Photoautotrophic Production of Astaxanthin by the Microalga Haematococcus pluvialis - Sustainable Biotechnology: Sources of Renewable Energy - page 253

Ta b l e 1 Analysis of variance for astaxanthin content and productivity in continuous cultures of
H. pluvialis as influenced by specific nitrate input and average irradiance (

α =

0.05; n =

43)

Astaxanthin (mg g -1 ) Astaxanthin productivity (mg l -1 d -1 )

Va r i a b l e F p-value F p-value

SNI 49.74 0.0000 28.61 0.0000

Iav 5.29 0.0040 5.26 0.0041

of the system (Table 1). No doubt, these intensive variables control the behavior
of the system. On these grounds, models have been developed that relate growth
rate and astaxanthin accumulation with both average irradiance and specific nitrate
input; these models accurately fit experimental data [48]. Efficient production of
the carotenoid can be achieved through appropriate adjustment of the determining
parameters. Thus, the developed model accurately reflects the behavior of the sys-
tem, and allows estimation of productivity even for high average irradiance values
(Fig. 3).
Productivity of astaxanthin by H. pluvialis in the one-step system compares
favorably with any value obtained so far for the two-stage system operating under
continuous illumination indoors. Notwithstanding, substantial effort is required for
further development and scaling up prior to achieving 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
[44, 48].
Although developments are obviously required, the one-step approach for astax-
anthin production represents a serious alternative to the two-stage strategy. Besides

Fig. 3 Surface response curve of astaxanthin productivity by H. pluvialis in the one-step system
as influenced by specific nitrate input and average irradiance