Enhancement of carotenoid biosynthesis in the green microalga Dunaliella salina with light-emitting diodes and adaptive laboratory evolution

Weiqi Fu,Giuseppe Paglia,Bernhard Ø Palsson,Sigurður Brynjólfsson,Ólafur S Andrésson,Ólafur Guðmundsson,Gísli Herjólfsson

doi:10.1007/s00253-012-4502-5

Abstract

There is a particularly high interest to derive carotenoids such as β-carotene and lutein from higher plants and algae for the global market. It is well known that β-carotene can be overproduced in the green microalga Dunaliella salina in response to stressful light conditions. However, little is known about the effects of light quality on carotenoid metabolism, e.g., narrow spectrum red light. In this study, we present UPLC-UV-MS data from D. salina consistent with the pathway proposed for carotenoid metabolism in the green microalga Chlamydomonas reinhardtii. We have studied the effect of red light-emitting diode (LED) lighting on growth rate and biomass yield and identified the optimal photon flux for D. salina growth. We found that the major carotenoids changed in parallel to the chlorophyll b content and that red light photon stress alone at high level was not capable of upregulating carotenoid accumulation presumably due to serious photodamage. We have found that combining red LED (75 %) with blue LED (25 %) allowed growth at a higher total photon flux. Additional blue light instead of red light led to increased β-carotene and lutein accumulation, and the application of long-term iterative stress (adaptive laboratory evolution) yielded strains of D. salina with increased accumulation of carotenoids under combined blue and red light.Electronic supplementary materialThe online version of this article (doi:10.1007/s00253-012-4502-5) contains supplementary material, which is available to authorized users.

Highlights

Microalgae have great potential in many aspects of the conversion of conventional petrol-based manufacturing to biobased manufacturing: in production of biofuels as well as biofactories producing valuable pharmaceuticals, food additives, and cosmetics (Cordero et al 2011; Lamers et al 2008; Takaichi 2011; Vilchez et al 2011; Wijffels and Barbosa 2010)
This study has provided data relating to such an issue, the photosynthesis-based production of valuable compounds such as β-carotene and lutein using microalgae
The use of well-designed light-emitting diode (LED) lighting for D. salina illustrates the potential for enhancing sustainable production of carotenoid products such as β-carotene and lutein efficiently by microalgal biotechnology (Lamers et al 2008; Ribeiro et al 2011)

Summary

Introduction

Microalgae have great potential in many aspects of the conversion of conventional petrol-based manufacturing to biobased manufacturing: in production of biofuels as well as biofactories producing valuable pharmaceuticals, food additives, and cosmetics (Cordero et al 2011; Lamers et al 2008; Takaichi 2011; Vilchez et al 2011; Wijffels and Barbosa 2010). Carotenoids are extremely important for human and animal nutrition, and they are distributed broadly in both phototrophic and non-phototrophic organisms (Takaichi 2011). Humans and animals cannot synthesize necessary carotenoids and must obtain them from their diets (Takaichi 2011). Carotenoids can be divided into two groups based on their chemical structure: the carotenes such as βcarotene and the xanthophylls such as lutein. Among important carotenoids for humans, β-carotene is a major source of vitamin A which is necessary for functions of the retina and has an effect on many tissue types (Amengual et al 2011; von Lintig et al 2005) through its action as a regulator of gene expression.

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