdong (Grant No. 20052050166)
文摘The fast growing unicellular green microalgae Chlorella protothecoides has attracted interest as a promising organism for commercial production of a high-value carotenoid, lutein, by heterotrophic fermentation. Effects of two oxidant-forming reactive oxygen species (ROS) on the biomass concen-tration, and yield and content of lutein in batch culture of heterotrophic Chlorella protothecoides were investigated in this study. The addition of 0.1 mmol/L H2O2 and 0.01 mmol/L NaClO plus 0.5 mmol/L Fe2+ to the culture led to the generation of ·OH and enhanced the lutein content from 1.75 to 1.90 and 1.95 mg/g, respectively. The lutein content further increased to 1.98 mg/g when 0.01 mmol/L H2O2 and 0.5 mmol/L NaClO were added to generate 1O2. The maximum yield of lutein (28.5, 29.8 and 31.4 mg/L) and a high biomass concentration (15.0, 15.3 and 15.9 g/L) were also achieved through the above treatments. The results indicated that 1O2 could promote lutein formation and enhance lutein production in hetero-trophic Chlorella protothecoides. Moreover, 1O2 produced from the reaction of H2O2 and NaClO was more effective in enhancing lutein production and reducing biomass loss than ·OH from the reaction of H2O2 or NaClO plus Fe2+.
基金the National Natural Science Foundationof China(No. 39870 0 6 4and30 0 70 0 6 5 ) partly bythe State Key Basic Research and Developm entProgram s of China(No.G19980 10 10 0 and G19990 433)
文摘Effects of inhibitors and glucose on cytochrome and alternative respiration and on adenylate energy charge (AEC) in glucose starved Chlorella protothecoides were investigated. 1 mmol/L azide (NaN 3), which immediately caused an increase of O 2 uptake by inhibiting the cytochrome pathway and stimulating alternative respiration, resulted in a decrease of AEC value from 0.83 to 0.34 within 3 minutes. When 1 mmol/L salicylhydroxamic acid (SHAM) was added into the cell suspension, there was no apparent variation in AEC. Adding NaN 3 and SHAM together into cell suspension to inhibit both cytochrome and alternative pathways showed a same change of AEC as that of adding NaN 3 alone. When 2.0 mmol/L of glucose was added to a suspension of glucose starved cells, the O 2 uptake rate was immediately stimulated from 0.81 up to 1.34 [μmol/L O 2[DK]·min -1 ·(mL PCV) -1 ]. The respiration stimulated by glucose could be inhibited about 20% by adding 1 mmol/L SHAM. It was found by titration with SHAM in the absence and presence of NaN 3 that 53% of O 2 uptake went through the cytochrome pathway and 45% of the alternate pathway was operational in enhanced respiration. It implied that induced operation of the alternative respiratory pathway probably resulted from the burst of the electron flux into the electron transport chain by glucose stimulation. . The respiration stimulated by glucose could be inhibited about 20% by adding 1 mmol/L SHAM. It was found by titration with SHAM in the absence and presence of NaN 3 that 53% of O 2 uptake went through the cytochrome pathway and 45% of the alternate pathway was operational in enhanced respiration. It implied that induced operation of the alternative respiratory pathway probably resulted from the burst of the electron flux into the electron transport chain by glucose stimulation.
文摘The relative contents of normal alkanes and isoprenoid alkanes from pyrolysed products of green alga Chlorella protothecoides increased when the algal cell subject to hydrolysis and bacterial degradation were used. Their value of C 23 -/C 24 + and the rate of Pr/C 17 increased greatly whereas the contents of C 20 alkenes were remarkably low compared with that from untreated sample (as control). These results are more analogous to the formation process of hydrocarbons derived from algae in natural geological environment.
