The effects of monosulfuron on growth and photosynthetic pigments of the nitrogen-fixing cyanobacterium Anabaena flos-aquae grown exposed to 2000-, 3000-, and 4000-lux light intensity were studied. Exposed to three li...The effects of monosulfuron on growth and photosynthetic pigments of the nitrogen-fixing cyanobacterium Anabaena flos-aquae grown exposed to 2000-, 3000-, and 4000-lux light intensity were studied. Exposed to three light intensities, the seven concentrations of monosulfuron tested can significantly inhibit algal growth in a dose-dependent manner. The cell numbers and growth rate were decreased with the increase in mono-sulfuron concentration, and A. flos-aquae had different degrees of sensitivity to monosulfuron with the most sensitive light intensity being 4000-lux followed by 3000-lux and 2000-lux. The herbicide monosulfuron appeared to have different effects on the synthesis of photosynthetic pigments. The chlorophyll appeared to tackle monosulfuron concentrations. The caroteniod content of algae treated with 0.008 and 0.08 mg/L monosulfuron exposed to 2000-lux had a different stimulatory effect from that of treatments exposed to 3000-lux and 4000-lux, but an inhibitory effect at concentration above 0.8 mg/L. The effect of monosulfuron on biliprotein in cells of A. flos-aquae exposed three light intensities displayed contrary dose dependence.展开更多
Turbulent mixing, in particular on a small scale, aff ects the growth of microalgae by changing diff usive sublayers and regulating nutrient fluxes of cells. We tested the nutrient flux hypothesis by evaluating the ce...Turbulent mixing, in particular on a small scale, aff ects the growth of microalgae by changing diff usive sublayers and regulating nutrient fluxes of cells. We tested the nutrient flux hypothesis by evaluating the cellular stoichiometry and phosphorus storage of microalgae under dif ferent turbulent mixing conditions. A phanizomenon flos-aquae were cultivated in dif ferent stirring batch reactors with turbulent dissipation rates ranging from 0.001 51 m2/s 3 to 0.050 58 m 2/s 3, the latter being the highest range observed in natural aquatic systems. Samples were taken in the exponential growth phase and compared with samples taken when the reactor was completely stagnant. Results indicate that, within a certain range, turbulent mixing stimulates the growth of A. flos-aquae. An inhibitory ef fect on growth rate was observed at the higher range. Photosynthesis activity, in terms of maximum ef fective quantum yield of PSII(the ratio of F v/F m) and cellular chlorophyll a, did not change significantly in response to turbulence. However, Chl a/C mass ratio and C/N molar ratio, showed a unimodal response under a gradient of turbulent mixing, similar to growth rate. Moreover, we found that increases in turbulent mixing might stimulate respiration rates, which might lead to the use of polyphosphate for the synthesis of cellular constituents. More research is required to test and verify the hypothesis that turbulent mixing changes the dif fusive sublayer, regulating the nutrient flux of cells.展开更多
Cyanobacterial blooms have become a serious global environmental issue due to their potential risk for releasing detrimental secondary metabolites into aquatic ecosystems,posing a great threat to water quality managem...Cyanobacterial blooms have become a serious global environmental issue due to their potential risk for releasing detrimental secondary metabolites into aquatic ecosystems,posing a great threat to water quality management for public health authorities.Aphanizomenon,a common filamentous cyanobacterial genus belonging to Nostocales,is under particular concern because its several members are able to form harmful blooms.Furthermore,succession of bloom between A.flos-aquae and Microcystis occurs in many natural lakes.To evaluate the competitiveness of A.flos-aquae vs.M.aeruginosa,two sets of experiments at different ratios of biomass at 15℃and 25℃were conducted.Results show that at 15℃,the two species were able to coexist,and A.flos-aquae showed a specific higher growth rate,and its growth was promoted by the presence of M.aeruginosa.At 25℃,the growth of A.flos-aquae was inhibited by the biomass of M.aeruginosa,and M.aeruginosa suppressed A.flos-aquae in competition.Additionally,the vegetative cell size of A.flos-aquae was significantly influenced by the co-culture with M.aeruginosa,whereas the filament length of A.flos-aquae was not significantly affected.This study confirms that temperature is the dominating factor on the succession of A.flos-aquae and M.aeruginosa of a different biomass.展开更多
The effects of light, temperature, and coculture on the intracellular microcystin-LR(MCLR) quota of M icrocystis aeruginosa were evaluated based on coculture experiments with nontoxic Dolichospermum( Anabaena) fl os- ...The effects of light, temperature, and coculture on the intracellular microcystin-LR(MCLR) quota of M icrocystis aeruginosa were evaluated based on coculture experiments with nontoxic Dolichospermum( Anabaena) fl os- aquae. The MC-LR quota and transcription of m cy B and m cy D genes encoding MC synthetases in M. aeruginosa were evaluated on the basis of cell counts, high-performance liquid chromatography, and reverse-transcription quantitative real-time PCR. The MC-LR quotas of M. aeruginosa in coculture with a 1/1 ratio of inoculum of the two species were signifi cantly lower relative to monocultures 6-d after inoculation. Decreased MC-LR quotas under coculture conditions were enhanced by increasing the D. fl os- aquae to M. aeruginosa ratio in the inoculum and by environmental factors, such as temperature and light intensity. Moreover, the transcriptional concentrations of mcy B and mcy D genes in M. aeruginosa were signifi cantly inhibited by D. fl os- aquae competition in coculture(P <0.01), lowered to 20% of initial concentrations within 8 days. These data suggested that coculture effects by D. fl os- aquae not only reduced M. aeruginosa 's intracellular MC-LR quota via inhibition of genes encoding MC synthetases, but also that this effect was regulated by environmental factors, including temperature and light intensities.展开更多
[Objective] The aim was to explore the relationship between alage-lysing bacterium and Anabaena flosaquae so as to provide reference for the control of bloom. [Method] An algae-lysing bacterium strain named S7 was iso...[Objective] The aim was to explore the relationship between alage-lysing bacterium and Anabaena flosaquae so as to provide reference for the control of bloom. [Method] An algae-lysing bacterium strain named S7 was isolated from eu- trophic river. The lyric efficiency and performing mode of S7 strain to Anabaena flos- aquae was studied. Influence of different environmental factors and the relationship between S7 strain and Anabaena flosaquae was also studied, and then the bacteri- um strain was physiologically identified. [Result] More than 90% of Anabaena flos- aquae had been removed by 7 d when the volume ratio of medium to algae solu- tion was 30%, the pH was 9 and the temperature was 35 ℃. These results also showed that a mutual inhibit relationship existed between S7 strain and Anabaena flos-aquae. The S7 strain killed the algae by indirectly through certain lyric agents in absence of direct contact with the target but by secreting metabolites. Moreover, these lyric agents also had the thermostability. 16SrDNA sequence analysis showed that S7 strain belonged to Chryseobacterium sp. [Conclusion] The examined Poly-p proved that S7 strain is polyphosphate accumulating bacteria （PAOs） and has better lyric efficiency.展开更多
文摘The effects of monosulfuron on growth and photosynthetic pigments of the nitrogen-fixing cyanobacterium Anabaena flos-aquae grown exposed to 2000-, 3000-, and 4000-lux light intensity were studied. Exposed to three light intensities, the seven concentrations of monosulfuron tested can significantly inhibit algal growth in a dose-dependent manner. The cell numbers and growth rate were decreased with the increase in mono-sulfuron concentration, and A. flos-aquae had different degrees of sensitivity to monosulfuron with the most sensitive light intensity being 4000-lux followed by 3000-lux and 2000-lux. The herbicide monosulfuron appeared to have different effects on the synthesis of photosynthetic pigments. The chlorophyll appeared to tackle monosulfuron concentrations. The caroteniod content of algae treated with 0.008 and 0.08 mg/L monosulfuron exposed to 2000-lux had a different stimulatory effect from that of treatments exposed to 3000-lux and 4000-lux, but an inhibitory effect at concentration above 0.8 mg/L. The effect of monosulfuron on biliprotein in cells of A. flos-aquae exposed three light intensities displayed contrary dose dependence.
基金Supported by the National Natural Science Foundation of China(Nos.51309220,51679226)the National Key SandT Project on Water Pollution Control and Treatment(Nos.2014ZX07104-006,2015ZX07103-007)the Western Action Program funded by the Chinese Academy of Sciences(No.KZCX2-XB3-14)
文摘Turbulent mixing, in particular on a small scale, aff ects the growth of microalgae by changing diff usive sublayers and regulating nutrient fluxes of cells. We tested the nutrient flux hypothesis by evaluating the cellular stoichiometry and phosphorus storage of microalgae under dif ferent turbulent mixing conditions. A phanizomenon flos-aquae were cultivated in dif ferent stirring batch reactors with turbulent dissipation rates ranging from 0.001 51 m2/s 3 to 0.050 58 m 2/s 3, the latter being the highest range observed in natural aquatic systems. Samples were taken in the exponential growth phase and compared with samples taken when the reactor was completely stagnant. Results indicate that, within a certain range, turbulent mixing stimulates the growth of A. flos-aquae. An inhibitory ef fect on growth rate was observed at the higher range. Photosynthesis activity, in terms of maximum ef fective quantum yield of PSII(the ratio of F v/F m) and cellular chlorophyll a, did not change significantly in response to turbulence. However, Chl a/C mass ratio and C/N molar ratio, showed a unimodal response under a gradient of turbulent mixing, similar to growth rate. Moreover, we found that increases in turbulent mixing might stimulate respiration rates, which might lead to the use of polyphosphate for the synthesis of cellular constituents. More research is required to test and verify the hypothesis that turbulent mixing changes the dif fusive sublayer, regulating the nutrient flux of cells.
基金Supported by the National Key Research and Development Program of China(No.2017YFA0605201)the Major Project of Natural Science Foundation of Zhejiang Province(No.LD21C030001)+2 种基金the National Natural Science Foundation of China(No.51779247)the Controlling Technology of Cyanobacterial Bloom in the Major Lakes of Wuhan city(No.HBT-16200117-201482)the Featured Institute Service Project from Institute of Hydrobiology,Chinese Academy of Sciences(No.Y85Z061601)。
文摘Cyanobacterial blooms have become a serious global environmental issue due to their potential risk for releasing detrimental secondary metabolites into aquatic ecosystems,posing a great threat to water quality management for public health authorities.Aphanizomenon,a common filamentous cyanobacterial genus belonging to Nostocales,is under particular concern because its several members are able to form harmful blooms.Furthermore,succession of bloom between A.flos-aquae and Microcystis occurs in many natural lakes.To evaluate the competitiveness of A.flos-aquae vs.M.aeruginosa,two sets of experiments at different ratios of biomass at 15℃and 25℃were conducted.Results show that at 15℃,the two species were able to coexist,and A.flos-aquae showed a specific higher growth rate,and its growth was promoted by the presence of M.aeruginosa.At 25℃,the growth of A.flos-aquae was inhibited by the biomass of M.aeruginosa,and M.aeruginosa suppressed A.flos-aquae in competition.Additionally,the vegetative cell size of A.flos-aquae was significantly influenced by the co-culture with M.aeruginosa,whereas the filament length of A.flos-aquae was not significantly affected.This study confirms that temperature is the dominating factor on the succession of A.flos-aquae and M.aeruginosa of a different biomass.
基金Supported by the National Natural Science Foundation of China(Nos.31471810,31272081)the Major Science and Technology Program for Water Pollution Control and Treatment(No.2012ZX07101-013-05(02))the Jiangsu Key Technology R&D Program(No.BE2012372)
文摘The effects of light, temperature, and coculture on the intracellular microcystin-LR(MCLR) quota of M icrocystis aeruginosa were evaluated based on coculture experiments with nontoxic Dolichospermum( Anabaena) fl os- aquae. The MC-LR quota and transcription of m cy B and m cy D genes encoding MC synthetases in M. aeruginosa were evaluated on the basis of cell counts, high-performance liquid chromatography, and reverse-transcription quantitative real-time PCR. The MC-LR quotas of M. aeruginosa in coculture with a 1/1 ratio of inoculum of the two species were signifi cantly lower relative to monocultures 6-d after inoculation. Decreased MC-LR quotas under coculture conditions were enhanced by increasing the D. fl os- aquae to M. aeruginosa ratio in the inoculum and by environmental factors, such as temperature and light intensity. Moreover, the transcriptional concentrations of mcy B and mcy D genes in M. aeruginosa were signifi cantly inhibited by D. fl os- aquae competition in coculture(P <0.01), lowered to 20% of initial concentrations within 8 days. These data suggested that coculture effects by D. fl os- aquae not only reduced M. aeruginosa 's intracellular MC-LR quota via inhibition of genes encoding MC synthetases, but also that this effect was regulated by environmental factors, including temperature and light intensities.
基金Supported by Ecological Environment Construction and Protection Demonstration Project of Three Gorges~~
文摘[Objective] The aim was to explore the relationship between alage-lysing bacterium and Anabaena flosaquae so as to provide reference for the control of bloom. [Method] An algae-lysing bacterium strain named S7 was isolated from eu- trophic river. The lyric efficiency and performing mode of S7 strain to Anabaena flos- aquae was studied. Influence of different environmental factors and the relationship between S7 strain and Anabaena flosaquae was also studied, and then the bacteri- um strain was physiologically identified. [Result] More than 90% of Anabaena flos- aquae had been removed by 7 d when the volume ratio of medium to algae solu- tion was 30%, the pH was 9 and the temperature was 35 ℃. These results also showed that a mutual inhibit relationship existed between S7 strain and Anabaena flos-aquae. The S7 strain killed the algae by indirectly through certain lyric agents in absence of direct contact with the target but by secreting metabolites. Moreover, these lyric agents also had the thermostability. 16SrDNA sequence analysis showed that S7 strain belonged to Chryseobacterium sp. [Conclusion] The examined Poly-p proved that S7 strain is polyphosphate accumulating bacteria （PAOs） and has better lyric efficiency.
