Judul: Laju Potensial Nitrifikasi, Denitrifikasi, DNRA (Dissimilative Nitrat Reduction to Ammonium), dan Kelimpahan Bakteri di Lahan Perkebunan Sawit Jambi
Abstrak: Conversion of rainforest into plantations and agriculture lead to change microbial communities and nutrient cycle balance. One of nutrient cycle is Nitrogen Cycle. Several nitrogen metabolism that plays in nitrogen cycle are nitrification, denitrification, and DNRA (Dissimilative Reduction to Ammonium Nitrate). This research was conducted to calculate the potential rate of nitrification, denitrification, DNRA, and abundance of microbes possessing metabolism in oil palm plantation at Jambi. A total of 10 soil sample cores which 15 cm in depth was collected at 5 location in Palm Oil Plantation in Jambi. Ammonium, nitrite, and nitrate test have been undertaken used to determine the potential rate, Vmax, and Km. MPN (Most Probable Number) used to determine the abundance of bacteria. The results showed that DNRA rate was the highest rate and followed by denitrification and nitrification rate. DNRA bacteria abundance was noted at the bottom of stratification, while nitrification was noted at the upper of stratification. Denitrification rate showed no significant difference in the two stratifications were tested.
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Judul: Laju Potensial dan Kelimpahan Bakteri Nitrifikasi, Denitrifikasi dan Disimilatory Nitrate Reduction to Ammonium (DNRA) pada Lahan Perkebunan Karet di Jambi.
Abstrak: Nitrogen is an abundant element in nature. This element is an essential nutrient for plant growth. High demands of nitrogen because nitrogen is an integral component of many constituent compounds such chlorophyll, protein, enzymes, nucleic acids and nucleotides. Nitrogen cycle occur in nature in aerobic and anaerobic conditions. Nitrification is oxidation of ammonium to nitrate. Denitrification and disimilatory nitrate reduction to ammonium (DNRA) is the process of anaerobic nitrate reduction. This study aims to measure the potential rate of nitrification, denitrification, and DNRA and measure the abundance of bacteria in the rubber plantations in Jambi. Generally, denitrification activity was the most dominant activity. The lowest potential rate was DNRA. The high rate of denitrification was inversly proportional to the rate of DNRA because the availability of carbon source.
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Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology