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
Twenty water bodies in China were sampled,and 186 strains of different Microcystis species were isolated,from which eight morpho species were identified and 43 stains containing the mcyB gene were detected.Phylogeneti...Twenty water bodies in China were sampled,and 186 strains of different Microcystis species were isolated,from which eight morpho species were identified and 43 stains containing the mcyB gene were detected.Phylogenetic analysis based on the mcyB gene indicated that the microcystin(MC)-producing Microcystis in China could be divided into two groups(ⅠandⅡ)and showed significant differences between the two groups.The maximum sequence similarity was 69.1%.Microcystins(MCs)were measured by high-performance liquid chromatography(HPLC)analysis,and no microcystin-RR(MC-RR)was detected in some strains belonging to GroupⅡ.Compared to other regions of the world,the proportion of Chinese MC-producing was different,and the regional differences were more obvious.A whole-cell polymerase chain reactio(PCR)assay was conducted to analyze the proportion of the mcyB gene in the laboratory cultured and field cultured Microcystis.The proportion of four morphospecies(M.vividis,M.ichthyoblabe,M.novacekii,and M.aeruginosa)that contained the mcyB gene exceeded 50%in the field cultured sample s.Compared with former studies,M.aeruginosa was the mo st likely morphotype that can produce MCs in the world.This study provided new insight of Microcystis hazard assessment and field monitoring.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
[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
[Objective]The relationship between signal molecule N-acety-homoserine lactones（AHLs） and Microcystis aeruginosa cell apoptosis was studied.[Method]With M.aeruginosa as the test materials treated by 5 μmol/L N-acet...[Objective]The relationship between signal molecule N-acety-homoserine lactones（AHLs） and Microcystis aeruginosa cell apoptosis was studied.[Method]With M.aeruginosa as the test materials treated by 5 μmol/L N-acety-homoserine lactones（AHLs）,the morphology of cell apoptosis was observed through staining with DAPI.[Result]Microcystis aeruginosa cell apoptosis was induced by signal molecule N-acetyhomoserine lactones（AHLs） with the concentration of 1 μmol/L to inhibit the growth and proliferation of Microcystis aeruginosa.[Conclusion] The results provided the important scientific basis and new management ideas for the treatment of water bloom of Microcystis aeruginosa.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the Science and Technology Project of Henan Province(Nos.19A180018,192102310306)the Key Laboratory of Algal Biology,Institute of Hydrobiology,Chinese Academy of Sciences(No.2018001)。
文摘Twenty water bodies in China were sampled,and 186 strains of different Microcystis species were isolated,from which eight morpho species were identified and 43 stains containing the mcyB gene were detected.Phylogenetic analysis based on the mcyB gene indicated that the microcystin(MC)-producing Microcystis in China could be divided into two groups(ⅠandⅡ)and showed significant differences between the two groups.The maximum sequence similarity was 69.1%.Microcystins(MCs)were measured by high-performance liquid chromatography(HPLC)analysis,and no microcystin-RR(MC-RR)was detected in some strains belonging to GroupⅡ.Compared to other regions of the world,the proportion of Chinese MC-producing was different,and the regional differences were more obvious.A whole-cell polymerase chain reactio(PCR)assay was conducted to analyze the proportion of the mcyB gene in the laboratory cultured and field cultured Microcystis.The proportion of four morphospecies(M.vividis,M.ichthyoblabe,M.novacekii,and M.aeruginosa)that contained the mcyB gene exceeded 50%in the field cultured sample s.Compared with former studies,M.aeruginosa was the mo st likely morphotype that can produce MCs in the world.This study provided new insight of Microcystis hazard assessment and field monitoring.
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"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.
基金Supported by National Natural Science Fund(30960036)Key Schoollevel Project of Kunming University(20091016)~~
文摘[Objective]The relationship between signal molecule N-acety-homoserine lactones（AHLs） and Microcystis aeruginosa cell apoptosis was studied.[Method]With M.aeruginosa as the test materials treated by 5 μmol/L N-acety-homoserine lactones（AHLs）,the morphology of cell apoptosis was observed through staining with DAPI.[Result]Microcystis aeruginosa cell apoptosis was induced by signal molecule N-acetyhomoserine lactones（AHLs） with the concentration of 1 μmol/L to inhibit the growth and proliferation of Microcystis aeruginosa.[Conclusion] The results provided the important scientific basis and new management ideas for the treatment of water bloom of Microcystis aeruginosa.
