Judul: Aktivitas fiksasi nitrogen dan oksidasi metan kultur campuran bakteri metanotrof pada lumpur sawah
Abstrak: Metanotroph bacteria are methane oxidizing bacteria. Besides, type II and type X of methanotrophic bacteria were also able to fix nitrogen using nitrogenase enzyme. This reasearch was conducted to test the activity of nitrogen fixation and methane oxidation of five isolates of methanotropic bacteria i.e. BGM 1, BGM 3, BGM 5, BGM 9, and SKM 14 which combined with one another. Seven combinations (SKM 14/BGM 1; SKM 14/BGM 3; SKM 14/BGM 5; SKM 14/BGM 9; BGM 9/BGM 1; BGM 9/BGM 3; BGM 9/BGM 5) were cultured and inoculated into NMS medium mixed with slurry of mud, then the activity of methane oxidation, nitrogen fixation and nitrogenase enzyme activity was tested. The highest accumulation of ammonium in the mud sterile treatment (35.489 μM) was higher than that of in non-sterile mud treatment (26.617 μM). Formulation 6 (BGM 9/BGM 3) in sterile mud treatment and formulation 4 (SKM 14/BGM 9) in non-sterile mud treatment has the highest nitrogenase enzyme activity, it was 5,16 mmol/h/ml culture and 75,85 mmol/h/ml culture respectively. Formulation 1 (SKM 14/BGM 1) and formulation 2 (SKM 14/BGM3) had the higest activity of methane oxidation in sterile and non sterile mud treatment i.e. 17428 and 16759 ppm /ml culture /day respectively.
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Judul: Efektivitas fiksasi N2 dan oksidasi metan kultur campuran bakteri metanotrof asal sawah
Abstrak: CH4 emissions in a rice field and wetlands is mostly produced by methanogenic bacteria and 80% of the CH4 is oxidized by methanotrophs. Besides of their ability to oxidize methane, methanotrophs also have ability to fix nitrogen. Four selected isolates of methanotrophs which had high nitrogen fixation activity i.e.(BGM 1, BGM 3, BGM 5, and BGM 9 isolates were combined with SKM 14 isolate which had high methane oxidation activity to obtain ideal formulations of the methanotrophs that have high activity of nitrogen fixation and methane oxidation activities. Nitrogen fixation activity was determined by measuring accumulated ammonium in medium and acetylene reduction assay (ARA). The highest concentraion of ammonium on single culture of methanotrophic bacterium was performed BGM 1 isolate (1,86 μM ammonium), and mixed culture of BGM3 and BGM9 isolates had the highest ammonium accumulation (4,905 μM ammonium). The highest nitrogenase activity was performed by mixed culture of BGM1 and SKM14 isolates, it was 11,27 μmol/ml cultures/hour. Whereas the higest methane oxidation was performed by mixed culture of BGM5 and BGM9 isolates, it was 18,20 ppm /ml cultures /day.
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Judul: Analisis Faktor-faktor yang Memengaruhi Permintaan Perhiasan Indonesia di Negara Tujuan Ekspor
Abstrak: Perhiasan merupakan salah satu produk potensial ekspor Indonesia. Secara umum, ekspor perhiasan ke negara tujuan menunjukkan kecenderungan berfluktuasi. Oleh karena itu, perlu dilakukan penelitian mengenai seberapa besar pengaruh faktor luar seperti GDP per kapita negara tujuan, harga ekspor perhiasan Indonesia, harga ekspor perhiasan negara pesaing, populasi negara tujuan, dan nilai tukar riil rupiah terhadap permintaan ekspor perhiasan Indonesia. Penelitian ini menggunakan data panel, yang merupakan gabungan data time series rentang waktu 2000-2011 dan data cross section yaitu tujuh negara tujuan ekspor utama. Data dianalisis menggunakan model Fixed Effect. Hasil penelitian menunjukkan bahwa (1) nilai ekspor perhiasan Indonesia menunjukkan tren yang positif, namun volume ekspor perhiasan Indonesia menunjukkan adanya fluktuasi; (2) faktorfaktor yang memengaruhi permintaan ekspor perhiasan Indonesia yaitu GDP per kapita negara tujuan, harga ekspor perhiasan Indonesia, populasi negara tujuan, dan nilai tukar riil rupiah.
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