Effects of Different Levels of Urea as Nitrogen Source on Chemical Composi- tion of Marine Microalgae Nannochloropsis oculata

Abstract

Microalgae breeding media must be cost-effective, enable high growth, meet exact re- quirements and be readily available. The effect of different levels of urea [25, 50, 75, and 100%] in the growth medium on the biochemical constituents (protein, carbohydrates, lipids, fatty acids, and amino acids) of the Nannochloropsis oculata, was assessed compared to the F/2 Guillard standard medium. The obtained results revealed that the chemical constituents of N. oculata were influenced by the different levels of urea. The highest total protein was obtained by A4 medium (100% urea) (26.44%) and A3 medium (75% urea) (25.84%). The maximum percentage of essential amino acids (EAA) (51.54%) was obtained by using the A4 medium (100% urea) as compared to the control (100% F/2). The highest total lipid content was achieved by using the A1 medium (25% urea) pro- ducing (17.33 %) and A4 medium (100% urea) (16.98%). Accordingly, the highest total saturated fatty acids percentage (TSFA) of N. oculata was recorded by the A3 medium. In conclusion, the addition of urea is an excellent policy to increase chemical composition and lipid accumulation. The present study recommended taming results for aquaculture feeding through using the proposed A1 medium as a lipid promoter or A4 medium as a protein promoter.