We studied the growth of copper-sensitive (CuS D. v.) and copper-resistant (CuR D. v. 75) strains of the green microalga Dunaliella viridis Teodoresco at 35 oС to determine the relationship between the induced resistance to copper ions and resistance to high temperature of the environment. The effect of stepwise temperature increasing from 24 → 29 → 35 °C with an interval of 7 days on the growth rate and biomass composition (content of DNA, RNA, protein, triacylglycerides (TG), carotenoids and chlorophyll) of CuS D. v. and CuR D. v. cultures was examined. It was revealed that a temperature increase of up to 35° in the culture of CuS D. v. at the initial stage of growth slows its growth; the culture CuR D. v. 75 dies under the same conditions. With a stepwise increase in the temperature of cultivation (24 → 29 → 35 °C), the culture CuR D. v. 75 survives, its growth rate is slightly higher than in CuS D. v. proving the thermal stability of its cells. In addition, biomass of CuR D. v. 75 contains more protein, DNA, TG, and especially β-carotene, compared to CuS D. v. At a temperature of 35 °C, the content of protein, DNA, TG, and β-carotene in cells of CuS D. v. also increased. It has been found that there is a complex relationship between resistance to copper ions and resistance to high temperature, which is determined by the temporal nature of the temperature change.
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