Electronic Theses and Dissertation

Mikroalga mampu mensintesis berbagai senyawa biologis seperti karotenoid, lipid, dan protein, yang dapat digunakan dalam suplemen, industri kosmetik, pangan, dan bioenergi. Penelitian ini mempelajari pengaruh variasi salinitas dan suhu terhadap produksi karotenoid dan aktivitas antioksidan dari mikroalga Nannochloropsis sp. Penelitian dilakukan pada variasi salinitas 20, 30, 35, dan 40 ppt serta variasi suhu 18, 25, 30, dan 35 ℃. Pertumbuhan mikroalga ditentukan berdasarkan Optical density (OD) pada panjang gelombang 680 nm dan berat sel kering. Ekstrak etanol mikroalga Nannochloropsis sp. digunakan untuk analisis kandungan karotenoid berdasarkan metode Lichtenthaler dan Buschmann menggunakan spektrofotometer UV-Vis. Aktivitas antioksidan dari ekstrak diuji menggunakan metode DPPH (2,2-diphenyl-1- picrylhydrazyl). Pada percobaan variasi salinitas, kandungan karotenoid tertinggi dan terendah masing-masing diperoleh pada salinitas 35 ppt (37,2 μg/mL) dan salinitas 20 ppt sebanyak (20,7 μg/mL). Pada percobaan variasi suhu, kandungan karotenoid teringgi tertinggi dan terendah teramati masing-masing pada suhu pertumbuhan 25°C (37,2 μg/mL) dan suhu 30°C (3,6 μg/mL). Aktivitas antioksidan terbaik ekstrak etanol pada perlakuan salinitas termatio pada salinitas 40% dengan nilai IC50 sebesar 142 ppm. Sementara itu pada perlakuan suhu, aktivitas antioksidan paling efektif termati
pada suhu 30℃ dengan nilai IC50 sebesar 262 ppm. Hasil penelitian ini membuktikan bahwa perbedaan salinitas dan suhu berpengaruh terhadap produksi karotenoid dan aktvitas antioksidan Nannochloropsis sp.

Kata kunci: Mikroalga, Nannochloropsis sp., karotenoid, salinitas, suhu, dan
antioksidan

Microalgae can synthesise various biological compounds, such as carotenoids, lipids, and proteins, which can be utilised for supplements, cosmetic formulations, food, and bioenergy feedstocks. This research examined the effects of salinity and temperature variations on the production of carotenoids with antioxidant activity by the microalga Nannochloropsis sp. The study was conducted using salinity levels of 20, 30, 35, and 40 ppt, and temperature levels of 18, 25, 30, and 35℃. Microalgae growth was determined by optical density (OD) at 680 nm and dry cell weight. Ethanol extracts of Nannochloropsis sp. cells were analysed for carotenoid content based on the Lichtenthaler and Buschmann method using a UV-Vis spectrophotometer. The antioxidant activity of the extract was tested using the DPPH (2,2-diphenyl-1- picrylhydrazyl) method. In the salinity variation experiment, the highest and lowest carotenoid contents were obtained at salinities of 35 ppt (37.2 μg/mL) and 20 ppt (20.7 μg/mL), respectively. In the temperature variation experiment, the highest and lowest carotenoid contents were observed at temperatures of 25℃ (37.2 μg/mL) and 30℃ (3.6 μg/mL), respectively. The ethanol extract showed the highest antioxidant activity at 40% salinity, with an IC50 of 142 ppm. Meanwhile, in the temperature treatment, the most effective antioxidant activity was observed at 30℃ with an IC50 value of 262 ppm. The results demonstrated that differences in salinity and temperature affect the production of carotenoids and their antioxidant activity from Nannochloropsis sp. Keywords: Microalgae, Nannochloropsis sp., carotenoids, salinity, temperature, antisoxidant