Metabolic Response of Haematococcus lacustris under the Influence of Induced-Stress: Strategies and Exogenous Toxicity of Phenol

Abstract

Under extreme environmental conditions, Haematococcus lacustris (Girod-Chantrans) Rostafinski has shown significant accumulation of astaxanthin. Nevertheless, understanding of the effects of toxic chemicals on pigment synthesis is still limited. In this study, H. lacustris was treated with phenol to investigate cellular responses, pigment synthesis and the astaxanthin production. The effects of phenol were investigated at concentrations ranging from 0 to 150 mg/L for a 14-day treatment and a 7-day pre-treatment followed by a further 7 days at the green and red growth stages. Phenol led to an increase in carotenoids, proteins and dry biomass in the green cells of treatment, while the content of carbohydrates and chlorophyll decreased in the treatment of green cells. Pretreatment increased chlorophyll a, carbohydrates and carotenoids in the green cells, with minimal effects on dry biomass, green cell proteins and red cell proteins. Phenol treatment increased the content of carotenoids, carbohydrates, dry biomass and protein in the red cells, especially at lower concentrations. Treatment with high-concentration phenol had a significant effect on xanthophylls, while pretreatment with lower concentrations of phenol showed parallel effects. Higher phenol concentrations reduced astaxanthin production in both treatment and pretreatment. In conclusion, phenol can stimulate xanthophyll production in H. lacustris algae, highlighting the complex interplay between environmental factors and pigment synthesis.