Effect of auxin plant hormones on growth and biochemical composition of microalgae Phaeodactylum tricornutum Bohlin, 1897

Abstract

Regulation of the growth rate of Phaeodactylum tricornutum opens up prospects for the organization of efficient industrial production of live feed biomass. We studied the effect of two plant hormones, indole-3-butyric acid (3-IBA) and indole-3-acetic acid (3-IAA), on the growth and biochemical composition of Ph. tricornutum in an enrichment culture. The effective 3-IBA concentration of 0.2 ∙ 10–5 M increased the density of the culture by 373% on day 14of cultivation compared to the control. High concentrations of 3-IAA either inhibited the development of the culture or did not have a significant effect on its growth. A stimulating effect of exposure to 3-IAA at 0.1 ∙ 10–5 M on the growth was recorded on day 12 of cultivation and amounted to 328.2% compared to the control. A stimulating effect of 3-IBA exposure on protein accumulation was recorded on day 4 of cultivation and amounted to 27.9% compared to the control. A stimulating effect of 3-IAA on protein synthesis was recorded on day 12 of cultivation of Ph. tricornutum. The protein concentration during this period was 1.2-fold higher than in the control. Indole-3-butyric acid did not have any effect on lipid accumulation, compared to the control, throughout the cultivation time. On day 14 of cultivation under the exposure to 3-IAA, the concentration of lipids was 1.5-fold higher than in the control and in the group exposed to 3-IBA. Indole-3-butyric acid did not show any effect on the accumulation of carbohydrates in the Ph. tricornutum culture throughout the cultivation period. On day 4 of cultivation, the carbohydrate concentration in the culture exposed to 3-IAA increased by 240% compared to the control. At the end of the experiment (14 days), no significant differences between the experi-mental cultures in the carbohydrate concentration were observed. For 8 days of Ph. tricornutum cultivation, the chlorophyll concentration increased by 927.4 and 1 178.6% as a result of exposure to 3-IBA and 3-IAA, respec-tively.