Sodium chloride stimulates the biomass and astaxanthin production by Haematococcus pluvialis via a two-stage cultivation strategy.

A major challenge facing by astaxanthin industrialization is the low productivity and high production costs. This study established a two-stage cultivation strategy based on the application of NaCl to improve the production of biomass and astaxanthin by Haematococcus pluvialis. During the first growth stage, 12.5 mg L NaCl led to a remarkable enhancement in biomass, which was 1.28 times compared with the control. Moreover, 2 g L NaCl stimulated the astaxanthin content from 12.18 mg g to 25.92 mg g during the second induction stage. Simultaneously, salinity stress application increased the lipids and GABA contents, as well as the levels of Ca and carotenogenic genes' expression, but suppressed the contents of carbohydrate and protein and high-light induced-ROS. This study proposed a simple and convenient strategy for efficient coproduction of biomass and astaxanthin and provides insights into the underlying mechanism of astaxanthin biosynthesis in H. pluvialis induced by salinity stress.