Effects of red and blue light emitting diodes on biomass and astaxanthin of Haematococcus pluvialis in pilot scale angled twin-layer porous substrate photobioreactors

Astaxanthin has been shown to be one of the most powerful antioxidants out of many other carotenoids. Astaxanthin can be found in the shells of crustaceans, seafood, the yeast Phaffia rhodozyma, and in some bacteria at low concentrations. However, the green alga Haematococcus pluvialis is able to synthesize and accumulate astaxanthin in high and is thus used to produce astaxanthin on an industrial scale. The production of natural astaxanthin is usually accomplished by suspended cultivation of the microalgae Haematococcus pluvialis (open or closed systems). In this study, for the purpose of cost reduction, H. pluvialis is grown in pilot scale angled twin-layer porous substrate photobioreactors with light energy from red/blue LEDs that can produce red light, blue light, or a combination of blue-red light. The total dry biomass of the microalgae reached a maximum of 40.74 g.m-2 under blue-red LEDs. The early initiation of blue-red LED illumination (on day 2) after algae immobilization in the biofilm resulted in the highest accumulation of astaxanthin in the dry biomass, which reached a maximum of 1.3% (w/w) after 10 d of culture.