Penelitian bertujuan untuk mengetahui pengaruh metode freezing (-4oC) terhadap kadar klorofil dan protein pada 13 strain Nostoc koleksi Laboratorium Taksonomi Tumbuhan, Departemen Biologi FMIPA UI. Protektan DMSO 5% digunakan sebagai medium preservasi pada perlakuan, dan pada kontrol digunakan medium cair BG 11 N-free. Pengaruh metode freezing diketahui dengan membandingkan kadar klorofil dan protein pada sebelum dan sesudah preservasi (hari ke-0, hari ke-1, dan hari ke-7).Hasil penelitian menunjukkan bahwa kadar klorofil dan protein pada kelompok perlakuan lebih besar daripada kontrol. Tiga dari tiga belas strain (23,08 %) mengalami penurunan kadar klorofil sebesar 7,32% -- 47,02% setelah preservasi, sedangkan lima dari tiga belas strain (38,46%) mengalami penurunan kadar protein sebesar 7,69%--37,5% setelah freezing.

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The purpose of this study was to assess the effect of freezing method (-4oC) on chlorophyll and protein content of 13 Nostoc strains Culture Collection of Plant Taxonomy Laboratory FMIPA UI. The protectan used DMSO 5%, and liquid BG 11 N-free medium was used as control. The effect of freezing was evaluated by comparing the content of chlorophyll and protein of Nostoc before and after preservation (day-0, day-1, and day-7).

The result showed that the control had lower chlorophyll and protein content than the treatment. The chlorophyll content of three strains (23,08%) decreased about 7,32% -- 47,02% after freezing treatment, while the protein content of five strains (38,46%) decreased about7,69% -- 37,5%.