Photoautotrophic Production of Astaxanthin by the Microalga Haematococcus pluvialis - Sustainable Biotechnology: Sources of Renewable Energy - page 248

the use of these microorganisms for applied processes, and represents the basis of
Microalgal Biotechnology. Microalgae are a major natural source for a vast array of
valuable compounds, including a diversity of pigments, for which these photosyn-
thetic microorganisms represent an almost exclusive renewable resource. Yellow,
orange and red carotenoids have an industrial use in food products and cosmetics,
as vitamin supplements and health food products, and as feed additives for poultry,
livestock, fish and crustaceans. The growing worldwide market value of carotenoids
is projected to reach over US $ 1,000 million by the end of the decade [1].
Astaxanthin is one of the most appreciated carotenoid pigments with applications
in nutraceuticals, cosmetics, and food and feed industries. The major market for
astaxanthin is as a pigmentation source in aquaculture, primarily salmon and trout
[2-4]. The annual worldwide astaxanthin market is estimated to be about US$ 250
million [5, 6] at a price of about US$ 2,500 per kg. Most of this market is based on
the synthetic carotenoid, the cost of this supplement representing around 10-15% of
the salmon feed price [3]. The nutraceutical market for astaxanthin is increasing very
fast on the basis of a growing variety of applications related to human health and
nutrition [2, 7, 8]. The increase of consumers' demand for natural products provides
an opportunity for natural astaxanthin although, despite technological progress in
the current production process, natural astaxanthin cannot yet compete in price with
the synthetic one [2].
Common sources of natural astaxanthin are the green algae Haematococcus plu-
vialis and the yeast Phaffia rhodozyma , as well as crustacean byproducts [7], but
only that derived from Haematococcus or Phaffia might compete economically with
synthetic astaxanthin. Currently, the yeast is manufactured by natural fermentation
and marketed as a powder containing about 0.8% astaxanthin, utilized as an ingre-
dient for salmonids feed [7]. However, the low yield of the production process has
limited the further development of this pigment source [9].
The unicellular microalga Haematococcus pluvialis (Chlorophyceae) represents
the richest source of natural astaxanthin, with its cysts or aplanospores accumulating
over 3% astaxanthin, mainly in esterified form [10]. H. pluvialis is a natural inhabi-
tant of temporary, small freshwater pools. It has a complex and not well defined life
cycle, although a general consensus exists with regard to its main morphotypes. In
its vegetative (growing and dividing) stage, both motile (flagellated) and non motile
(palmelloid) cells (Fig. 1a, b) can be found. Green vegetative cells predominate

a b c

Fig. 1 Haematococcus pluvialis morphotypes: Flagellated ( a ); Palmelloid ( b ); Aplanospore ( c )