Environmental Engineering Reference
conditions and systems, as well as the robustness of the one-step system for the
outdoor production of astaxanthin-rich Haematococcus cells.
In closed photobioreactors operated under continuous mode, according to the
one-step strategy , the productivity values obtained are comparable to the max-
imum referenced values using the two-stage strategy outdoors . Obviously,
substantial effort is required for further development and scaling up prior to achiev-
ing steady operation of the one-step system at a large scale outdoors. In this context,
the generated mathematical models represent powerful tools for both design and
management of such systems. Improvements in design and operation of the photo-
bioreactors, including predictive control tools, addressed to enhance performance
and subsequent productivity, are expected to occur in the near future. The key factor
to be acted upon in order to enhance productivity of the outdoor system is the avail-
ability of light to cells in the reactor, given that nitrate availability is easier to control.
The controlled environment of the closed photobiorector certainly contributes to the
prevention of contamination of Haematococcus cultures, a most crucial issue in
outdoor handling of this valuable, but most delicate microalga.
Acknowledgements Research supported by grants from Ministerio de Ciencia e Innovación and
Junta de Andalucía, Plan Andaluz de Investigación (BIO 131 &173), Spain.
1. Del Campo J.A., García-González M., Guerrero M.G. (2007) Outdoor cultivation of microal-
gae for carotenoid production: current state and perspectives. Appl Microbiol Biotechnol 74 ,
2. Guerin M., Huntley M.E., Olaizola M. (2003) Haematococcus astaxanthin: Applications for
human health and nutrition. Trends Biotechnol 21 (5), 210-6.
3. Johnson E.A., An G.H. (1991) Astaxanthin frommicrobial sources. Crit Rev Biotechnol 11 (4),
4. Breithaupt D.E. (2007) Modern application of xanthophylls in animal feeding - a review.
Trends Food Sci Technol 18 , 501-6.
5. Todd Lorenz R., Cysewski G.R. (2000) Commercial potential for Haematococcus microalgae
as a natural source of astaxanthin. Trends Biotechnol 18 , 160-7.
6. Business Communications Company, Inc.: www.bccresearch.com
7. Higuera-Ciapara I., Félix-Valenzuela L., Goycoolea F.M. (2006) Astaxanthin: A review of its
chemistry and applications. Crit Rev Food Sci Nutr 46 (2), 185-96.
8. Hussein G., Sankawa U., Goto H., Matsumoto K., Watanabe H. (2006) Astaxanthin, a
carotenoid with potential in human health and nutrition. J Nat Prod 69 (3), 443-9.
9. Johnson E.A., Schroeder W.A. (1995) Microbial carotenoids. Adv Biochem Eng Biotechnol
10. Boussiba S. (2000) Carotenogenesis in the green alga Haematococcus pluvialis : Cellular
physiology and stress response. Physiol Plant 108 (2), 111-7.
11. Boussiba S., Vonshak A. (1991) Astaxanthin accumulation in the green alga Haematococcus
pluvialis . Plant Cell Physiol 32 (7), 1077-82.
12. Fábregas J., Domínguez A., García-Álvarez D., Lamera T., Otero A. (1998) Induction
of astaxanthin accumulation by nitrogen and magnesium deficiencies in Haematococcus
pluvialis . Biotechnol Lett 20 , 623-6.
13. Harker M., Tsavalos A.J., Young, A.J. (1996) Factors responsible for astaxanthin formation
in the chlorophyte Haematococcus pluvialis . Bioresour Technol 55 (3), 207-14.