Optimization of nitrate:urea ratio and nitrogen concentration on Spirulina platensis cultivation for the production of protein and phycocyanin pigment

Abstract

The need of nitrogen (N) for the growth of Spirulina platensis and the production of protein and phycocyanin pigment is influenced by the type of source and the concentration of N contained in the growing media. Spirulina platensis can assimilate various N sources, including nitrate (NO3-) and urea. Urea is a cheap N source and easy to be obtained. Urea can also have a role as potential N source to support the growth and the metabolites production of cyanobacteria S. platensis. Partial substitution of N source (NO3-) to urea in Zarrouk medium for S. platensis cultivation has not been conducted before. This study was aiming at determining the optimum ratio of NaNO3 : CO(NH2)2 and the optimum N concentration in the Zarrouk medium for protein and phycocyanin production by S. platensis. Response Surface Method (RSM)-one factor experimental design was employed in this study for determining the optimum N concentration at specific N concentration range and optimum ratio of N source that had been previously determined. The results demonstrated that the optimum ratio of NaNO3 : CO(NH2)2 for protein and phycocyanin production was 1:1. The optimum N concentration for protein and phycocyanin pigment production in S. platensis cultivation were 5.13 mmol L-1 and 4.94 mmol L-1 with the increament in about 51.95% and 25.16%, respectively, compared to the standar Zarrouk medium.

Keywords

• blue-green algae
• zarrouk medium
• response surface methodology-one factor
• nitrogen source