The impact of cation concentration on Microcystis (cyanobacteria) scum formation

Cyanobacterial scums at the surface of the lakes are potentially harmful phenomena with increasing occurrence in the last decades, and the causes that lead to their formation are still an unresolved issue. In order to better understand what triggers the scums, we investigated the effect of several Mg²⁺ and Ca²⁺ ion concentrations in promoting them in eight Microcystis aeruginosa strains. The possibility to prevent scum formation by using the ion chelator EDTA was also explored. We found that in some strains the cell aggregation takes place under lower ion source concentrations (20 mM MgSO₄ or CaCl₂), while in others this phenomenon does not occur even at 60 mM concentration. The scum formation correlated to the amount of extracellular polymeric substances (between 234 and 351 µg/cell). EDTA failed to prevent the scum formation in most strains, and in turn it caused cell lysis followed by the release of cellular content into the culture medium. We emphasize the relevance of these results for cyanobacterial scum formation in the environment and we also suggest that controlling the salinity of the medium (by manipulating the ion concentration) is a potentially efficient method for biomass harvesting in large ponds/tanks

National Defence - Its Role and Importance in Ensuring the Image of a Stable State

By carrying out the national defence, national interests are protected by the active involvement of state institutions with responsibilities in the field, but not only these, being committed the available resources of the state in order to ensure the sovereignty, the independence, the unity, the territorial integrity and the constitutional democracy, under the conditions of combating any type of aggression. This is achieved through the full exercise of citizens' rights and freedoms, through conscious assumption of responsibilities, and by the affirming a state as an active member of the community and international organisations. The national defence is very well grounded, being regulated at national level by rules approved by the President of the country, by the Government, having the legal opinion of the Supreme Defence Council of the Country.One of the most important resources needed to achieve the national defence is the human resource that needs to be continuously prepared and trained through various forms of preparation. A high level human resource training determines a high level of a state national defence

Removal of a General – The Rebirth of a Latent Conflict Between Two Sovereign States: USA and Iran

Generally speaking, the relations between different states of the world, but especially between the states that represent world powers or have a certain type of arsenal, are able to influence the stability and the state of calmness from a certain region of the world, but also the notion of peace at the globally level. The 2020 year began with such a situation, in the sense that United States of America and Iran, which have been for a long period in relations not among the most well, have arrived at a moment that could represent, to a very large extent, the starting point of a conflict that will enter in the world history. The elimination of a very important Iranian general by US troops in early January 2020, by a surprise attack amonk Iraqian teritory, markedly aggravated relations between the United States of America and Iran, but also between the great world power and Iraq or other major global players who have harshly criticized the US attack

The impact of cation concentration on Microcystis (cyanobacteria) scum formation

Abstract Cyanobacterial scums at the surface of the lakes are potentially harmful phenomena with increasing occurrence in the last decades, and the causes that lead to their formation are still an unresolved issue. In order to better understand what triggers the scums, we investigated the effect of several Mg2+ and Ca2+ ion concentrations in promoting them in eight Microcystis aeruginosa strains. The possibility to prevent scum formation by using the ion chelator EDTA was also explored. We found that in some strains the cell aggregation takes place under lower ion source concentrations (20 mM MgSO4 or CaCl2), while in others this phenomenon does not occur even at 60 mM concentration. The scum formation correlated to the amount of extracellular polymeric substances (between 234 and 351 µg/cell). EDTA failed to prevent the scum formation in most strains, and in turn it caused cell lysis followed by the release of cellular content into the culture medium. We emphasize the relevance of these results for cyanobacterial scum formation in the environment and we also suggest that controlling the salinity of the medium (by manipulating the ion concentration) is a potentially efficient method for biomass harvesting in large ponds/tanks