| Abstract [eng] |
In recent years, there has been growing interest in rare earth compounds such as lanthanides. Lanthanides play a number of roles in a wide range of fields - including chemistry, biology, medicine and industry. Lanthanide compounds have become an essential part of many modern technologies, but the increased use of these compounds has also led to an increase in their release into the biosphere around us. Lanthanides are considered to be non-essential elements that can cause both positive and negative physiological reactions in living organisms. Unlike heavy metals, whose toxicity has been extensively studied, the effects of lanthanides, and in particular their effects on the aquatic environment related to the exploitation of lanthanides, have not been given sufficient attention so far. Haematococcus pluvialis is a unicellular freshwater green alga of the family Haematococcaceae, which has a distinct biphasic life cycle consisting of a vegetative phase and a dormant phase. During the dormant phase, under stressful conditions, this green alga synthesises the carotenoid astaxanthin, which protects the cell from ROS and sunlight. Astaxanthin is one of the strongest antioxidants and is therefore widely used in agriculture, medicine and biotechnological industry. The synthesis of astaxanthin in H. pluvialis cells is stimulated by stress conditions such as nutrient deficiency, pH, salinity and the presence of heavy metals in the medium. In this work, the effect of combinations of the rare earth element lanthanum, lanthanum nitrate and lanthanum chloride heptahydrate on HpR and HpŽ stage cultures was tested. The effects of different concentrations of lanthanum compounds on different H. pluvialis cultures were evaluated and it was observed that concentrations of lanthanum nitrate higher than 0.1 mol/L induced cell death in the medium, while concentrations lower than 0.05 mol/L induced biomass growth, but reduced astaxanthin synthesis. Concentrations of lanthanum chloride heptahydrate above 0,0027 mol/L were found to negatively affect biomass growth and astaxanthin synthesis in both HpR and HpŽ stages of H. pluvialis cultures. |
