PENAPISAN BAKTERI HALOFILIK PENGHASIL PROTEASE ASAL BLEDUG KUWU DAN KARAKTERISASI PROTEASE EKSTRASELULARNYA

YOHANNA ANISA I, M. Saifur Rohman, S.P., M.Eng., Ph.D.

2013 | Skripsi | MIKROBIOLOGI PERTANIAN

Bakteri halofilik merupakan salah satu kelompok mikroorganisme yang potensial sebagai penghasil enzim yang bersifat stabil pada kondisi ekstrim. Penelitian ini bertujuan untuk melakukan penapisan terhadap bakteri halofilik penghasil protease asal Bledug Kuwu serta mengetahui aktivitas dan karakter ekstraselular protease bakteri halofilik tersebut. Penapisan terhadap bakteri penghasil protease dilakukan menggunakan medium minimal padat air laut buatan yang mengandung 1% skim milk. Aktivitas proteolitik ditunjukkan dengan adanya zona jernih di sekitar koloni. Sebanyak 19 isolat berhasil diisolasi dari Bledug Kuwu, 4 isolat di antaranya [BKL-1(A), BKL-4(B), BKL-5(B), dan L(C2)] memiliki aktivitas proteolitik relatif tinggi dibandingkan isolat-isolat lainnya. Pengujian lebih lanjut dilakukan terhadap ekstrak kasar protease ke-4 isolat terpilih. Karakterisasi protease ekstraselular meliputi pengujian aktivitas enzim secara kuantitatif pada berbagai kadar garam, variasi suhu, serta pH. Protease ekstraselular isolat BKL-1(A) memiliki aktivitas optimal pada kadar garam 25%, suhu 35 o -55 o C, serta pH 7; BKL-4(B) pada kadar garam 5-15%, suhu 35 o -55 o C, dan pH 10; BKL-5(B) pada kadar garam 5-15%, suhu 65 o C, pH 9; serta L(C2) pada kadar garam 15%, suhu 35 o -55 o C, dan pH 8. Ekstrak kasar protease ekstraselular yang dihasilkan oleh ke-4 isolat tersebut berpotensi untuk dimanfaatkan secara luas, terutama pada proses-proses yang melibatkan kadar garam, pH netral sampai basa, ataupun suhu relatif tinggi (seperti pada industri deterjen atau penyamakan kulit), di mana kebanyakan protease menurun aktivitasnya.

Halophilic bacteria are potential microbes for producing enzyme having high stability in extreme environments. The objective of this research was to select protease producing halophilic bacteria from Bledug Kuwu and characterize its extracellular protease. Proteolytic activity of halophilic bacteria was examined on agar medium containing 1% of skim milk. Colonies surrounded by the clear zone were considered as positives colonies. In this work, 19 bacterial isolates were tested for proteolytic activity. Four out of the 19 bacterial isolates, BKL-1(A), BKL-4(B), BKL-5(B), dan L(C2), showed the highest proteolytic activity and were selected for further analyses. Protease activity was assessed quantitatively in various concentrations of NaCl, temperature, and pH. Extracellular protease from BKL-1(A) exhibited optimum activity in the presence of 25% of salt, temperature 35 o -55 o C, and pH 7. BKL-4(B) has extracellular protease with optimum activity in the presence of 5-15% of salt, temperature 35 o -55 o C, and pH 10. Extracellular protease from BKL-5(B) exhibited optimum activity at 5-15% of salt, 65 o C, and pH 9; while L(C2) has extracellular protease with optimum activity in the presence of 15% of salt, 35 o -55 o C, and pH 8. These results suggested that the four selected isolates were able to produce extracellular proteases having remarkable potential to be applied in industrial processes in which extreme temperature, pH, and various ranges of salt concentration are required (for example : in leather and detergent industry).

Kata Kunci : Bledug Kuwu, bakteri halofilik, protease ekstraselular