Judul: N2 fixation and methane oxidation activity of mixed of culture of Azotobacter sp., Azospirillum sp., and Methanotrophic Bacteria
Abstrak: Metanotrophs bacteria are methane oxidizing bacteria. Methanotrophic bacteria especially type II and type X were also able to fix nitrogen using nitrogenase enzyme. This reasearch was conducted to determine activity of methane oxidation and nitrogen fixation of four isolates of methanotropic bacteria i.e. BGM 1, BGM 5, BGM 9, and SKM 14 which were combined with nitrogen-fixing bacteria (Azotobacter sp. and Azospirillum sp.). Six combinations were cultured and then inoculated into nitrogen free NMS medium. Activity of methane oxidation and nitrogen fixation activity was analysed. The highest methane oxidation activity was found in the mixed culture of BGM 9, BGM 5, Azotobacter sp., and Azospirillum sp. isolates. The activity was 184.5 x 10-8 ìM/cell /day. The highest accumulation of ammonium was found in the mixed culture of BGM 5, BGM 9, and Azotobacter sp. isolates. The concentration of accumulated ammonium was 4.075 ìM. Methane oxidation activity and ammonium accumulation of methanotrophic bacteria showed higher result when they were combined with nitrogen fixing bacteria.
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Judul: Seleksi dan Uji Aktivitas Fiksasi Nitrogen (N2) Bakteri Metanotrof Asal Sawah pada Konsentrasi Oksigen (O2) Berbeda.
Abstrak: Methanotrophic bacteria is methane oxydizing bacteria. This bacteria has a specific enzyme known as methane monooksigenase (MMO) catalizing reaction of CH4 and O2 to methanol. Methanotrophic bacteria also have ability to fix nitrogen. Methanotrophic bacteria type II and type X could fix nitrogen using nitrogenase enzyme. This enzyme is very sensitive to oxygen. As many as 19 isolates of methanotrophic bacteria was recultured and determined their nitrogen fixation activity at different oxygen concentration. Nitrogen fixation activity was determined by measuring ammonium accumulation in NMS free nitrogen medium. High ammonium accumulation was found at cultures of BGM 1, BGM 3, BGM 5, dan BGM 9 isolates. The highest ammonium accumulation (88,816 <M) was showed by BGM 9 isolate on 30% oxygen concentration and the highest cell density was showed by BGM 5 isolate (OD 0,103) on 80% oxygen concentration.
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Judul: Kerugian ekonomi akibat serangan rayap pada bangunan perumahan di dua wilayah DKI Jakarta (Kotamadya Jakarta Barat dan Jakarta Timur)
Abstrak: Perusakan bangunan rumah oleh rayap dipengaruhi oleh kondisi lingkungan tempat hidupnya. Peranannya bervariasi untuk masing-masing tempat. Daerah-daerah tertentu misalnya dekat sungai, banyak pepohonan, kelembaban, dan curah hujan yang cukup cenderung tinggi tingkat serangan rayapnya. Daerah Kecamatan Keramat Jati dan Ciracas merupakan daerah yang kerugian ekonominya cukup tinggi, yaitu sebesar Rp. 5.496.490 dan Rp. 4.193.353, disusul daerah Palmerah, Kembangan, Kebun Jeruk dengan kerugian sebesar Rp. 4.895.392, Rp. 4.735.653, dan Rp. 4.732.646. Kerugian yang terkecil terdapat pada daerah Kecamatan Cipayung yaitu sebesar Rp. 4.255.909. Penelitian juga mengungkapkan bahwa adanya hubungan antara umur bangunan rumah dengan tingkat serangan rayap dan besarnya kerugian ekonomi akibat serangan rayap. Tingkat serangan rayap dan kerugian ekonomi berbanding lurus dengan kelas umur bangunan rumah, semakin besar umur bangunan tingkat serangan rayap dan kerugian ekonomi akan semakin besar. Daerah Kecamatan Keramat Jati, Ciracas dan Palmerah perlu mendapat perhatian yang serius, mengingat daerah tersebut mempunyai kerugian ekonomi yang cukup tinggi akibat serangan rayap. Diharapkan para pengambil kebijaksanaan dalam merancang desain bangunan perumahan dapat memperhatikan proteksi bangunan terhadap bahaya rayap.
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