Photoautotrophic Production of Astaxanthin by the Microalga Haematococcus pluvialis - Sustainable Biotechnology: Sources of Renewable Energy - page 247

Photoautotrophic Production of Astaxanthin
by the Microalga Haematococcus pluvialis

Esperanza Del Río, F. Gabriel Acién, and Miguel G. Guerrero

Abstract The global market for astaxanthin -the red carotenoid responsible for the
color of salmon flesh, crustacean shells or flamingo feathers- rises markedly, with
a preferential demand for the natural pigment from the microalga Haematococcus
pluvialis . Current methodology for the production of astaxantin-rich cells follows a
two-stage approach, first producing biomass under optimal growth conditions and
then exposing the alga to adverse environmental conditions that promote encyst-
ment and accumulation of the carotenoid. An improved methodology involving a
one-step-only continuous production strategy has been developed recently. Specific
nitrate input and average irradiance are the most relevant parameters in determining
the behavior of this continuous system that generates reddish vegetative cells, with
astaxanthin representing more than 1% of the dry biomass. Feasibility of the method
has been carefully analyzed indoors and verified outdoors in a tubular photobiore-
actor. Its singular capacity, besides a high quality of the reddish biomass product,
made the system a real alternative to the two-stage option generating hard-walled
red cysts.

Keywords Astaxanthin · Carotenoid · Continuous culture · Haematococcus ·

Irradiance · Nitrate input · Photobioreactor

1 Introduction

Microalgae combine properties typical of higher plants (efficient oxygenic pho-
tosynthesis and simplicity of nutritional requirements) with biotechnological
attributes proper to microbial cells (fast growth in liquid culture and the ability
to accumulate or secrete some metabolites). This particular combination supports