Cultivation of Dunaliella salina Microalgae in the Nutrient Medium from Neutral-Sulfite Alkalis

Abstract

The effectiveness of cultivation of microalgae Dunaliella salina in the nutrient medium from neutral-sulfite alkalis obtained during the production of cellulose from birch wood, with additional sodium chloride addition was established. D. salina microalgae were isolated from the bottom sediment of the Koyash Lake of the Kerch Peninsula. It was shown that the physiological activity of microalgae was affected by the amount of sodium chloride introduced into the nutrient medium. When up to 5 % sodium chloride is added to the nutrient medium. D. salina microalgae exhibit halotolerant properties when up to 5 % of sodium chloride is added to the nutrient medium. With an increase in the amount of sodium chloride introduced up to 30 %, D. salina culture exhibits halophilic properties. The best kinetic characteristics of the growth of D. salina when cultivated in the nutrient medium from neutral sulfite alkalis were observed at halophilic physiological activity. The yield of biomass of D. salina microalgae when cultivated in the nutrient medium without and when 5 % sodium chloride was added to the nutrient medium from neutral-sulfite alkalis is higher compared to the addition of 15 and 30 % sodium chloride to the nutrient medium. However, the accumulation of protein has an opposite dependence, in particular, the protein content of the culture fluid, in which 15 and 30 % sodium chloride was applied is higher than that when 5 % sodium chloride was applied. With an increase in the duration of cultivation up to 240 hours, a decrease in the pH of the nutrient medium from 7.04 to 4.70 was observed, this was due to the assimilation by microalgae of mineral and organic-bound nitrogen present in the nutrient medium from neutral-sulfite alkalis. It was established that during cultivation microalgae assimilate both reducing substances and coloring substances present in the nutrient medium, which results in intensive cell growth. With an increase in the duration of cultivation of microalgae, an increase in the number of cells in the culture fluid to 4 ⋅ 106 cl/ml was observed, which at the same time synthesize the extracellular enzyme xylanase, which contributes to the additional formation of reducing substances in the nutrient medium due to the enzymatic hydrolysis of xylan. The obtained research results show the prospects of using neutral-sulfite alkalis in biotechnology in the cultivation of D. salina microalgae for the production of biological products. For citation: Iksanov R.A., Kanarsky A.V., Kanarskaya Z.A., Gеmatdinova V.M. Cultivation of Dunaliella salina Microalgae in the Nutrient Medium from Neutral-Sulfite Alkalis. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 6, pp. 162–175. (In Russ.). https://doi.org/10.37482/0536-1036-2023-6-162-175