Xylanase is an important hydrolytic enzymes with many application in several industries, but to obtain enzyme derived products is not easy. Thus, the optimization of efficient xylanases production is a great interest for biotechnological application. This study aims to determine the type of substrate, medium composition, and optimum conditions of xylanase production by S. costaricanus 45I-3. Determination of substrate type was done by growing the tested bacteria on birchwood xylan, beechwood xylan, oat spelled xylan, corn cobs xylan, and tobacco xylan substrate, meanwhile the determination of medium composition and enzyme production were done by measuring xylanase activity at various substrate concentration and replacing the carbon, nitrogen, phosphate and surfactants source. The results showed that the highest enzymatic index (EI) produced from corn cob xylan substrate at 3.60 meanwhile the second highest was beechwood xylan substrate at 2.87 EI, however this substrate is purer, thus this substrate was selected and used as xylan sources for further optimization measurement. The best xylanase activity (2.29 U/mL) obtained on eighth day after inoculation on rotary incubator at 120 rpm in 28 ºC. Arabinose as the source of carbon generate the highest activity at 3.161 U/mL meanwhile the most preferred source of phosphate is Na2HPO4 (2.37 U/mL). Both source of nitrogen i.e. nitrogen ammonium sulphate (NH4)2SO4 and yeast extract were able to produce xylanase at 2.57 and 2.36 U/mL. The addition of surfactant in production medium showed addition of SDS surfactant (0.146 U/mL) and Tween 80 (0.438 U/mL) showed a negative response by decreasing the activity. The conclusion showed that the xylanase activity was increased after optimization at various C, N, and P sources, and the use of nitrogen source (NH4)2SO4), become a more economical alternative to replacing a nitrogen source yeast extract so it can lower the production costs of xylanase enzyme.

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ABSTRAKMetode ekstraksi peptida terlarut pada produk kedelai dan fermentasi kedelai sangat bervariasi. Penelitian ini dilakukan untuk menganalisa sifat kelarutan peptida dengan berat molekul kecil pada sampel tempe yang diambil dari dua jenis kedelai (GMO dan non-GMO) serta dua jenis perlakuan (perebusan dan tanpa perebusan) yang berbeda. Pelarut yang digunakan meliputi air dan pelarut organik yang umum digunakan dalam ekstraksi peptida kedelai dan produk memberikan tingkat kelarutan peptida tempe kedelai lebih baik dibanding pelarut air (p < 0,05). Penambahan asam peptida terlarut hingga 1,522 mM (31,7%). Tempe GMO menunjukkan kelarutan peptida lebih tinggi dibanding non-GMO sedangkan proses perebusan juga diketahui mempunyai tingkat kelarutan yang lebih tinggi dibanding tempe tanpa perebusan.Kata kunci: Asetonitrile; kelarutan; peptida; tempe; ABSTRACTThere are various methods exist to extract soluble peptide from soybean and its fermented products. This study was aimed to evaluate the solubility of low molecular weight peptide of tempe from two types of bean (GMO and non-GMO soybean) and two different treatment (boiling and non-boiling). The solvents used were water and organic solvents which commonly used as solvents for soy-fermented product. The result showed that acetonitrile (A): water (W): p < 0.05). The addition of GMO tempe showed the higher content of peptide recovery compared with non-GMO tempe, while boiled tempe also gave higher peptide recovery than non-boiled tempe. Keywords PENDAHULUANTempe merupakan salah satu pangan produk fermentasi kedelai (Glycine max L.) berasal dari Indonesia yang saat ini sudah dikenal luas didunia. Pada perkembangannya, tempe bisa diproduksi menggunakan berbagai jenis kacang seperti kacang koro benguk (Mucuna pruriens L.D.C. var. utilis), gude (Cajanus cajan), lupin (Lupinus angustifolius), kacang merah (Phaseolus vulgaris) dan jenis lainnya, namun kedelai merupakan jenis bahan baku yang paling populer dikarenakan

Chitinolytic actinobacteria are currently more widely used because of their ability as the biological control agents to the pathogenic fungi, especially in horticultural and plantation crops. This research was conducted to obtain isolates of chitinolytic soil actinobacteria from the rhizosphere of the rubber plant (Hevea brasiliensis) area in IPB University. Antifungal activities from these actinobacteria hopely able to inhibit the growth of plant pathogenic fungi in Vitro on chitin agar media. Fusarium oxysporum and Sclerotium rolfsii are used in the inhibition test of chitinolytic actinobacteria. The results successfully obtained 16 isolates of actinobacteria were grew on  Humic Acid Vitamin (HV) agar. It showed that six of 16 actinobacteria isolates were able to produce inhibition zones to the growth of hyphae of pathogenic fungi on potato dextrose agar (PDA). KK-15 and KK-07 isolates were able to produce the largest inhibition percentages in F. oxysporum and S. rolfsii. Based on the chitinolytic index (CI) values, KK-15 and KK-07 isolates produced CI values of 1.25 and 1.5, respectively. The morphological characteristics and Gram staining of both KK-15 and KK-07 isolates are closely relative with Streptomyces sp. Abstrak: Bakteri kitinolitik saat ini banyak diteliti karena kemampuannya sebagai agens pengendali hayati jamur patogen khususnya pada tanaman hortikultura dan perkebunan. Penelitian ini dilakukan untuk mendapatkan isolat-isolat bakteri kitinolitik asal tanah dari bagian perakaran tanaman karet (Hevea brasiliensis) di daerah perkebunan karet Institut Pertanian Bogor (IPB). Aktivitas antifungi dari bakteri ini diharapkan  mampu menghambat pertumbuhan jamur patogen tanaman secara in Vitro pada media agar-agar kitin. Fusarium oxysporum dan Sclerotium rolfsii digunakan dalam uji hambat aktinobakteri kitinolitik. Hasil penelitian memperoleh 16 isolat aktinobakteri berhasil diisolasi dengan menggunakan media agar-agar Humic Acid Vitamin (HV), dan dari 16 isolat tersebut, enam isolat mampu menghasilkan zona hambat terhadap pertumbuhan hifa dari kedua jamur patogen pada media Potato Dextrose Agar (PDA) secara in Vitro. Isolat KK-15 dan KK-07 mampu menghasilkan diameter hambatan terbesar pada jamur F. oxysporum dan S. rolfsii. Berdasarkan nilai index kitinolitik (IK), isolat KK-15 dan KK-07 menghasilkan nilai IK sebesar 1,25 dan 1,5 secara berurutan. Karakteristik morfologi dan pewarnaan Gram dari kedua isolat yaitu KK-15 dan KK-07 memiliki kedekatan dengan kelompok Streptomyces spp.