Influence of ethanol on the productivity of Haematococcus pluvialis, content of photosynthetic pigments, reactive oxygen species and astaxantin

Abstract

The effect of ethanol (0.1, 0.3, and 1.6 %) on the content of photosynthetic pigments, astaxanthin, and reactive oxygen species (ROS) in Haematococcus pluvialis (H. pluvialis, strain IBCE H-17), as well as on algae productivity, was studied in terms of dry biomass. Ethanol was found to stimulate in the studied concentrations the accumulation of dry biomass for 3, 7, and 12 days of cultivation on average 2 times. At all used ethanol concentrations, the number of cells increased. So, when using 0.3 % ethanol, the number of cells increased by 2.1; 2.5 and 3.3 times compared with the control culture on days 3, 7 and 15 of haematococcus cell growth. At the same time, a tendency toward a decrease in their size was noted. Ethanol also stimulated the accumulation of photosynthetic pigments. So, after 3 days of incubation in a solution containing 0.1 and 0.3 % ethanol, the content of chlorophyll (Chl) a was 142 and 130 % of that in the control, respectively, Chl b – 126 and 115 %, lutein – 151 and 132 %. The maximum effect was noted for β-carotene – 177 and 157 % compared with the control. The stress conditions created by ethanol led to the generation of ROS, in particular, after 7 days of incubation using 0.1; 0.3 and 1.6 % ethanol, the amount of ROS was 114, 141 and 179 % of that in the control, and after 12 days of incubation, 130, 165 and 183 %, respectively. A significant positive effect of ethanol on the content of astaxanthin was noted. So, after 7 days of incubation, the content of astaxanthin in options of 0.1; 0.3 and 1.6 % increased by 3.6; 4.9 and 4.6 times, respectively, and after 12 days – 8.6; 6.6 and 7.7 times compared with the control. The results indicate the enormous potential of using ethanol as an effective inducer of astaxanthin accumulation in haematococcus cells, as well as an active stimulator of algal productivity.