Understanding Urea Assimilation and its Effect on Lipid Production and Fatty Acid Composition of Scenedesmus Sp

nitrogen concentration, temperature and light intensity. Nitrogen is one of the essential nutrients critical for the cultivation of algae due to its role in growth and regulation of metabolism [1]. It is well documented that there are three different sources of nitrogen such as nitrate, ammonia and urea, which are absorbed by microalgae [2,3]. Urea is known to contain approximately 46.7% nitrogen content, that is, 0.467 Kg of urea–N and hence it is considered as a low-cost and efficient form of nitrogen when compared to other sources [4,5]. Under typical water conditions, urea gives rise to nutrients such as N, P and C (100%) and thus is supplied as a chemical fertilizer to the culture medium for algal uptake [4]. Conversely, nitrate (sodium or potassium salt) provides only 16% of nitrogen, 100% of which is readily available for the culture due to its efficient water-soluble property [5]. The above-mentioned increase in the availability of nitrogen source through urea as compared to other sources of nitrogen is observed due to the presence of two nitrogen atoms per mole of urea. Urea also proves to be an efficient alternative source to other nitrate forms as its cost of production and price per kg of N available is much lower (price per kg of sodium nitrate is 3.1 times that of urea; Table 1).