Judul: Antimicrobial Activity of Sponge-Haliclona sp.-Associated Bacteria and Their Genetics Analysis
Abstrak: Three marine bacterial isolates isolated from sponge-Haliclona sp. coded as HAL-13, HAL-74, and HAA-01 produced broad spectrum of antimicrobial compounds. Extraction of antimicrobial compounds has been performed using n-butanol and ethyl acetate solvent. Bacterial crude extracts from all of these isolates showed broad spectrum activity against bacterial and fungal test strains, i.e. Staphylococcus aureus, Pseudomonas aeroginosa, enteropathogenic Escherichia coli K1-1, Candida albicans, and Candida tropicalis. Crude extract from HAL-13 showed the highest antimicrobial activity against bacterial and fungal test strain. Analysis of active spot from thin layer chromatography plate was conducted by bioautography technique. At least one spot from each bacterial crude extract has antimicrobial activity against Staphylococcus aureus and enteropathogenic Escherichia coli K1-1. Purification of antimicrobial compounds from HAL-13 were performed using column chromatography with chloroform-methanol solvent system. Thirty-seven fractions were collected from column chromatography, five fractions of which have antimicrobial activity. DNA fragment of ketosynthase of polyketide synthase genes cluster from HAL-13, HAL-74, HAA-01 were amplified and successfully cloned into pGEMT-Easy. Sequences analysis showed that they had homology with PKS type of 1 B. subtilis BSN5 for HAL 13 and HAA-01, and PKS type 1 of B. amyloliquefaciens for HAL-74.
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Judul: Analysis of bioactive compounds as wide Spectrum antimiccrobial from sponge associated bacteria from Haliclona sp.
Abstrak: Senyawa antimikrob berspektrum luas dari enam isolat yang berasosiasi dengan spons Haliclona sp. diekstrak menggunakan pelarut etil asetat. Keenam isolat tersebut adalah HAA-02, HAA-07, HAL-08, HAL-10, HAL-20, dan HAL-23. Ekstrak kasar bakteri tersebut kemudian diuji aktivitasnya terhadap beberapa mikrob patogen dan non patogen. Hasilnya sebagian ekstrak kasar isolat bakteri marin tersebut memiliki aktivitas hambatan terhadap S. aureus, EPEC, B. subtilis, E. coli, P. aeruginosa, dan C. albicans. Konsentrasi hambatan minimum (MIC) dari supernatan bakteri marin tersebut berkisar antara 12,5% hingga 100%. Hasil kromatografi lapis tipis dibawah sinar UV 365 nm menunjukkan bahwa masing-masing isolat bakteri marin memiliki fraksi yang aktif menghambat P. aeruginosa melalui uji bioautografi. Dua dari enam isolat membawa gen poliketida synthase (PKS) dan lima dari enam isolat membawa gen nonribosomal peptide syntethase (NRPS).
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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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