Judul: Keragaman Karakter Xilanase Dari  Tiga Isolat Streptomyces Asal Indonesia
Abstrak: Xilan is the major component of hemicellulose found in plant cell wall. The aboundance of xylan in nature suggested the importance of xylan bioconvertion by xylanases. Three isolates of Streptomyces from Indonesia respective to 45I-3, 234P-16, and SKK1-8 could produce extracelluler xylanases when grown in birchwood xylan medium. Stability test in optimum temperature showed that xylanases from 234P-16, SKK1-8, and 45I-3 have half life time 23 hour 9 minute, 1 hour 45 minute, and 2 hour 9 minute, respectively. Xylanases from three isolates were stable at temperature 3 oC. Xylanases from three isolates showed the highest activity at oatspelt xylan and the lowest at CMC. HPLC analysis showed that hydrolytic product of birchwood xylan especially are xylosa and arabinosa. Xylanases from three isolates could be precipitated by acetone. Zymogram analysis showed that three isolates could degrade birchwood xylan, and their molecular masses were estimated to be approximately 16.37 kDa, 14.39 kDa, and 12.65 kDa for 45I-3; 16.80 kDa and 14.76 kDa for 234P-16; and 16.80 kDa, 15.21 kDa, and 13.86 kDa for SKK1-8.
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Judul: Karakteristik Proses Pembentukan dan Produk Xilanase dari Isolat Streptomyces sp. Terpilih Menggunakan Substrat Limbah Pertanian
Abstrak: Empty Fruit Bunch (EFB) and bagasse are lignocellulosic waste which rich of xylan. It has not been utilized optimally. Xylanase is alternative of xylan degrading agent. The aim of this research was to find and get the excellent of xylanase producing isolate and get some of the characters from the formation process and product of xylanase obtained on the fermentation of agricultural wastes substrate such as EFB and bagasse. The screening was done by comparing the xylanolytic index of six Streptomyces sp. isolates. Crude xylanase was analyzed by many parameters (incubation time, molecular weight, and type). Streptomyces sp. (P3CCA13) isolate was selected isolates with an xylanolitic index 0.818 (beechwood xylan), 0.500 (EFB) and 0.384 (bagasse). The highest xylanase activity on EFB, beechwood xylan and bagasse substrates are at incubation time 120 hours (7.5092 U/mL), 144 hours (5.9831 U/mL), and 192 hours (5.6660 U/mL). Based on TLC chromatogram of its products, this xylanase was predicted as endoxylanase (Rf=0.7143). The molecular weight of this xylanase was estimated between 16 to 47 kDa.
Keyword: bagasse, EFB, xylan, xylanase, Streptomyces sp. (P3CCA13)

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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