3.3 FAME analysis
FAME profile showed ~ 2-fold increase in glycerol supplemented cultures (M1, M2, M3, M4), where ~97 mg L-1 of lipid was obtained in the M4 condition, which is ~ 40 % higher as compared to P1 and 8 % as compared to M3 cultures (Table 2) . Glycerol in the form of reduced carbon source affects lipid metabolism by mimicking most of the effects of nitrogen limitation[52, 55], hence the storage molecules i.e. triacylglycerol (TAGs) are accumulated in M3 culture. Moreover, significant variations were observed in FAME profile (% total fatty acid) in different culture conditions (Table 2) . Saturated and monounsaturated fatty acid percentage were higher in P1, P3, M1, M2 and M3 supplemented cultures, whereas P2 and M4 cultures showed a higher polyunsaturated fatty acid percentage. EPA being the major long chain fatty acid in P. tricornutum was highest among all other fatty acid species in all the conditions but ~2-fold increase of EPA % of total fatty acid (TFA) was observed in M4, accounting for 28% of TFA (Table 2). These results imply that feeding with cost effective nitrogen source can be used as an effective strategy to enhance the omega-3 production in P. tricornutum.