Judul: Karakterisasi Morfologi Sel dan Penapisan Aktivitas Hidrolisis dari Isolat Bakteri Tanah Pulau Muna, Sulawesi Tenggara
Abstrak: Bakteri penghasil enzim ekstraselular, khususnya enzim amilase, selulase, dan protease, dapat digunakan dalam berbagai industri. Lima belas isolat bakteri tanah yang diisolasi dari Pulau Muna, Sulawesi Tenggara, belum diketahui potensinya sebagai penghasil enzim-enzim tersebut. Penelitian ini bertujuan mengkarakterisasi morfologi sel dan menapis aktivitas amilolitik, proteolitik dan selulolitik dari bakteri tanah yang diisolasi dari Pulau Muna. Karakterisasi morfologi dilakukan dengan pewarnaan Gram. Penapisan bakteri dilakukan dengan metode kualitatif pada medium padat. Berdasarkan pengecatan Gram, 5 Isolat tergolong ke dalam bakteri Gram negatif dan 10 Isolat tergolong bakteri Gram positif, dengan bentuk sel yang bervariasi yaitu batang panjang dan bulat. Empat dari 15 isolat memiliki karakter hemolisis negatif atau gamma hemolisis sehingga diduga tidak bersifat patogen. Empat isolat tersebut selanjutnya digunakan untuk penapisan aktivitas hidrolisis terhadap amilum, selulosa, dan protein. Isolat M7 dan P7 mampu menghasilkan protease, selulase, dan amilase, sedangkan 2 isolat lainnya yaitu M4 dan P5 hanya mampu menghasilkan protease. Keempat bakteri tersebut dapat diteliti dan dikembangkan lebih lanjut sebagai penghasil enzim amilase, protease dan selulase., Bacteria producing extracellular enzymes, especially amylase, cellulase and protease enzymes, can be used in various industries. Fifteen isolates of soil bacteria isolated from Muna Island, Southeast Sulawesi, have no known potential as producers of these enzymes. This research aims to characterize cell morphology and screen the amylolytic, proteolytic and cellulolytic activities of soil bacteria isolated from Muna Island. Morphological characterization was carried out using Gram staining. Bacterial screening was carried out using qualitative methods on solid medium. Based on Gram staining, 5 isolates were classified as Gram negative bacteria and 10 isolates were classified as Gram positive bacteria, with varying cell shapes, namely long rods and round. Four of the 15 isolates had negative hemolysis or gamma hemolysis characteristics so they were suspected not to be pathogenic. The four isolates were then used to screen for hydrolysis activity on starch, cellulose and protein. Isolates M7 and P7 were able to produce protease, cellulase and amylase, while the other 2 isolates, namely M4 and P5, were only able to produce protease. These four bacteria can be researched and developed further as producers of amylase, protease and cellulase enzymes
Keyword: Amilase, hemolisis, indeks hidrolitik, Protease, Selulase

Judul: Aktivitas Antibakteri dari Bakteri Tanah Asal Pulau Muna, Sulawesi Tenggara terhadap Bakteri Resistan Antibiotik
Abstrak: Eksplorasi bakteri tanah penghasil senyawa antibakteri perlu dilakukan untuk mengatasi permasalahan resistansi bakteri patogen terhadap berbagai antibiotik. Tanah di Pulau Muna, Sulawesi Tenggara dianggap sebagai lingkungan yang menjanjikan untuk mengisolasi bakteri yang mampu menghasilkan senyawa antibakteri. Selain itu, riset terkait keragaman dan bioprospeksi bakteri asal pulau ini belum pernah dilaporkan. Penelitian ini bertujuan mengevaluasi aktivitas antibakteri bakteri tanah yang diisolasi dari Pulau Muna terhadap bakteri multidrug-resistant (MDR) dan mendeteksi potensi produksi senyawa bioaktifnya melalui deteksi gen. Pada penelitian sebelumnya, 15 isolat bakteri tanah telah berhasil diisolasi dari tanah Pulau Muna. Uji antagonis menunjukkan sebanyak 5 dari 15 isolat bakteri tanah memiliki spektrum aktivitas antibakteri yang berbeda terhadap lima strain bakteri target MDR. Berdasarkan uji cakram, ekstrak kasar dari dua isolat paling potensial, yaitu kode M7 dan P1, dapat menghambat pertumbuhan kelima bakteri target pada konsentrasi 80 mg/mL. Nilai minimum inhibitory concentration (MIC) dan minimum bactericidal concentration (MBC) kedua ekstrak berkisar antara 312,5–>10.000 μg/mL. Identifikasi berdasarkan sekuens gen 16S rRNA menunjukkan kekerabatan tertinggi (kemiripan >97%) isolat M7 dan P1 dengan Priestia (Bacillus) aryabhattai strain B8W22 dan Bacillus aerius strain 24K. Kedua isolat tersebut terdeteksi memiliki gen MlnA yang terlibat dalam biosintesis macrolactin. Bakteri tanah ini dapat diteliti lebih lanjut untuk dikembangkan sebagai sumber antibiotik baru., Exploration of soil bacteria producing antibacterial compounds is required to overcome the problem of pathogenic bacteria’s resistance to various antibiotics. The soil of Muna Island, Southeast Sulawesi, is considered a promising environment to isolate bacteria capable of producing antibacterial compounds. This study aimed to evaluate the antibacterial activity of soil bacteria isolated from Muna Island against multidrug-resistant (MDR) strains and to detect the potential production of bioactive compounds through gene detection. Antagonism assay showed that 5 out of 15 soil bacterial isolates exhibited various spectra of antibacterial activity against five MDR strains. According to the disc diffusion assay, the crude extracts derived from two most potential isolates, namely M7 and P1, inhibit the growth of the five MDR strains at a concentration of 80 mg/mL. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of both extracts ranged from 312,5 to >10.000 μg/mL. Based on the 16S rRNA sequences, M7 and P1 isolates were closely similar (similarity >97%) to Priestia (Bacillus) aryabhattai strain B8W22 and Bacillus aerius strain 24K, respectively. Both isolates were detected to have the MlnA gene which involved in the biosynthesis of macrolactin. These soil bacteria could be further studied and developed as a new source of antibiotics.
Keyword: 16S rRNA, antibacterial, MIC, multidrug-resistant bacteria, soil bacteria

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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