Although many studies have found that cadmium(Cd)can be toxic to microalgae,only a few reports focused on the role of extracellular polymeric substances(EPS)in Cd(Ⅱ)detoxification.The biochemical and physiological en...Although many studies have found that cadmium(Cd)can be toxic to microalgae,only a few reports focused on the role of extracellular polymeric substances(EPS)in Cd(Ⅱ)detoxification.The biochemical and physiological endpoints of Microcystis aeruginosa,including the composition and functional groups of soluble EPS(SL-EPS),loosely bound EPS(LB-EPS),and tightly bound EPS(TB-EPS),were detected to elucidate the toxicity and detoxification mechanisms of Cd(Ⅱ)for cyanobacteria.Toxicological and physiological assays on M.aeruginosa showed that the 0.25-mg/L Cd(Ⅱ)resulted in a larger inhibition on growth and F_(v)/F_(m).Nevertheless,Cd(Ⅱ)significantly induced much higher contents of superoxide dismutase(SOD),intracellular microcystin LR(MC-LR),extracellular MC-LR,and EPS.Scanning electron microscopy with energy dispersive X-ray spectroscopy confirmed that Cd(Ⅱ)was absorbed into the EPS layer.Fourier transform infrared spectrum analysis revealed that the functional groups bound with Cd(Ⅱ)of algae biomass,SL-EPS,LB-EPS,and TB-EPS were somewhat different.The C=O/C=N groups ofδ-lactam or protein were their prominent functional groups,suggesting that amide or proteins in the EPS played a key role in the adsorption in Cd(Ⅱ).The concentration of 0.25 mg/L of Cd(Ⅱ)may change the chemical structure of EPS by altering the production of protein-like substances containing tryptophan.This study indicated that M.aeruginosa could detoxify Cd(Ⅱ)stress via induction of antioxidant capacity(higher SOD activity and MC synthesis),EPS production,and modification in chemical structure of EPS.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
Using allelochemicals to suppress cyanobacteria growth is a prospective method for its high efficiency and ecological safety.However,the suppression efficiency is affected inevitably by the extracellular polymeric sub...Using allelochemicals to suppress cyanobacteria growth is a prospective method for its high efficiency and ecological safety.However,the suppression efficiency is affected inevitably by the extracellular polymeric substances(EPS)produced by cyanobacteria,and the knowledge about the roles of EPS in resistance to allelochemical stress is scarce.For the study,two typical anti-cyanobacterial allelochemicals were adopted to investigate the role of EPS in resistance to allelochemical stress on Microcystis aeruginosa.Results show that EPS was crucial in alleviating the toxicity of allelochemicals to algae,especially in stabilizing the metabolism and photosynthetic activity of algal cells.The aggregation rate of algal cells increased with the increase of EPS secretion,which alleviated the stress of allelopathy.Tryptophan proteins and humic acids in EPS provided a binding site for allelochemicals,and the EPS-allelochemicals complex were formed by chemical bonding.This study improved our comprehension of the role of EPS in algal inhibition by allelochemicals.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 study aimed to discuss the effects of pH value on the growth metabolism of Microcystis aeruginosa and the phosphorus metabolism relationship with adnascent Pseudomonas.[Method] By the phosphorus uptake...[Objective] The study aimed to discuss the effects of pH value on the growth metabolism of Microcystis aeruginosa and the phosphorus metabolism relationship with adnascent Pseudomonas.[Method] By the phosphorus uptake experiment of M.aeruginosa under different pH conditions(8.0-10.0) and the effect experiment on the phosphorus metabolism of M.aeruginosa and adnascent Pseudomonas under different pH conditions(7.0-9.0),the phosphorus uptake of M.aeruginosa in the short time and the growth curve of M.aeruginosa,the change of phosphorus concentration in the water,the change of total phosphorus content in M.aeruginosa in the longer time were measured.[Results] In the short time,pH value had the effects on the absorption phosphorus ability of M.aeruginosa.As pH value rose,the absorption phosphorus ability enhanced.During the longer time,the higher pH value was,the quicker the growth speed of M.aeruginosa was,and the better the growth situation was.M.aeruginosa had the ability of self regulation pH value and could use the phosphorus well in the water which was released from Pseudomonas.In the system of the algae,bacteria and water,the phosphorus in the bacteria played the role of phosphorus source which was released slowly.Though the phosphorus concentration was lower,it was favorable to the growth of algae.[Conclusions] pH value was the factor that affected the circle of the phosphorus element in the system of algae-bacteria-water.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.31800457,32170383)。
文摘Although many studies have found that cadmium(Cd)can be toxic to microalgae,only a few reports focused on the role of extracellular polymeric substances(EPS)in Cd(Ⅱ)detoxification.The biochemical and physiological endpoints of Microcystis aeruginosa,including the composition and functional groups of soluble EPS(SL-EPS),loosely bound EPS(LB-EPS),and tightly bound EPS(TB-EPS),were detected to elucidate the toxicity and detoxification mechanisms of Cd(Ⅱ)for cyanobacteria.Toxicological and physiological assays on M.aeruginosa showed that the 0.25-mg/L Cd(Ⅱ)resulted in a larger inhibition on growth and F_(v)/F_(m).Nevertheless,Cd(Ⅱ)significantly induced much higher contents of superoxide dismutase(SOD),intracellular microcystin LR(MC-LR),extracellular MC-LR,and EPS.Scanning electron microscopy with energy dispersive X-ray spectroscopy confirmed that Cd(Ⅱ)was absorbed into the EPS layer.Fourier transform infrared spectrum analysis revealed that the functional groups bound with Cd(Ⅱ)of algae biomass,SL-EPS,LB-EPS,and TB-EPS were somewhat different.The C=O/C=N groups ofδ-lactam or protein were their prominent functional groups,suggesting that amide or proteins in the EPS played a key role in the adsorption in Cd(Ⅱ).The concentration of 0.25 mg/L of Cd(Ⅱ)may change the chemical structure of EPS by altering the production of protein-like substances containing tryptophan.This study indicated that M.aeruginosa could detoxify Cd(Ⅱ)stress via induction of antioxidant capacity(higher SOD activity and MC synthesis),EPS production,and modification in chemical structure of EPS.
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.51979137,51779079,41931292)。
文摘Using allelochemicals to suppress cyanobacteria growth is a prospective method for its high efficiency and ecological safety.However,the suppression efficiency is affected inevitably by the extracellular polymeric substances(EPS)produced by cyanobacteria,and the knowledge about the roles of EPS in resistance to allelochemical stress is scarce.For the study,two typical anti-cyanobacterial allelochemicals were adopted to investigate the role of EPS in resistance to allelochemical stress on Microcystis aeruginosa.Results show that EPS was crucial in alleviating the toxicity of allelochemicals to algae,especially in stabilizing the metabolism and photosynthetic activity of algal cells.The aggregation rate of algal cells increased with the increase of EPS secretion,which alleviated the stress of allelopathy.Tryptophan proteins and humic acids in EPS provided a binding site for allelochemicals,and the EPS-allelochemicals complex were formed by chemical bonding.This study improved our comprehension of the role of EPS in algal inhibition by allelochemicals.
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"973"Project(2008CB418003)The National Natural Science Fund(30700414)
文摘[Objective] The study aimed to discuss the effects of pH value on the growth metabolism of Microcystis aeruginosa and the phosphorus metabolism relationship with adnascent Pseudomonas.[Method] By the phosphorus uptake experiment of M.aeruginosa under different pH conditions(8.0-10.0) and the effect experiment on the phosphorus metabolism of M.aeruginosa and adnascent Pseudomonas under different pH conditions(7.0-9.0),the phosphorus uptake of M.aeruginosa in the short time and the growth curve of M.aeruginosa,the change of phosphorus concentration in the water,the change of total phosphorus content in M.aeruginosa in the longer time were measured.[Results] In the short time,pH value had the effects on the absorption phosphorus ability of M.aeruginosa.As pH value rose,the absorption phosphorus ability enhanced.During the longer time,the higher pH value was,the quicker the growth speed of M.aeruginosa was,and the better the growth situation was.M.aeruginosa had the ability of self regulation pH value and could use the phosphorus well in the water which was released from Pseudomonas.In the system of the algae,bacteria and water,the phosphorus in the bacteria played the role of phosphorus source which was released slowly.Though the phosphorus concentration was lower,it was favorable to the growth of algae.[Conclusions] pH value was the factor that affected the circle of the phosphorus element in the system of algae-bacteria-water.
