Impact of Different Nutrient Enrichment Concentrations on the Growth of Microalga Nannochloropsis sp. (Monodopsidaceae) Culture

Microalgae consist of unicellular algal species that can produce and accumulate a wide variety of biomolecules. In order to maintain a high cell density in a continuous phototrophic culture of algae, the nutrient can serve as the most important factor in enhancing cell density. In this study, the effect of different concentrations of nutrients on the cell density of microalga Nannochloropsis sp. cultured in the mega plastic box (with 50 L capacity) was investigated. Four groups of treatment with four replicates were tested: group A (including 5 g of ferric chloride, ammonium phosphate, and Urea), group B (including 10 g of ferric chloride, ammonium phosphate, and urea), group C (including 15 g of ferric chloride, ammonium phosphate, and urea), and group D (including 15 g of ferric chloride, ammonium phosphate, and urea with 40 g of cow manure). Results revealed that group C and group D achieved maximum density on day three as 86.39×106 cell m and 85.59×106 cell m, respectively, which were significantly (p≤0.05) higher than the cell density of groups A (58.01×106 cell m) and group B (70.67×106 cell m). Additionally, the increasing specific growth rate (SGR) of Nannochloropsis sp. cultured was obtained in group D at 0.308 after the culture period. From the result of the study, it is concluded that the concentrations of 15 g ferric chloride, ammonium phosphate, and urea (group C) and 15 g ferric chloride, ammonium phosphate, and urea combined with 40 g cow manure (group D) are capable of increasing cell density growth of microalga Nannochloropsis sp. cultured in a mega plastic box.