Preliminary investigation on the effect of Leucaena leucocephala leaves supernatant on the microalgae lipid content Botryococcus braunii

Botryococcus braunii is recognized as one of the most important microalgae species due to its high lipid content that may reach 75% of its dry weight. This amount is relatively higher than that in other microalgae species, thus potentially exploitable for biofuel production. Culture media support the growth of this microalga to sustain its culture production. Leucaena leaves supernatant (LLS) has potential as natural growth culture supplement. The present study aims to analyse the best concentration of LLS with optimum light intensity as supplement for microalgae growth by using an experimental method. This study consisted of four treatments with three replications during 14 days of experiment or one cycle of growth phase of B. braunii. The concentrations of LLS on the treatment were 2.5, 7.5 and 12.5%. The determination of light intensity for cultivation was based on the preliminary test, with 2500, 5000 and 7500 Lux. The best growth-producing light intensity was used in the main experiment. The initial density of microalgae was 100,000 cells/mL under environmental conditions of 26 °C, pH of 7.85, salinity of 30 ppt and photoperiod of 12/12 h light/dark cycle. The lipid test was carried out using Soxhlet method. The results of the study showed that LLS at 12.5% produced the highest lipid content (41.39%), while lower lipid content was found at 7.5, 2.5 and 0% of LLS (control) (37.23, 30.61 and 23.73%, respectively).