Isolation of Corncob Xylan-Degrading Fungi and Its Application in Xylobiose Production

TANTRY FEBRINASARI, Dr. Ir. Muhammad Nur Cahyanto, M.Sc.; Prof. Takata Goro

2019 | Tesis | MAGISTER ILMU DAN TEKNOLOGI PANGAN

Penelitian ini berhasil mengisolasi dan menskrining isolat jamur potensial pendegradasi xilan tongkol jagung yang diidentifikasi sebagai Fusarium oxysporum (HM210091.1). Produksi xilanase oleh F. oxysporum melalui fermentasi substrat padat dengan menggunakan tongkol jagung sebagai substratnya mampu menghasilkan aktivitas xilanase maksimum pada kondisi ukuran partikel substrat 60 mesh, rasio kadar air 2 mL/g substrat, suhu inkubasi 30oC, pH awal 6, jumlah inokulum 5x107/3 g substrat, dan waktu inkubasi 2 hari. Aktivitas xilanase meningkat sekitar 4 kali hingga mencapai 7.92 U/mL setelah optimasi. Xilanase ekstrak kasar yang dimurnikan secara parsial melalui presipitasi amonium sulfat (30-70%) yang dilanjutkan dengan dialisis menghasilkan faktor pemurnian sebesar 1.64 kali lipat dan pemulihan sebesar 62.91%. Aktivitas relatif xilanase pada xilan tongkol jagung terhadap aktivitas xilanase pada xilan beechwood komersial adalah sebesar 37.58%. Xilanase memiliki aktivitas optimum pada pH 5.5 dan suhu 50oC, dan memiliki kestabilan paling tingi pada pH 6 dan suhu 30oC setelah 1 jam inkubasi pada pH dan suhu optimum. Proses hidrolisis xilan tongkol jagung dengan konsentrasi 6% oleh xilanase sebanyak 100 U/g substrat pada kondisi pH dan suhu optimum xylanase (pH 5.5 dan suhu 50oC) mampu menghasilkan xilobiosa sebesar 28.71 g/100 g xilan murni setelah 12 jam inkubasi. Proses pemurnian hidrolisat dapat mempertahankan 91.08% jumlah xilobiosa. Xilobiosa murni berhasil diperoleh melalui tahap separasi lebih lanjut dengan menggunakan kromatografi kolom arang aktif, namun pemulihannya hanya sebesar 59.29%.

In this present study, a potential corncob xylan-degrading fungal strain as xylanase producer was isolated and screened from soil, and identified as Fusarium oxysporum (HM210091.1). The production of xylanase by F. oxysporum under solid state fermentation using corncob powder as the solid substrate reached the maximum xylanase activity when using particle size of substrate of 60 mesh, water content ratio of 2 mL/g substrate, incubation temperature of 30oC, initial pH of 6, amount of inoculum of 5x107 spore/3 g substrate, and incubation time of 2 days. The xylanase activity increased about 4 times up to 7.92 U/mL after optimization. The crude xylanase was partially purified using ammonium sulphate precipitation (30-70%) followed by dialysis and resulting purification factor of 1.64 fold as well as yield of 62.91%. The relative activity of partial purified xylanase towards alkali-extracted corncob xylan was found 37.58% with respect to commercial beechwood xylan. The xylanase activity was optimum at pH 5.5 and temperature 50oC, and the most stable at pH 6 and temperature 30oC after 1 h incubation at optimum pH and temperature. The potential application of partial purified xylanase of F. oxysporum in hydrolyzing alkali-extracted corncob xylan to produce xylobiose was also demonstrated. Hydrolysis of 6% of corncob xylan using 100 U/g substrate of enzyme loading under optimum pH and temperature conditions (pH 5.5 and 50oC, respectively) achieved the yield of xylobiose up to 28.71 g/100 g pure xylan after 12 h incubation. The purification of hydrolysate could retain 91.08% of xylobiose. Further separation step using activated charcoal column chromatography was able to get a pure xylobiose, but could only recover 59.29% of xylobiose.

Kata Kunci : corncob, fungal strain, Fusarium oxysporum, isolation, solid state fermentation, xylan, xylanase, xylobiose, xylooligosaccharides