Judul: Analisis keragaman genetik dan sintasan sejumlah isolat bekteri fotosintetik anoksigenik asal laut
Abstrak: Eighty isolates of anoxygenic photosynthetic bacte- ria were isolated from 49 samples collected from a number of Indonesian seashores. All of the isolates showed similar color (i.e. photosynthetically in red to brownish red) when grown Sea Water Complete (SWC) medium. under illumination of tungsten light (± 200 lux). Many of the isolates were gram-negative, rod shape bacteria. However, genetic analysis employing Asel-schizotyping of 45 selected isolates indicated extensive genetic diversi- ty which apparently did not show any biogeographic relat- edness. A number their survival of selected isolates in sterile sea water were examined for supplemented with peptone (0,1 g/1) and yeast extract (0,02 g/1). All of the isolates demonstrated significant growth until 5 days of incubation and most of them maintained their viability up to 7 days of incubation. However, SKX121 is the only isolate which could maintain its viability up to 2 x 109 cell/ml after 7 days of incubation. From 47 isolates examined, 35 isolates were signifi- cantly more tolerant to Na2S (up to 100 µg/ml than isolate MW4, a reference isolate which has been known as sulphide tolerant anoxygenic photosynthetic bacteria.
Keyword: keragaman genetik, Bakteri fotosintetik, laut

Judul: Identification of Bacterial Isolates IR5 and IR9,  Relationships, Optimization of Media, and Synthesized Pigments
Abstrak: Bakteri isolat IR9 dan IR5 merupakan bakteri fotosintetik ungu yang biasa ditemukan di laut dan diketahui dapat menghasilkan pigmen. Isolat IR5 dan IR9 telah berhasil diisolasi dari laut. Penelitian ini bertujuan menganalisis kekerabatan antar kedua isolat tersebut berdasarkan sekuens 16S rRNA, mengoptimasi media pertumbuhan, dan mengidentifikasi jenis pigmen yang dihasilkan oleh kedua isolat tersebut. Analisis kekerabatan kedua isolat berdasarkan kemiripan sekuens 16S rRNA menunjukkan isolat IR5 dan IR9 tergolong ke dalam spesies Rhodovulum sulfidophilum. Kedua isolat tersebut diduga merupakan strain yang berbeda. Berdasarkan pengamatan secara kualitatif pada tingkat kepekatan warna kultur, isolat IR9 memiliki pertumbuhan yang lebih baik apabila dibandingkan dengan isolat IR5 pada media pertumbuhan yang sama. Komposisi media pertumbuhan yang paling optimum dan direkomendasikan untuk pertumbuhan isolat IR5 dan IR9 adalah 1% gula pasir + 0,5% NPK + 2,5% NaCl kasar. Media yang mengandung NPK mendukung pertumbuhan bakteri yang lebih optimum dibandingkan dengan media yang mengandung TSP tanpa NPK. Isolat bakteri IR9 mengalami pertumbuhan optimum pada hari ke-3. Identifikasi berdasarkan serapan panjang gelombang pada spektrofotometer UV-VIS menunjukkan bakteri tersebut mampu menghasilkan beberapa jenis pigmen, yaitu bacteriopheophytin, β-carotene, canthaxanthin, dan bacteriochlorophyll a.
Keyword: Identifikasi pigmen, kurva tumbuh, optimasi media, pohon filogenetik Rhodovulum sulfidophilum, Identifikasi pigmen, kurva tumbuh, optimasi media, pohon filogenetik Rhodovulum sulfidophilum

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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