OPTIMASI PRODUKSI LIPID CHLORELLA VULGARIS DENGAN DEFISIENSI NITROGEN SERTA STRATEGI KULTIVASI DUA TAHAP MENGGUNAKAN MEDIUM PUPUK KOMERSIL

• Main Author: Luluh Lengingtyas M., Gama
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67093
• Institution: Institut Teknologi Bandung

The two-stage cultivation strategy is one of the alternatives that has been widely developed to increase lipid productivity and change the lipid profile that determines the quality of biodiesel. This strategy is generally conducted by applying stress in the second stage of cultivation to induce lipid accumulation by microalgae cells. This study aims to: (i) Determine the optimum harvest time in the first stage of cultivation based on the growth phase of the amount of lipid and maximum lipid productivity of Chlorella vulgaris in the second stage of cultivation; (ii) Determine the optimum duration of stress on total lipid and maximum lipid productivity of Chlorella vulgaris in the second stage of cultivation; and (iii) Determine the suitability of the fatty acid profile of Chlorella vulgaris from the results of twostage cultivation with the optimum harvest time and duration of stress as biodiesel feedstock. C. vulgaris was grown on Nutri-comp D fertilizer medium (0,72 g/L) in the first stage of cultivation, then transferred to SP-36 fertilizer medium (35 mg/L) under nitrogen deficiency conditions in the second stage of cultivation. Comparison of lipid accumulation was carried out to determine the optimum harvest time of the first stage based on the growth phase and duration of stress during the second stage of cultivation. The lipids were extracted using a mixed solvent of chloroform methanol. The fatty acid profiles of the two cultivation phases were analyzed using GC-FID (FastFAME DB Column). The condition of nitrogen stress in the second stage significantly affected lipid accumulation (p<0.05). The final lipid content of microalgae in the second stage nitrogen-limited condition (8,2-28,5% w/w) was higher than the final lipid content in the first stage nitrogen-rich condition (6,4- 8,1% w/w). The results showed that the duration of nutritional stress which resulted in optimum lipid content was 8 days of cultivation and the time of onset of nutritional deficiency which resulted in optimum lipid content of 28,5% (w/w) was in the final stationary growth phase. The fatty acid profile in the second stage showed the composition of saturated fatty acids, polyunsaturated fatty acids, and monounsaturated fatty acids in C. vulgaris were 60,23%, 22,80% and 16,98% (w/w) respectively. C. vulgaris which was cultivated in the second stage under nitrogen stress had a high total lipid and a fatty acid profile that was close to ideal as biodiesel feedstock.