Effect of nitrogen on lipid production of Chlorococcum novae-angliae

Selecting the appropriate algal species is essential to maximize lipid extraction from microalgae. Chlorococcum sp. is a unicellular organism found in both aquatic and terrestrial habitats. Although the influence of nitrogen on lipid metabolism is well established across various microalgae, its particular effects on Chlorococcum sp. provide novel insights into this relatively underexplored species. Examining how nitrogen affects lipid accumulation in Chlorococcum sp. could reveal new strategies to enhance its application in biodiesel productions. This study aimed to evaluate the lipid content of Chlorococcum novae-angliae and compare the lipid and fatty acid yields between cultures grown in N-supplied and N-starvation culture media. The results show that Chlorococcum sp. cultivated in N-supplied culture medium reached the highest cell count of 2.16 ± 8.18 × 10^− 8 cells/mL, with a specific growth rate (µ) of 0.55 d^− 1, whereas a cell count of 1.60 ± 6.63 × 10^− 8 cells/mL was found for the N-starvation culture medium. On the other hand, the highest lipid yield, recorded as 0.098 ± 0.012 g lipid/g wet biomass, mainly consisting of tridecanoic and palmitic acids (77%), was obtained from the N-starvation culture medium. Tridecanoic acid (C13:0) was detected for the first time in C. novae angliae. For the N-supplied culture medium, the lipid yield was 0.082 ± 0.010 g lipid/g wet biomass. Therefore, in cases where maximizing lipid yield is crucial, such as for biofuel production, nitrogen starvation might be a more effective approach, even though it may result in lower overall biomass productivity. However, for applications that prioritize higher biomass, such as animal feed, ensuring sufficient nitrogen levels could be more beneficial.