A novel strategy for the hyper-production of astaxanthin from the newly isolated microalga Haematococcus pluvialis JNU35

Abstract

The two-stage cultivation system is widely employed for natural astaxanthin production using Haematococcus pluvialis, but the high biomass concentration of green vegetative cells (GVCs) is often difficult to achieve and little has been known about the combined photoinduction effect of light path (LP, inner diameter of 3 cm or 6 cm) and illumination mode (IM, unilateral or bilateral high light illumination). On the basis of isolating an excellent astaxanthin-producing algal strain (named H. pluvialis JNU35) and the optimized nutrient conditions, this study innovatively investigated the combined effect of LP and IM on biomass and astaxanthin hyper-production by this isolate. As a result, H. pluvialis JNU35 exhibited an ultrahigh biomass concentration of 20.1 ± 0.2 g/L and astaxanthin productivity of 18.1 mg/L/d under an optimum photoinduction combination (6 cm LP in the green stage, 3 cm LP in the red stage with bilateral high light illumination) in column photobioreactors. Moreover, an appropriate phase of GVCs being transferred into the red inductive stage was also determined to further increase the biomass concentration to 27.3 ± 0.6 g/L. By combining above optimal culture conditions, a novel culture strategy for enhancing astaxanthin production was proposed and validated in a flat-plate photobioreactor, which achieved a significant amount of astaxatnthin (5.6%, wt%) and a higher biomass concentration (3.0 g/L). This novel strategy will provide a technical solution for high-titer astaxanthin production from H. pluvialis for industrial scale.