Development of fertilizer-based medium for the growth rate improvement of Chlorella sp. in the laboratory scale

Abstract

Microalgae are unicellular photosynthetic microorganisms, ubiquitous in nature which can be found in freshwater, seawater, hypersaline lakes, even in deserts and arctic ecosystems. Chlorella sp. is a eukaryotic, unicellular, photosynthetic organism with a spherical shape of about 1 to 20 μm in diameter. In this study, the combination of commonly used Walne medium and commercial fertilizers (ZA, TSP and Urea) were proposed as a low-cost approach for the cultivation of Chlorella sp. in the laboratory basis. The modified commercial fertilizer medium formulation consisted of the combination of at least 5% of Walne with different proportion of ZA, TSP and Urea. The result indicated that the combination of 5% (v/v) Walne and 95% (v/v) urea was able to retain the algal growth as compared to the combination of Urea, TSP and ZA. The obtained specific growth for 5% (v/v) Walne and 95% (v/v) urea modified medium was 0.246 d-1 and biomass productivity resulted 28 mg/L/d, which was comparable with commonly used Walne medium. Therefore, urea was primarily considered as the most suitable nitrogen source to support the growth of Chlorella sp. in the laboratory basis. Furthermore, modified commercial fertilizer medium developed in this study could potentially substitute the enriched medium used in the laboratory for the outdoor large-scale cultivation of microalgae.