KAJIAN ENZIM XILANOLITIK JAMUR TANAH DAN APLIKASINYA SEBAGAI AGEN PEMUTIH PULP

ELISA NURNAWATI, S.SI., M.SI., Prof. Dr. Ir. Sebastian Margino, Prof. Dr. Ir. Erni Martani; Dr. Ir. Sarto

2015 | Disertasi | S3 Bioteknologi

Penelitian mengenai kajian enzim xilanolitik jamur tanah dan aplikasinya sebagai agen pemutih pulp (bubur kertas) ini bertujuan untuk memperoleh strain jamur indigenous penghasil xilanase dari tanah yang mempunyai potensi untuk diaplikasikan di industri pulp dan kertas. Xilanase jamur diproduksi secara ekstraseluler. Xilanase dengan aktivitas tinggi dalam pH alkali berpotensi digunakan dalam industri pulp dan kertas. Isolasi jamur dilakukan untuk mendapatkan isolat jamur netral dan alkalitoleran. Sebanyak 199 isolat, dengan perincian 111 isolat jamur netral dan 80 isolat jamur alkali, diperoleh dari sumber isolat yang berasal dari tanah hutan, tanah penggergajian kayu, tanah sekitar industri pulp dan kertas dan tanah pengolahan sampah. Berdasarkan seleksi pada media agar yang mengandung 1% birchwood xylan, sebanyak 51 isolat jamur menunjukkan kemampuan xilanolitik lebih baik dibandingkan isolat lainnya. Seleksi dalam media cair menghasilkan 2 isolat dengan aktivitas xilanase tertinggi yaitu N17BDSM yang merupakan isolat jamur netral dan isolat jamur alkalitoleran A10WNGM. Aktivitas xilanase N17BDSM dan A10WNGM masing-masing adalah sebesar 5,294 U/mL dan 3,753 U/mL. Identifikasi jamur berdasarkan karakter fenotipik dan genotipik menunjukkan bahwa isolat N17BDSM adalah Chaetomium globosum, sedangkan isolat A10WNGM adalah Acremonium sclerotigenum. Hasil optimasi kondisi fermentasi produksi xilanase oleh Chaetomium globosum 17BDSM adalah pH 7, suhu ruang (28 - 30°C), sumber karbon adalah xilan dengan konsentrasi 1%, konsentrasi inokulum 10% pada kerapatan propagul 108/mL, kecepatan agitasi 150 rpm dan 6 hari inkubasi. Produksi xilanase dengan aktivitas tinggi oleh Acremonium sclerotigenum 10WNGM adalah pH 9, suhu ruang (28 - 30°C), sumber karbon adalah xilan dengan konsentrasi 1%, konsentrasi inokulum 10% pada kerapatan propagul 108/mL, kecepatan agitasi 150 rpm dan 7 hari inkubasi. Xilanase Chaetomium globosum 17BDSM mempunyai berat molekul 24,208 kDa, pH optimum 6,2, suhu optimum 45°C, Km 15,636 mg/mL dengan Vmaks adalah 90,909 μmol/mL/menit. Xilanase Acremonium sclerotigenum 10WNGM mempunyai berat molekul 28,187 kDa, pH optimum 8,6, suhu optimum 50°C, Km 15,643 mg/mL dengan Vmaks adalah 71,429 μmol/mL/menit. Penurunan bilangan Kappa pada proses pre-treatment menggunakan xilanase berkisar antara 14,51 – 18,52% dibandingkan dengan kontrol dan mampu meningkatkan derajat putih kertas. Dengan demikian, isolat jamur indigenous penghasil xilanase telah berhasil diperoleh dan mempunyai potensi untuk diaplikasikan dalam industri pulp dan kertas. Kata kunci : jamur tanah, xilanase, optimasi kondisi fermentasi, pemutihan pulp

The study of xylanolytic soil fungi and its application as pulp bleaching agent was conducted to obtain the best indigenous xylanolytic soil fungi that potentially to be applied in the pulp and paper industry. Fungi produce extracellular xylanase. High activity xylanase in alkaline condition could potentially be used in the pulp and paper industry as agent of prebleaching agent pulp. Fungal isolation was done to obtain neutral and alkalitolerant fungal isolate. As many as 199 isolates, consisting of 111 neutral isolates and the other were alkaline isolates, were collected from several sources isolates from forest soil, sawmill soil, soil surrounding the pulp and paper industry and processing of waste. Based on xilanolytic activity on agar medium containing 1% birchwood xylan, 51 fungal isolates showed better results than the other isolates. Screening in liquid medium was obtained two fungal isolates showed the highest activities which were neutral fungal isolates N17BDSM and alkalitoleran isolates A10WNGM. The activity of xylanase N17BDSM was 5.294 U/mL, whereas the specific activity A10WNGM was 3.753 U/mL. Both fungal isolates were identified based on phenotypic and genotypic characters, showed that fungal isolates N17BDSM was Chaetomium globosum, whereas isolates of A10WNGM was Acremonium sclerotigenum. The result of optimization of fermentation condition of xylanase production by Chaetomium globosum 17BDSM was pH 7 at room temperature (28 - 30°C), carbon source was 1 % xylan, 10 % inoculums concentration on the density of 108 propagules/mL, agitation speed of 150 rpm and 6 days of incubation. High activity xylanase by Acremonium sclerotigenum 10WNGM was reached on pH 9 at room temperature (28 - 30°C), carbon source was 1 % xylan, inoculums concentration was 10 % on propagules density of 108/mL, agitation speed of 150 rpm and 7 days of incubation. The molecular weight of partially purified xylanase of Chaetomium globosum 17BDSM was 24.208 kDa showing optimal activity at 45ºC and pH 6,2. The Km and Vmax values were 15.636 mg/mL and 90.909 mol/mL/min, respectively. Xylanase Acremonium sclerotigenum 10WNGM had a mass of about 28.187 kDa. The partially purified enzyme had a Km of 15.643 mg/mL and a Vmax of 71.429 μmol/mL/menit for birchwood xylan at 50°C and pH 8.6. The decrease of Kappa number in pre-treatment process using xylanase at around 14,51 – 18,52% was compared with control and could increase the brightness of pulp. Therefore, indigenous fungal isolates producing xylanase were successfully obtained and their xylanase potentially to be applied in pulp and paper industry. Keywords: soil fungi, xylanase, optimalization of fermentation, biobleaching pulp

Kata Kunci : jamur tanah, xilanase, optimasi kondisi fermentasi, pemutihan pulp; soil fungi, xylanase, optimalization of fermentation, biobleaching pulp