Increase in carotenoid content in Vischeria punctata Vischer biomass during cultivation in a laboratory bioreactor

Microalgae Vischeria punctata Vischer, strain IPPAS H-242 (K.A. Timiryazev Institute of Physiology and Hydrology of the Russian Academy of Sciences) were cultivated in a laboratory photobioreactor; the best medium for biomass yield was Bold's medium. Addition of cyanocobalamin and thiamine to Bold's medium did not lead to an increase in biomass yield. To increase the carotenide content in the microalgae biomass, dosed exposure to various concentrations of hydrogen peroxide was used: from 0.1 to 0.3 ml/l of microalgae suspension. Pyridoxine at a concentration of 50 mg/l was added to the suspension simultaneously with hydrogen peroxide. Hydrogen peroxide and pyridoxine were added every two days during the cultivation of V. punctata, which lasted for 10 days. Hydrogen peroxide additions lead to a decrease in the duration of the exponential growth phase in the variants with the addition of 0.1 and 0.2 ml/l hydrogen peroxide for 1 day, and with the addition of 0.3 ml/l hydrogen peroxide for 2 days. Also, in response to stress, a decrease in the average cell size in the population was noted. In the variant with a hydrogen peroxide concentration of 0.3 ml/l, there is a decrease in the population capacity and the content of the sum of carotenoids in the air-dry biomass. In the variants with the addition of 0.1 and 0.2 ml/l hydrogen peroxide, an increase in the proportion of carotenoids in the pigment complex was noted compared to the control by 18.12±0.20 and 18.92±0.14%, respectively. The best variant of the experiment was the introduction of 0.2 ml of hydrogen peroxide per 1 liter of microalgae suspension, while the biomass yield did not differ significantly from the control variant, the content of the sum of carotenoids increased by 23.1% compared to the control and reached 5.97±0.11 mg/g of air-dry biomass.