The Effect of Sodium Chloride on Biomass Growth and Protein Synthesis during Cultivation of Dunaliella salina Microalgae on a Nutrient Medium from Beet Molasses

Abstract

Introduction. Currently, the applications of halophiles of the genus Halobacteriaceae are mainly limited to the use of β-carotene and hydrolases in the food and cosmetic industries. The expansion of halophile applications in biotechnology is based on the synthesis of effective and highly specific biocatalysts that can meet industrial needs. Halophiles are excellent sources of enzymes that are not only resistant to salt, but can also be effective in other extreme conditions.  The resistance of halophiles to external factors is of increasing interest to them from biotechnologists, because they are the source of many BAS, and their habitat allows cultivation in non-sterile conditions. In this regard, it is of scientific and practical interest to determine the possibility of using D. salina bacteria in industry, which are recommended for wastewater treatment, expression of recombinant proteins, production of biofuels, production of natural polymer materials.Purpose. To study the effectiveness of cultivation of microalgae Dunaliella salina (D. salina) on a nutrient medium from molasses, experiments with additional addition of sodium chloride were carried out in this work.Materials and Methods. The review includes foreign articles published in English for the period 2010-2023. Search for scientific articles on suitable topics in the bibliographic databases Google Scholar, Scopus, Web of Science. When selecting publications for review, priority was given to highly cited sourcesResults. It was found that an increase in the cultivation temperature of microalgae from 5 to 25℃ favorably affects the growth characteristics of D. Salina culture: the specific growth rate increases, and the cell generation time decreases. When the content of sodium chloride in the nutrient medium is up to 5%, D. salina microalgae exhibit halotolerant properties. With an increase in the NaCl content in the nutrient medium up to 30%, D. salina culture exhibits halophilic properties. The best kinetic characteristics of the growth of D. salina culture are manifested with halophilic physiological activity. The yield of biomass of D. salina microalgae during cultivation on a nutrient medium without application and when introducing 5% sodium chloride into the nutrient medium from molasses is higher compared to the introduction of 15 and 30% sodium chloride into the nutrient medium. According to the results obtained, it can be said that an increase in the content of sodium chloride leads to an increase in the growth rate of the culture and the generation time, also in the values of 30% NaCl, a higher content of protein and β-fructosidase is manifested. With an increase in the duration of cultivation up to 240 h, a decrease in the pH of the nutrient medium from 7.04 to 4.70 is observed, which is due to the assimilation of mineral and organic nitrogen by microalgae. With an increase in the duration of cultivation of microalgae, there is an increase in the number of cells in the culture fluid up to 4 × 107 cl /ml, which at the same time synthesize the extracellular enzyme β-fructosidase, hydrolyzing sucrose.Conclusions. In view of the studies obtained, it is possible to indicate the possibility of using beet molasses as a source of carbon and substances that stimulate the growth of D.salina to produce biomass, protein substances and the enzyme β-fructosidase.