Judul: Isolasi Bakteri Termofil Penghasil Enzim Hidrolitik Ekstraseluler dari Sumber Air Panas Gunung Pancar
Abstrak: Delapan belas bakteri termofil aerob diisolasi dari sampel sumber air panas Gunung Pancar dengan kondisi kultivasi 70°C dan pH 7.5 pada media agar-agar Luria yang dimodifikasi (LA modifikasi). Isolat-isolat tersebut terdeteksi mempunyai aktivitas hidrolitik (proteolitik, amilolitik, kitinolitik, xilanolitik, dan lipolitik) terhadap makromolekul yang disuplementasikan pad a media LA modifikasi. Enam belas isolat tersebut menunjukkan ciri-ciri genus Bacillus, sedangkan dua isolat lainnya menunjukkan ciri-ciri Thermus. Aktivitas proteolitik dari empat isolat (GP-O I, GP-04, GI'-06, dan GI'-\ 0) tampak cukup besar pada media agar-agar susu skim. tetapi aktivitasnya rendah pada media cair, yakni hanya 0,05-0,37 unit per ml ekstrak kasar enzim. Suhu optimum aktivitas keempat protease tersebut ialah 70°C (GP-O \. GP-06, GP- 10) dan 80°C (GP- 04), sedangkan pH optimumnya ialah 7,5 (GP-O\. GI'-06, GP-IO) dan 8,5 (GP-04). Waktu paruh protease GP-04 dan GP-IO lebih dari 7,5 jam. pada suhu inkubasi 70°C. Amilase isolat GP-15 yang mirip dengan B-amilase beraktivitas optimum pada suhu 90°C, pH 8,5, dengan waktu paruhnya lebih dari 7,5 jam pada suhu inkubasi 70°C.
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Judul: Isolasi dan Seleksi Bakteri Selulolitik Termofilik dari Kawah Air Panas Gunung Pancar, Bogor
Abstrak: Cellulase has important roles in paper, textile, food, and detergent industries. Application of cellulase in industries requires the cellulase to be active and stable at high temperature. Exploration of thermophilic bacteria from crater of hot spring is one of way to obtain thermostable cellulase. The aim of this research was to isolation thermophilic bacteria which has cellulolytic activity from White and Red Crater of Mount Pancar. Cellulolytic activity was determined by ability of bacteria to degrade carboxymethyl cellulose (CMC) substrate. Cellulolytic bacteria was selected based on clear zone which form surrounding the colonies. Cellulase activity was measured by dinitrosalisilic acid (DNS) method. Growth pattern of cellulolytic bacteria was determined. Results showed that bacterial isolates from White and Red Crater of Mount Pancar able to produce cellulase. There were 8 colonies (KP1, KP2, KP3, KP4, KP5, KP6, KP7, and KP10) from white crater and 1 colony (KM1) from red crater showing ability to degrade CMC. KP4 isolate had the higest diameter ratio of clear zone and enzyme activity ( 3.8 and 6.11 x 10-3 U/mL) than KM1 isolate (1.7 and 1.17 x 10-3 U/mL). Both isolates had same growth pattern.
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Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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