Objective To isolate and characterize indigenous algicidal bacteria and their algae-lysing compounds active against Microcystis aeruginosa, strains TH1, TH2, and FACHB 905. Methods The bacteria were identified using t...Objective To isolate and characterize indigenous algicidal bacteria and their algae-lysing compounds active against Microcystis aeruginosa, strains TH1, TH2, and FACHB 905. Methods The bacteria were identified using the Biolog automated microbial identification system and 16S rDNA sequence analysis. The algae-lysing compounds were isolated and purified by silica gel column chromatography and reverse-phase high performance liquid chromatography. Their structures were confirmed by Nuclear Magnetic Resonance （NMR） and Fourier Transform infrared （FT-IR） spectroscopy. Algae-lysing activity was observed using microscopy. Results The algae-lysing bacterium LTH-2 isolated from Lake Taihu was identified as Serratia marcescens. Strain LTH-2 secreted a red pigment identified as prodigiosin （C20H25N30）, which showed strong lytic activity with algal strains M. aeruginoso TH1, TH2, and FACHB 905 in a concentration-dependent manner. The 50% inhibitory concentration （ICs0） of prodigiosin with the algal strains was 4.8 （±0.4）×10^-2 μg/mL, 8.9 （±1.1）×10^-2μg/mL, and 1.7 （±0.1）×10^-1 μg/mL in 24 h, respectively. Conclusion The bacterium LTH-2 and its pigment related to damage of cell membranes. The bacterium for regulating blooms of harmful M. aeruginosa. had strong Microcystis-lysing activity probably LTH-2 and its red pigment are potentially useful展开更多
While many harmful algal blooms have been associated with increasing eutrophication, not all species respond similarly and the increasing challenge, especially for resource managers, is to determine which blooms are r...While many harmful algal blooms have been associated with increasing eutrophication, not all species respond similarly and the increasing challenge, especially for resource managers, is to determine which blooms are related to eutrophication and to understand why particular species proliferate under specific nutrient conditions. The overall goal of this brief review is to describe why nutrient loads are not changing in stoichiometric proportion to the "Redfield ratio", and why this has important consequences for algal growth. Many types of harmful algae appear to be able to thrive, and/or increase their production of toxins, when nutrient loads are not in proportion classically identified as Redfield ratios. Here we also describe some of the physiological mechanisms of different species to take up nutrients and to thrive under conditions of nutrient imbalance.展开更多
Three mesocosm experiments were conducted in the East China Sea during blooms of Prorocentrum donghaiense Lu in May of 1998,2002 and 2003 to examine the role of nutrients in the formation of these harmful algae blooms...Three mesocosm experiments were conducted in the East China Sea during blooms of Prorocentrum donghaiense Lu in May of 1998,2002 and 2003 to examine the role of nutrients in the formation of these harmful algae blooms（HABs）.The results showed that there was interspecies competition between P.donghaiense and Skeletonema costatum（Grev.） Cleve.The cell number of P.donghaiense and S.costatum accounted for about 85% and 11% of the total cell number of phytoplankton respectively at the beginning of the experiment in May 1998.In May 2002,at the beginning of the experiment,the cell number of P.donghaiense accounted for 55%-66% of the total and S.costatum accounted for 32%-42%.The density of P.donghaiense and S.costatum was over 95% and 1%-5% respectively in May 2003.The results of these three mesocosm experiments showed that the dominant species in this specific community varied with different nutrient availability.Under low-phosphate conditions,the dominant species was P.donghaiense,while S.costatum became dominant in phosphate-replete cases.The average growth rate（1.08 d-1） of S.costatum in exponential growth phase was higher than that（0.39 d-1） of P.donghaiense.In the mesocosm,S.costatum predominated in the mesocosm by its rapid growth.When phosphorus was depleted,the cell number of S.costatum dropped rapidly,while P.donghaiense Lu decreased more slowly.The results from mesocosm experiment may explain why：（1） P.donghaiense bloom usually occurs in May,when phosphate concentration is low;（2） the bloom of S.costatum appears in early spring and summer time,when nutrients increase with increasing Changjiang River（Yangtze River） runoff;（3） the bloom of S.costatum is short and that of P.donghaiense Lu can last more than a month in the East China Sea.展开更多
Harmful algal blooms (HABs) are a serious worldwide issue which has posed great risks on marine ecosystems and public health by directly releasing toxins or indirectly leading to anoxia in marine environment. In recen...Harmful algal blooms (HABs) are a serious worldwide issue which has posed great risks on marine ecosystems and public health by directly releasing toxins or indirectly leading to anoxia in marine environment. In recent years HABs have caused huge economic losses in China, particularly in the Yangtze Estuary and the adjacent East China Sea (ECS). The present study investigated the spatial-temporal and species characteristics of large-scale HABs in this area using geographic information system (GIS) Kernel Density Estimation (KDE) spatial analysis, statistical methods and satellite image interpretation. Results revealed that the Yangtze Estuary, Zhoushan island, Xiangshan bay and Jiushan island are the regions with highest frequency of large-scale HABs. HABs in the ECS reached a peak in terms of total number and area in 2003 to 2005 and occupied a high percentage (around 70% in area and 60% in occurrence) in the four Chinese coastal waters. The number of large-scale HABs (> 1000 km2) in the Yangtze Estuary and the adjacent ECS declined after 2005 while that of HABs (> 100 km2) declined after 2008. Large-scale HABs occurrences concentrated in summer (May to July), and the averaged duration increased continually from the shortest time (1.3 days) in 2001 to the longest (10.9 days) in 2010 for each HAB. 17 causative species were found with Prorocentrum dentutam as the most frequent dominant species, followed by Skeletonema costatum, Karenia mikimotoi, and Chaetoceros curvisetus. Water discoloration observed in MODIS satellite true color images was well consistent with the corresponding HABs reported by State Oceanic Administration of China (SOA). Multiple factors involving eutrophication, physical dynamics, topography and deposition conditions contributed to the formation of frequent HABs in the ECS. Three strategies including establishing a synthesized system, improving the previous database and investigating multiple contributors were proposed for future HABs monitoring and management.展开更多
基金supported by the National Science and Technology Major Project (2012ZX07101-005)the National Natural Science Foundation of China (30972440)Jiangsu Province Postgraduate Innovation Project (CX10B-087Z)
文摘Objective To isolate and characterize indigenous algicidal bacteria and their algae-lysing compounds active against Microcystis aeruginosa, strains TH1, TH2, and FACHB 905. Methods The bacteria were identified using the Biolog automated microbial identification system and 16S rDNA sequence analysis. The algae-lysing compounds were isolated and purified by silica gel column chromatography and reverse-phase high performance liquid chromatography. Their structures were confirmed by Nuclear Magnetic Resonance （NMR） and Fourier Transform infrared （FT-IR） spectroscopy. Algae-lysing activity was observed using microscopy. Results The algae-lysing bacterium LTH-2 isolated from Lake Taihu was identified as Serratia marcescens. Strain LTH-2 secreted a red pigment identified as prodigiosin （C20H25N30）, which showed strong lytic activity with algal strains M. aeruginoso TH1, TH2, and FACHB 905 in a concentration-dependent manner. The 50% inhibitory concentration （ICs0） of prodigiosin with the algal strains was 4.8 （±0.4）×10^-2 μg/mL, 8.9 （±1.1）×10^-2μg/mL, and 1.7 （±0.1）×10^-1 μg/mL in 24 h, respectively. Conclusion The bacterium LTH-2 and its pigment related to damage of cell membranes. The bacterium for regulating blooms of harmful M. aeruginosa. had strong Microcystis-lysing activity probably LTH-2 and its red pigment are potentially useful
文摘While many harmful algal blooms have been associated with increasing eutrophication, not all species respond similarly and the increasing challenge, especially for resource managers, is to determine which blooms are related to eutrophication and to understand why particular species proliferate under specific nutrient conditions. The overall goal of this brief review is to describe why nutrient loads are not changing in stoichiometric proportion to the "Redfield ratio", and why this has important consequences for algal growth. Many types of harmful algae appear to be able to thrive, and/or increase their production of toxins, when nutrient loads are not in proportion classically identified as Redfield ratios. Here we also describe some of the physiological mechanisms of different species to take up nutrients and to thrive under conditions of nutrient imbalance.
基金The National Natural Science Foundation of China under contract Nos 40490262 and 3730114the CEOHAB Research Project of Na-tional Key Basic Research Development Program("973") of China under contract No. 2001CB409700
文摘Three mesocosm experiments were conducted in the East China Sea during blooms of Prorocentrum donghaiense Lu in May of 1998,2002 and 2003 to examine the role of nutrients in the formation of these harmful algae blooms（HABs）.The results showed that there was interspecies competition between P.donghaiense and Skeletonema costatum（Grev.） Cleve.The cell number of P.donghaiense and S.costatum accounted for about 85% and 11% of the total cell number of phytoplankton respectively at the beginning of the experiment in May 1998.In May 2002,at the beginning of the experiment,the cell number of P.donghaiense accounted for 55%-66% of the total and S.costatum accounted for 32%-42%.The density of P.donghaiense and S.costatum was over 95% and 1%-5% respectively in May 2003.The results of these three mesocosm experiments showed that the dominant species in this specific community varied with different nutrient availability.Under low-phosphate conditions,the dominant species was P.donghaiense,while S.costatum became dominant in phosphate-replete cases.The average growth rate（1.08 d-1） of S.costatum in exponential growth phase was higher than that（0.39 d-1） of P.donghaiense.In the mesocosm,S.costatum predominated in the mesocosm by its rapid growth.When phosphorus was depleted,the cell number of S.costatum dropped rapidly,while P.donghaiense Lu decreased more slowly.The results from mesocosm experiment may explain why：（1） P.donghaiense bloom usually occurs in May,when phosphate concentration is low;（2） the bloom of S.costatum appears in early spring and summer time,when nutrients increase with increasing Changjiang River（Yangtze River） runoff;（3） the bloom of S.costatum is short and that of P.donghaiense Lu can last more than a month in the East China Sea.
文摘Harmful algal blooms (HABs) are a serious worldwide issue which has posed great risks on marine ecosystems and public health by directly releasing toxins or indirectly leading to anoxia in marine environment. In recent years HABs have caused huge economic losses in China, particularly in the Yangtze Estuary and the adjacent East China Sea (ECS). The present study investigated the spatial-temporal and species characteristics of large-scale HABs in this area using geographic information system (GIS) Kernel Density Estimation (KDE) spatial analysis, statistical methods and satellite image interpretation. Results revealed that the Yangtze Estuary, Zhoushan island, Xiangshan bay and Jiushan island are the regions with highest frequency of large-scale HABs. HABs in the ECS reached a peak in terms of total number and area in 2003 to 2005 and occupied a high percentage (around 70% in area and 60% in occurrence) in the four Chinese coastal waters. The number of large-scale HABs (> 1000 km2) in the Yangtze Estuary and the adjacent ECS declined after 2005 while that of HABs (> 100 km2) declined after 2008. Large-scale HABs occurrences concentrated in summer (May to July), and the averaged duration increased continually from the shortest time (1.3 days) in 2001 to the longest (10.9 days) in 2010 for each HAB. 17 causative species were found with Prorocentrum dentutam as the most frequent dominant species, followed by Skeletonema costatum, Karenia mikimotoi, and Chaetoceros curvisetus. Water discoloration observed in MODIS satellite true color images was well consistent with the corresponding HABs reported by State Oceanic Administration of China (SOA). Multiple factors involving eutrophication, physical dynamics, topography and deposition conditions contributed to the formation of frequent HABs in the ECS. Three strategies including establishing a synthesized system, improving the previous database and investigating multiple contributors were proposed for future HABs monitoring and management.
