Judul: Karakterisasi Bakteri Asam Laktat Termofilik dari Kawah Putih Gunung Pancar, Bogor
Abstrak: Lactic acid bacteria (LAB) commonly found in fermented dairy products are known to have advantageous effects for health. Thus, they can add the value of milk based products, such as yoghurt, cheese, and kefir. The aim of the study was to characterize thermophilic LAB on its ability to carry out metabolism at high temperature. Exploration of this bacteria was carried out at extreme environment of Indonesia as habitat for thermophilic, the White Crater of Mount Pancar, Bogor. Characterization of thermophilic LAB was conducted at pH of 3, 5, 7, and 9 with variation temperature at 30ºC, 45ºC, 60ºC, and 75ºC. Quantitative determination of bacteria was based on turbidimetry method, Plate Count, and analysis on ability of acid production in milk medium under optimum conditions at 45˚C and 60˚C for 60 hours with 12 hours intervals. Results showed that thermophilic LAB has optimum condition at pH 7 with incubation temperature between 45˚C-60˚C, and incubation period at the optimum number of cell was about 20 hours. The ability of acid production in milk medium at 45˚C-60˚C was 0.16%-0.27% after 12-24 hours. The study showed that there was thermophilic LAB present in the local environment and needs further identification.
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Judul: Identifikasi Dan Karakterisasi Substrat Antimikroba Dari Bakteri Asam Laktat Kandidat Probiotik Yang Diisolasi Dari Dadiah Dan Yogurt
Abstrak: Probiotic has been defined as living microorganism that, when administered in adequate of amounts, confered a health benefit on the host. One of criterias that must be fulfilled by lactic acid bacteria as a probiotic is its ability to produce antimicrobial compounds that were capable inhibit toward pathogenic bacterias. Lactic acid bacteria (LAB) can be isolated from fermented milk. Maheswari (2008) isolated Lactobacillus plantarum D-01 and Lactococcus lactis D-01 from buffalo milk fermented called ‘dadiah’ traditionally produced by people from West and North Sumatra, and also isolated Bifidobacterium longum Y-01 and Lactobacillus acidophilus Y-01 from yogurt. Their potential as probiotic culture was interested to determine especially for their ability to produce antimicrobial substrate that inhibit pathogenic bacterias. Identification of nature and characterization of antimicrobial substrate produce by LABs tested for its stability at different pH and storage’s temperature, and proteolitic’s enzyme by agar well diffusion method. The culture supernatants inhibited toward Salmonella Ser. Typhimurium ATCC 14028, Escherichia coli ATCC 25922, and Staphylococcus aureus ATCC 25923. The supernatants showed an antimicrobial activity against phatogenic bacteria and identified as organic acid and hydrogen peroxide. The existance of proteinaceous antibacterial compound, which referred as bacteriosin, was proved through proteolityc activity on supernatants that resulted in decrease of zone inhibition diameters. Characterization determined that proteinaceous antibacterial compound was stable at room storage temperature within five days and at cold storage temperature within two weeks. Meanwhile, proteinaceous antibacterial compounds were not heat stable and not stable when adjusted in different pH, especially when adjusted in pH above 5. Four LABs tested could be considered as probiotic bacterias because all of LABs produced antimicrobial compounds consist of organic acid, hydrogen peroxide and bacteriosin that inhibited pathogenic indicator bacterias.
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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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