Judul: Isolasi dan Identifikasi Mikrob Tanah Pendegradasi Selulosa dan Pektin dari Rhizosfer Aquilaria malaccensis
Abstrak: Gaharu (agarwood) is one of non-timber forest product that has been used for thousand years by ancestors in religious rituals, as perfume, incense, fragrance, even for medicines. Gaharu can be found commonly from trees of genus Aquilaria. Scientists indicated various hypothesis to understand agarwood formation in the tree, one of them is pathological hypothesis. In pathological hypothesis, agarwood formation is caused by microbial infection inside plant tissue host. The presence of pathogen attack will make the host to produce phytoalexins as self defence. Thus, it is estimated that agarwood formation conducted by accumulation of phytoalexins in damage plant tissues. This research aims to explore soil microbes in rhizosphere of Aquilaria malaccensis which have ability to degrade cellulose and pectin. Screening was conducted to observe cellulase and pectinase activities. Isolates were screened in selective media, namely CMC (carboxymethyl cellulose), CPAF (citrus pectin agar for fungi) and CPAB (citrus pectin agar for bacteria). Cellulase and pectinase activity was specifically shown by clear zone around the cultures after flooding treatment with stain solution. Identification was conducted for isolate that showed the highest solubilizing index after screening section. Soil parameters that play role in microbial living in nature had been measured, such as pH, soil moisture content, bulk density, Ca, Mg, Fe, Cu, Mn, Zn, C-organic, total Nitrogen, and available Phosphate. In this research, 26 isolates of fungi and 29 isolates of bacteria were isolated. It was found that seven isolates of fungi and six isolates of bacteria showed positive result with clear zone around the cultures. The results of identification showed soil microbes with the highest cellulose and pectin solubilizing index are Bacillus brevis for bacteria and genus Helicoma for fungi.
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Judul: Eksplorasi Peran Mikrob dan Status Hara Tanaman terhadap Pembentukan Gaharu pada Aquilaria malaccensis
Abstrak: Agarwood is known as one of non-timber forest commodity in the world. Agarwood has a lot of function such as raw material for perfume, incense, cosmetics, and medicine for some diseases. Indonesia has a good potential resource to produce agarwoods. At present, mechanism and processes of agarwood formation is not yet known exactly. There are three hypothesis in agarwood formation, that are 1) pathology hypothesis, 2) sliced dan pathology, and 3) non-pathology hypothesis. Meanwhile, ancient community used traditional system to stimulate agarwood formation by slicing, nailing, branch cutting, and peeling of stem rind. This research was done to know microbial effect and plant nutrition status in Aquilaria malaccensis and their correlation in agarwood formation. Chemical and biological analysis were used in this research. Chemical analysis was used to determine plant nutrition status. Meanwhile biological analysis was used to examine the microbes that caused agarwood formation. The result of this reseach showed that agarwood was formed either because of assosiation between microbes and Aquilaria malaccensis and slicing in that plant. The highest microbial population was found in branch protected by canopy. According to physiologic analysis, not all microbes in agarwood can dissolve cellulose and pectin. A high number of Agarwood was formed in plant with high N and Mn contents. Field trial showed that fungi were more potential than bacteria in agarwood formation
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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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