ORIGINAL ARTICLE

Peculiarities of the Growth and Photosynthetic Pigments Content in Algaeculture of Acutodesmus dimorphus (Tupin) P.M. Tsarenko under Salt and Acetate Stresses

The objective of this research was to investigate the effect of salt (NaCl) and acetate (NaC₂H₃O₂) stresses on the pattern of biomass accumulation and photosynthetic pigments content in algae culture of the freshwater green alga Acutodesmus dimorphus (Turpin) P.M. Tsarenko IBASU-A 251. We demonstrated that sodium chloride introduced in a culture medium at various concentrations caused a gradual reduction of the microalga biomass whose maximum was recorded at the salt concentration of 1.5%. Addition of sodium acetate at the same concentrations led, on the contrary, to a sharp (more than two times) decrease of A. dimorphus biomass. On the 18^th day of culturing under salt stress conditions the chlorophyll a content decreased 1.5-2.5 times, the chlorophyll b content – 1.3-1.7 times, while the carotenoids quantity increased 1.2-1.6 times. Under acetate stress conditions the chlorophyll a content decreased 2-3 times, that of chlorophyll b – 1.7 – 1.8 times whereas the carotenoids quantity increased within the range of 1.4-1.8 times. Increase in chemical stressors concentrations involved some reduction of the chlorophylls а/b ratio and total chlorophylls а+b content, and at the same time, the ratio carotenoids/a+b increased. Sodium acetate appeared to be a more powerful inducer of carotinogenesis than sodium chloride. The highest quantity of carotenoids was registered at 1% and 1.5% concentrations of NaC₂H₃O₂ in the culture medium and 0.75% concentration of NaCl. The results obtained enable to regard Acutodesmus dimorphus (Turpin) P.M. Tsarenko IBASU-A 251 as an active carotenoids producer to be later applied in studies of hypersynthesis of individual classes of this pigment.