Growth kinetic of Botryococcus braunii microalgae using logistic and gompertz models

Botryococcus braunii is one of microalgae species that has potential in many aspects such as energy, food, medical, etc, due to its high content hydrocarbon, especially lipid. To find optimum condition for harvesting the Botryococcus braunii, some mathematical models are needed to study its growth profile. In this research, there will be two growth models that will be used, namely the Logistic and Gompertz models. The cultivation was carried out in medium which consists of a distillate water inoculum ratio of 1:1 in simple flask photobioreactor. Walne medium which contained 50 % NaNO3, 10 % NaH2PO4, 22 % Na2EDTA, 0.18 % MnCl2, and 0.82 FeCl3 was utilized as nutrient. In this experiment, the measurement of microalgae density cells was done using haemacytometer. The obtained data were then fit Logistic and Gompertz model. The sum of the square of residual between the cells density data experiment and data from each of models was used to evaluate the most representative model. Based on the study, the Logistic model was found to produce a lower error for the growth rate curve of Botryococcus braunii. Growth parameters based on Logistic model for the cultivation of Botryococcus braunii consists of µmax= 0.7493/ (day) and Xmax 1.2647x104 (cells/ml), while in Gompertz model consists of cells productivity (rm)=2.907 x 104 (cells/ml day) and lag time (tL)=1 (day).