Judul: Penapisan bakteri Xilanolitik dan karakterisasi Xilanasenya untuk hidrolisis tongkol jagung
Abstrak: Hemicellulose is the second largest polysaccharide in nature after cellulose, which consists of xylan as main component. Xylanolitic bacteria produce extracellular enzymes that could hydrolyze agricultural waste, especially xylan-rich materials to xylose and xylooligosaccharides. This research is aimed to screen local isolate xylanolitic bacteria and characterize its enzyme, and then utilize the enzyme for corncob hydrolysis. Seven bacteria isolates (isolates C, F, G, H, J, K1, and P) were selected in this research for its capability to hydrolyze xylan qualitatively and produced high activity enzymes. Enzyme from selected isolate was characterized its optimum pH, substrate specifity, and its stability, and applied it as biocatalyst for corncob hydrolysis. Isolate P was selected as produced high activity enzyme (17.465 nkat/ml) after 7 days fermentation. The enzyme has highest activity on pH 8, corncob as substrate, and stable on temperature of 30oC for 12 hours. Products from enzymatic hydrolysis of corncob after 12 hours were oligosaccharides with DP around 7.
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Judul: Produksi xilooligozakarida dari xilan tongkol jagung dengan menggunakan xilanase streptomyces sp asal Indonesia
Abstrak: Production of xylanase from three local isolates could be induced with xylan from corncob. The strains of Streptomyces sp. which used in this research are 234P-16 strain, SKK1-8 strain, and 45I-3 strain. Xylanases from strain SKK1-8 and strain 45I-3 showed the higher activity with corncob xylan than oatspelt xylan. The highest xylanase activities for three strains produced from corncob xylan substrate with 1% concentration than 0.5% and 1.5%. Xylanase which produced by Streptomyces sp. is used for hydrolyzing xylan to produce xylooligosaccharide. The product of xylanase hydrolysis could be determined by reducing analysis sugar determination, changing of carbohydrate degree of polymerization (DP), and by Thin Layer Chromatography (TLC). Xylan hydrolysis product from 234P-16 xylanase was long chain xilooligosaccharide on oatspelt xylan and corncob xylan with DP ranging from 83.13 to 20.24. Xylan hydrolysis product SKK1-8 xylanases was short chain xilooligosaccharide with DP ranging from 12.01 to 2.12, and from 45I-3 DP ranging from 5.75 to 2.12 on oatspelt xylan and corncob xylan. The TLC chromatogram showed that hydrolysis product contains various xylooligosaccharides.
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Judul: Peramalan Curah Hujan dengan Model ARIMA (Autoregressive Integrated Moving Average) dan VECM (Vector Error Correction Model).
Abstrak: Peramalan curah hujan diperlukan untuk memprediksi curah hujan pada periode berikutnya. Penelitian ini menggunakan 2 (dua) model peramalan yaitu model ARIMA (Autoregressive Integrated Moving Average) dan VECM (Vector Error Correction Model). ARIMA merupakan model peramalan yang berdasarkan pada data deret waktu peubah amatan itu sendiri sebagai pembentuk modelnya. VECM merupakan model peramalan yang melibatkan 1 (satu) atau lebih data deret waktu peubah penjelas sebagai pembentuk modelnya. Berdasarkan model ARIMA, model yang terpilih sebagai model terbaik adalah ARIMA (1, 1, 2). Validasi model dari data pengujian pada model ARIMA (1, 1, 2) berdasarkan MAD dan RMSE sebesar 14.06 dan 17.29. Pada VECM, peubah penjelas yang digunakan yakni suhu, kelembaban, dan lama penyinaran. Berdasarkan VECM (1) yang diperoleh, terdapat dua hubungan terhadap perubahan curah hujan, yakni hubungan jangka panjang dan jangka pendek. Pada hubungan jangka panjang, perubahan curah hujan dipengaruhi oleh curah hujan dan lama penyinaran masing-masing 1 (satu) periode sebelumnya. Pada hubungan jangka pendek, perubahan curah hujan hanya dipengaruhi oleh perubahan lama penyinaran 1 (satu) periode sebelumnya. Validasi VECM (1) dari data pengujian berdasarkan MAD dan RMSE sebesar 13.46 dan 16.81. Sehingga pada penelitian ini, VECM (1) dapat lebih baik meramalkan curah hujan dibanding model ARIMA (1, 1, 2).
Keyword: curah hujan, model ARIMA, VECM