Judul: Isolasi karakterisasi bakteri metanotrof asal sawah di Bogor dan Sukabumi
Abstrak: Sebesar 43% dari emisi metan (CH,) ke ahnosfer berasal dari lahan basah dan sawah. Peningkatan emisi satu molekul CH, berpotensi sebagai gas mmah kaca 20 kali lebih besar daripada satu molekul C02. Sebagian besar emisi CH4 di kawasan sawah yang tergenang diproduksi oleh bakteri metanogen dan sebanyak 80 % dari CH4 tersebut dioksidasi oleh bakteri metanotrof. Bakteri metanohof memiliki sistem enzim yang spesifik yaitu metan monooksigenase (MMO) yang mampu menambahkan satu atom oksigen ke dalam molekul CH4 untuk membentuk senyawa metanol. Aplikasi bakteri metanohof dapat mengurangi emisi metan dari lahan sawah. Ekplorasi bakteri metanohof dari contoh sedimen asal sawah di Bogor dan Sukabumi yang ditumbuhkan pada media Nitrat Mineral Salts (NMS) menghasilkan 40 isolat. Aktivitas oksidasi CH, diukur dengan menggunakan kromatografi gas, sedangkan aktivitas soluble rnethane monooxygenase (sMMO) diuji dengan metode kolorimehik. Enam isolat (BGM 1, BGM 2, BGM 3, BGM 12, SKM 14, BGM 9) dikarakterisasi aktivitas oksidasi metannya secara berkala. Aktivitas oksidasi CH4 tertinggi pada isolat BGM 9, yaitu sebesar 66556,82 moll hari. Aktivitas enzim sMMO teridentifikasi pada isolat BGM 9.
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Judul: Karakterisasi Fisiologi dan Identifikasi Molekuler Isolat-isolat Bakteri Metanotrof Asal Sawah Wilayah Bogor dan Sukabumi
Abstrak: Methane (CH4) is one of the main greenhouse gasses that could absorb infra-red radiation so it contribute to global warming. Methanotrophs are bacteria that are able to grow using methane as their only source of carbon and energy. They play a major role in the reduction of the release of methane into the atmosphere from environments. Methanotrophic bacteria isolated from Ricefields in Bogor and Sukabumi (BGM 1, BGM 2, BGM 3, BGM 9, and SKM 14) had a high methane oxidation. Activity physiologycal assay using API 20 NE and molecular identification using 16S rRNA gene sequence analysis were conducted in this research. Five isolates showed a positive reaction of physiological assays for gelatine, β-galactosidase enzyme, glucose assimilation, mannitol assimilation, N-asetil-glukosamin assimilation, maltose assimilation, and malic acid assimilation. BGM 1 and BGM 3 16S rRNA sequence showed that they had similarity to Methylocystis rosea into 74% and 70% respectively, while BGM 2 and BGM 9 had similarity to Methylococcus capsulatu into 83% and 85% respectively, and SKM 14 had 65% similarity with Methylobacter sp. Phylogenetic tree showed that BGM 1 and BGM 3 isolates were in the same group with Methylocystis rosea strain SV97T, Methylobacterium extorquens, and Methylosinus trichosporium, nevertheless they were very close related to Methylocystis rosea strain SV97T. BGM 2, BGM 9, and SKM 14 isolates were in the same group with Methylococcus capsulatus strain texas, Methylomicrobium buryatense, and Methylobacter sp. nevertheless BGM 2 and BGM 9 isolates were very close related to Methylococcus capsulatus strain texas. While SKM 14 was very close related with Methylobacter sp.
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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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