64 VOLUME 4 NOMOR 2 DESEMBER 2017 ISSN 2548 – 611X JURNAL BIOTEKNOLOGI & BIOSAINS INDONESIA Homepage Jurnal: http://ejurnal.bppt.go.id/index.php/JBBI EFFECT OF NITROGEN SUPPLY IN CULTURE MEDIA AND LIGHT INTENSITY ON PHOTOSYNTHESIS OF Chlamydomonas reinhardtii Pengaruh Suplai Nitrogen pada Media Kultur dan Intensitas Cahaya Terhadap Proses Fotosintesis Chlamydomonas reinhardtii Bedah Rupaedah 1 , Yuichiro Takahashi 2 1 Laboratory for Biotechnology, BPPT, Building 630 PUSPIPTEK Area, Tangerang Selatan, Banten 15314 2 Photosynthesis Research Center, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan *Email: bedah.rupaedah@bppt.go.id Abstract Organisms use nitrogen to produce, among others, amino acids, proteins, and nucleic acids. In this study, the effects of various concentrations of ammonium in culture media on the photosynthetic performance of Chlamydomonas reinhardtii were done under two light conditions: low and high intensity. The microbes were grown at low (75% NH 4 Cl dosage), normal (100% NH 4 Cl dosage, which was 2 M NH 4 Cl), and high (125% NH 4 Cl dosage) nitrogen content. Cells density and chlorophyll content were quantitatively determined. Immunoblotting technique was used to separate proteins based on molecular mass. In both low and high light intensity, cells grown in 75% NH 4 Cl dosage culture medium showed lower cell density and chlorophyll concentration than those grown in 100% and 125% NH 4 Cl dosage media. The later two media produced almost the same amount of cell density and chlorophyll concentration. In conclusion, 75% NH 4 Cl dosage was insufficient for C. reinhardtii cells to grow well. The results also showed that accumulation of photosystem I (PsaA and PsaD/F) and light harvesting complex II (LHCII) were higher in low light than in high light intensity. Keywords: Chlamydomonas reinhardtii, chlorophyll, light intensity, nitrogen, photosynthesis Abstrak Organisme menggunakan nitrogen diantaranya untuk memproduksi asam amino, protein, dan asam nukleat. Dalam percobaan ini pengaruh berbagai konsentrasi amonium dalam media pada fotosintesis Chlamydomonas reinhardtii dilakukan di bawah dua kondisi cahaya: intensitas rendah dan tinggi. C. reinhardtii ditumbuhkan dalam medium dengan dosis nitrogen (N) rendah (75% dosis NH 4 Cl), normal (100% dosis NH 4 Cl, yakni NH 4 Cl 2 M), dan tinggi (125% dosis NH 4 Cl). Parameter yang diukur adalah kepadatan sel dan konsentrasi klorofil. Analisis protein dilakukan dengan imunobloting untuk memisahkan protein berdasarkan massa molekul. Pada intensitas cahaya rendah dan tinggi, sel-sel pada medium dengan 75% NH 4 Cl menunjukkan kepadatan sel dan konsentrasi klorofil lebih rendah dibandingkan dengan 100% NH 4 Cl dan 125% NH 4 Cl, di mana kedua media ini menghasilkan kepadatan sel maupun konsentrasi klorofil yang hampir sama. Dengan demikian dapat disimpulkan bahwa 75% NH 4 Cl tidak cukup bagi C. reinhardtii untuk tumbuh dengan baik. Selain itu, akumulasi fotosistem I (PsaA dan PsaD/F) dan kompleks pemanenan cahaya II (LHCII) lebih tinggi pada sistem fotosintesis dengan intensitas cahaya rendah dibandingkan cahaya tinggi. Kata kunci: Chlamydomonas reinhardtii, fotosintesis, intensitas cahaya, klorofil, nitrogen Received: 01 July 2016 Accepted: 24 May 2017 Published: 04 December 2017