Biodiesel synthesis from Chlorella vulgaris under effect of nitrogen limitation, intensity and quality light:...

Cultures under nitrogen limitation for Chlorella vulgaris were kept under different light quality (white, blue, yellow and violet) at 70 and 140 µE m^-2 s^-1; to evaluate the effect on fatty acids profiles and biodiesel quality. The results showed a maximum biomass and cell density at 140 µE m^-2 s^-1 of: white light (0.69 g L^-1 and 6.5 × 10⁶ cells mL^-1, respectively) and blue light (0.65 g L^-1 and 8.0 × 10⁶ cells mL^-1, respectively); compared to violet and yellow light. The chlorophyll concentration (µg mg^-1 biomass dry weight) at 70 µE m^-2 s^-1 were in the order of light: white (25.61) > violet (17.10) > yellow (11.68) > blue (11.40) and, at 140 µE m^-2 s^-1 were: violet (23.64) > white (10.20) > yellow (9.66) > blue (7.99), suggesting the violet light stimulates the increase of chlorophyll a at higher intensity. The maximum lipid content (% w/w) were present under blue light (43.11), yellow (70.92) and violet (83.87) at 140 µE m^-2 s^-1. The different wavelengths did not have a negative effect on the quality of the biodiesel, however; violet light presented greater productivity and the indicators such as CFPP were related to the oxidative stability value and low PUFA content, leading biodiesel to good oxidative stability.