INVESTIGADORES
WUNDERLIN Daniel Alberto
artículos
Título:
Effect of Iron, Ammonium and Temperature on Microcystins Content by a Natural Concentrated Microcystis aeruginosa.PopulationPopulation.
Autor/es:
AMÉ, M.V.; WUNDERLIN, D. A.
Revista:
WATER AIR AND SOIL POLLUTION
Editorial:
SPRINGER
Referencias:
Año: 2005 vol. 168 p. 235 - 248
ISSN:
0049-6979
Resumen:
We report results of a study conducted to evaluate effects of ammonium, iron and temperature on microcystins (MC) and proteins content in cultures of a natural Microcystis aeruginosaMicrocystis aeruginosa population, concentrated from a field sample of San Roque reservoir (C´ordoba – Argentina). Based on a previous field study, we tested two temperatures (20 and 28 .C), two iron concentrations (1µMand 10µM) and two ammonium-nitrogen conditions (absence and 54µM) in semi-continuous cultures. Total MC (TMC = MC-LR + MC-RR) and protein content per cyanobacteria cell increased when Fe concentration was enlarged. However, the ratio TMC: protein was almost the same for both iron concentrations. Thus, a high level of iron enhances both protein andMCcontent in the same proportion. TMC and protein content are significantly lowered in presence of 54µM-N-ammonium. Additionally, the ratio TMC: protein is lowered by almost two folds in cultures having ammonium. Increasing the temperature does not affect the protein content or TMC per cell. However, cultures carried out at 28 .C maintain the same MC-LR: MC-RR ratio during all the studied period, while cultures developed at 20 .C show that MC-RR content is increased by 82-fold after four growth cycles (20 days total), while MC-LR remain almost constant in the same time. As a result, in our case, different temperatures produce a significant change in the pattern of MC content but not in the content of TMC per cell. The two-fold drop observed inMCcontent in presence of ammonium are within the range expected for physiological responses of cyanobacteria, raising questions on the probable inhibitory role of ammonium in MC production. On the contrary, the 82-fold increase of MC-RR observed at 20 .C exceed the effects attributable to a cell physiological response, and could be better explained by an ecological shift from the starting genotype composition. Metagenomics, or similar molecular techniques, would provide the necessary tools to elucidate the ecological effect of temperature on cyanobacteria populations..C), two iron concentrations (1µMand 10µM) and two ammonium-nitrogen conditions (absence and 54µM) in semi-continuous cultures. Total MC (TMC = MC-LR + MC-RR) and protein content per cyanobacteria cell increased when Fe concentration was enlarged. However, the ratio TMC: protein was almost the same for both iron concentrations. Thus, a high level of iron enhances both protein andMCcontent in the same proportion. TMC and protein content are significantly lowered in presence of 54µM-N-ammonium. Additionally, the ratio TMC: protein is lowered by almost two folds in cultures having ammonium. Increasing the temperature does not affect the protein content or TMC per cell. However, cultures carried out at 28 .C maintain the same MC-LR: MC-RR ratio during all the studied period, while cultures developed at 20 .C show that MC-RR content is increased by 82-fold after four growth cycles (20 days total), while MC-LR remain almost constant in the same time. As a result, in our case, different temperatures produce a significant change in the pattern of MC content but not in the content of TMC per cell. The two-fold drop observed inMCcontent in presence of ammonium are within the range expected for physiological responses of cyanobacteria, raising questions on the probable inhibitory role of ammonium in MC production. On the contrary, the 82-fold increase of MC-RR observed at 20 .C exceed the effects attributable to a cell physiological response, and could be better explained by an ecological shift from the starting genotype composition. Metagenomics, or similar molecular techniques, would provide the necessary tools to elucidate the ecological effect of temperature on cyanobacteria populations.µMand 10µM) and two ammonium-nitrogen conditions (absence and 54µM) in semi-continuous cultures. Total MC (TMC = MC-LR + MC-RR) and protein content per cyanobacteria cell increased when Fe concentration was enlarged. However, the ratio TMC: protein was almost the same for both iron concentrations. Thus, a high level of iron enhances both protein andMCcontent in the same proportion. TMC and protein content are significantly lowered in presence of 54µM-N-ammonium. Additionally, the ratio TMC: protein is lowered by almost two folds in cultures having ammonium. Increasing the temperature does not affect the protein content or TMC per cell. However, cultures carried out at 28 .C maintain the same MC-LR: MC-RR ratio during all the studied period, while cultures developed at 20 .C show that MC-RR content is increased by 82-fold after four growth cycles (20 days total), while MC-LR remain almost constant in the same time. As a result, in our case, different temperatures produce a significant change in the pattern of MC content but not in the content of TMC per cell. The two-fold drop observed inMCcontent in presence of ammonium are within the range expected for physiological responses of cyanobacteria, raising questions on the probable inhibitory role of ammonium in MC production. On the contrary, the 82-fold increase of MC-RR observed at 20 .C exceed the effects attributable to a cell physiological response, and could be better explained by an ecological shift from the starting genotype composition. Metagenomics, or similar molecular techniques, would provide the necessary tools to elucidate the ecological effect of temperature on cyanobacteria populations.= MC-LR + MC-RR) and protein content per cyanobacteria cell increased when Fe concentration was enlarged. However, the ratio TMC: protein was almost the same for both iron concentrations. Thus, a high level of iron enhances both protein andMCcontent in the same proportion. TMC and protein content are significantly lowered in presence of 54µM-N-ammonium. Additionally, the ratio TMC: protein is lowered by almost two folds in cultures having ammonium. Increasing the temperature does not affect the protein content or TMC per cell. However, cultures carried out at 28 .C maintain the same MC-LR: MC-RR ratio during all the studied period, while cultures developed at 20 .C show that MC-RR content is increased by 82-fold after four growth cycles (20 days total), while MC-LR remain almost constant in the same time. As a result, in our case, different temperatures produce a significant change in the pattern of MC content but not in the content of TMC per cell. The two-fold drop observed inMCcontent in presence of ammonium are within the range expected for physiological responses of cyanobacteria, raising questions on the probable inhibitory role of ammonium in MC production. On the contrary, the 82-fold increase of MC-RR observed at 20 .C exceed the effects attributable to a cell physiological response, and could be better explained by an ecological shift from the starting genotype composition. Metagenomics, or similar molecular techniques, would provide the necessary tools to elucidate the ecological effect of temperature on cyanobacteria populations.µM-N-ammonium. Additionally, the ratio TMC: protein is lowered by almost two folds in cultures having ammonium. Increasing the temperature does not affect the protein content or TMC per cell. However, cultures carried out at 28 .C maintain the same MC-LR: MC-RR ratio during all the studied period, while cultures developed at 20 .C show that MC-RR content is increased by 82-fold after four growth cycles (20 days total), while MC-LR remain almost constant in the same time. As a result, in our case, different temperatures produce a significant change in the pattern of MC content but not in the content of TMC per cell. The two-fold drop observed inMCcontent in presence of ammonium are within the range expected for physiological responses of cyanobacteria, raising questions on the probable inhibitory role of ammonium in MC production. On the contrary, the 82-fold increase of MC-RR observed at 20 .C exceed the effects attributable to a cell physiological response, and could be better explained by an ecological shift from the starting genotype composition. Metagenomics, or similar molecular techniques, would provide the necessary tools to elucidate the ecological effect of temperature on cyanobacteria populations..C maintain the same MC-LR: MC-RR ratio during all the studied period, while cultures developed at 20 .C show that MC-RR content is increased by 82-fold after four growth cycles (20 days total), while MC-LR remain almost constant in the same time. As a result, in our case, different temperatures produce a significant change in the pattern of MC content but not in the content of TMC per cell. The two-fold drop observed inMCcontent in presence of ammonium are within the range expected for physiological responses of cyanobacteria, raising questions on the probable inhibitory role of ammonium in MC production. On the contrary, the 82-fold increase of MC-RR observed at 20 .C exceed the effects attributable to a cell physiological response, and could be better explained by an ecological shift from the starting genotype composition. Metagenomics, or similar molecular techniques, would provide the necessary tools to elucidate the ecological effect of temperature on cyanobacteria populations..C show that MC-RR content is increased by 82-fold after four growth cycles (20 days total), while MC-LR remain almost constant in the same time. As a result, in our case, different temperatures produce a significant change in the pattern of MC content but not in the content of TMC per cell. The two-fold drop observed inMCcontent in presence of ammonium are within the range expected for physiological responses of cyanobacteria, raising questions on the probable inhibitory role of ammonium in MC production. On the contrary, the 82-fold increase of MC-RR observed at 20 .C exceed the effects attributable to a cell physiological response, and could be better explained by an ecological shift from the starting genotype composition. Metagenomics, or similar molecular techniques, would provide the necessary tools to elucidate the ecological effect of temperature on cyanobacteria populations..C exceed the effects attributable to a cell physiological response, and could be better explained by an ecological shift from the starting genotype composition. Metagenomics, or similar molecular techniques, would provide the necessary tools to elucidate the ecological effect of temperature on cyanobacteria populations.