Electronic Theses and Dissertation

Nannochloropsis sp. merupakan salah satu mikroalga yang berpotensi dikembangkan sebagai sumber senyawa bioaktif dan antioksidan alami. penelitian ini bertujuan untuk mengetahui pengaruh variasi panjang gelombang dan durasi pencahayaan led terhadap produksi karotenoid dan aktivitas antioksidan mikroalga nannochloropsis sp. kultivasi mikroalga dilakukan pada media walne dengan dua tahap (produksi biomassa dan induksi karotenoid). induksi karotenoid dilakukan meliputi variasi panjang gelombang cahaya led (putih, merah, biru, dan hijau) serta durasi pencahayaan. mikroalga yang tumbuh dianalisis berdasarkan nilai od₆₈₀ dan berat kering sel, sedangkan kandungan karotenoid ditentukan secara spektrofotometri uv vis dan aktivitas antioksidan dianalisis menggunakan metode dpph. hasil penelitian menunjukkan bahwa pertumbuhan biomassa mikroalga tertinggi diperoleh pada perlakuan cahaya led putih dengan durasi pencahayaan 24 jam terang. sementara itu, produksi karotenoid tertinggi dihasilkan pada perlakuan cahaya led merah dengan durasi 24 jam terang sebesar 32,7 µg/ml. aktivitas antioksidan ekstrak etanol nannochloropsis sp. ditemukan paling efektif pada perlakuan cahaya led merah dengan durasi 24 jam terang dengan nilai ic₅₀ sebesar 295 ppm. hasil ini membuktikan bahwa variasi panjang gelombang led dan durasi pencahayaan led berpengaruh terhadap produksi karotenoid dan aktivitas antioksidan mikroalga nannochloropsis sp. kata kunci: mikroalga, nannochloropsis sp., karotenoid, light emitting diode (led), dan antioksidan

Nannochloropsis sp. is a microalgae that has the potential to be developed as a source of bioactive compounds and natural antioxidants. This study aimed to determine the effects of variations in Light Emitting Diode (LED) wavelength and duration on carotenoid production and antioxidant activity in Nannochloropsis sp. The cultivation was carried out using Walne media with a two-stage method (biomass production and carotenoid induction). Carotenoid induction was carried out by varying the LED wavelengths (white, red, blue, and green) and the lighting duration. The growing microalgae were analysed for OD₆₈₀ and cell dry weight, while carotenoid content was determined by UV-Vis spectrophotometry, and antioxidant activity was analysed using the DPPH method. The results showed that the highest microalgae growth was obtained with the white LED treatment and a 24-hour bright-light duration. Meanwhile, the highest carotenoid production was observed under red LED light, with a 24-hour bright-light duration of 32.7 µg/mL. The antioxidant activity of the ethanol extract of Nannochloropsis sp. was most effective under a 24-hour red LED treatment, with an IC₅₀ of 295 ppm. These results prove that variations in LED wavelength and LED lighting duration affect carotenoid production and antioxidant activity of Nannochloropsis sp. microalgae. Keywords: Microalgae, Nannochloropsis sp., carotenoids, light emitting diodes (LEDs), and antioxidants.