Environmental
Factors Affecting the Beta-Carotene
in Spirulina platensis
Content
Aran Incharoensakdi and Saranya Phunpruch
Department of Biochemistry, Faculty of Science,
Chulalongkorn University, Bangkok 10330, Thailand
Spirulina platens is was grown in a normal Zarro uk medium. The effect of various
environmental factors on the beta-carotene content in S. platens is was investigated. The
initial pH of the medium in the range 8.0 - 11.0 did not affect beta-carotene content
although the growth of the cells was retarded at pH 10.5 and 1] .0. The temperature during
growth of the cells higher than 35°C caused a drop in beta-carotene content. Increased light
intensity up to 10,000 lux resulted in an increased beta-carotene content. When the cells
were grown under red light illumination, beta-carotene content was highest followed by
that under blue light and white light respectively. Nitrate deficiency in the growth medium
did not appear to cause an increase in beta-carotene content. The influence of the salinity of
the medium was also studied. It was found that beta-carotene content was increased with
increasing NaCI in the medium. However, a drastic rise in beta-carotene content could be
obtained by either growing the cells initially in the medium containing 20g/1 NaCI and then
transferring the cells to the new medium with 30g/1 NaCI or initially acclimating the cells in
the medium with 40g/1 NaCI and then transferring the cells to the new medium containing
the same content ofNaCI at 40g/l.
INTRODUCTION
The multicellular Spirulina platens is is a cyanobacterium which has been
studied extensively with respect to the biomass production. The valuable chemical
composition of Spirulina reflects its potential as human food, animal feed and as a
source of natural products. One of the valuable products is the pigments including
chlorophyll, phycobilins as well as carotenoids. Among the carotenoids, betacarotene represents the major component accounting for 67-79% of total
carotenoids (1). Most of the work on the content and the accumulation of betacarotene have been done on a green microalga, Dunaliella spp. This organism
contains high amount of beta-carotene under growth-limiting conditions including
high salinity, or deprivation of mineral nutrients such as nitrate or sulfate (2, 3, 4).
On the other hand the information on beta-carotene in Spirulina is scarce. This
paper will report on the effect of various environmental factors on the content of
beta-carotene in S. platens is.
MATERIALS
AND METHODS
Cultivation of S. platensis
Determination
of beta-carotene
RESULTS AND DISCUSSION
1. Effect of initial pH and temperature
on beta-carotene content
2. Effect of irradiation on beta-carotene content
3. Effect of nitrate on beta-carotene content
4. Effect of NaCI on beta-carotene content
CONCLUSION
ACKNOWLEDGMENT
REFERENCES