Judul: Isolasi dan Karakterisasi Bakteri Penghasil Indole-3-Acetic Acid (IAA) yang Berasal dari Area Penambangan Batu Kapur.
Abstrak: Soil degradation due to limestone activity can be overcome by planty plant reclamation. The growth of seedling plants reclamation can be induced to grow well on nutrient-poor and alkaline soil condition by using the indigenous bacteria, such as IAA producing bacteria. The research was aimed to isolate and characterize Indole-3-acetic acid (IAA) producing bacteria from limestone quarry. Isolation was performed on 13 soil samples of limestone quarry, and then 25 isolates were obtained. The selection by hypersensitive test showed 2 isolates used to test further, namely isolate QC 5C32 and QC 7B41. Both isolates were identified by KIT API 50 CH, a series of biochemistry reaction had 99.9% similarity with Bacillus megaterium, had rod-shapes, Gram positive, and produced endospore. The highest IAA production occured by adding 1.5 mM of Ltryptophan. The result showed that amount of IAA was 10.345 ppm (QC 5C32) and 18.723 ppm (QC 7B41). Application of both isolates toward siratro (Macroptilium atropurpureum) showed impact to the growth of primary root, number of lateral root, and fresh weight of siratro root sprout.
Keyword: Bacillus megaterium, Plant growth promoting rhizobacteria (PGPR), reclamation

Judul: Pengujian Potensi Bakteri Penghasil Indole-3-Acetic Acid (Iaa) Asal Tanah Batuan Kapur Pada Penanaman Lamtoro (Leucaena Leucocephala)
Abstrak: Tanah bekas tambang batuan kapur merupakan tanah yang kering dengan diversitas mikrob yang rendah sehingga diperlukan usaha untuk mengembalikan keadaan tanah menjadi produktif kembali. Reklamasi dapat dilakukan dengan menambahkan pupuk, melakukan penanaman kembali, serta menginduksi bakteri tanah yang bermanfaat. Bakteri yang bermanfaat salah satunya ialah bakteri yang mampu menghasilkan zat pemacu pertumbuhan (ZPT). Penanaman kembali dapat dilakukan dengan beberapa jenis tanaman legum, misalnya lamtoro. Tanaman lamtoro (Leucaena leucocephala) merupakan tanaman leguminosa yang paling produktif dibandingkan yang lain, kualitas hijaunya tinggi, tahan kekeringan, dan tumbuh dalam variasi iklim yang luas. Penelitian ini bertujuan untuk mengetahui potensi bakteri penghasil Indole-3-Acetic Acid (IAA) terhadap pembibitan lamtoro. Isolat yang terpilih diketahui menghasilkan IAA setelah dilakukan uji kolorimetri dengan reagen Salkwoski. Hasil uji hipersensitivitas dengan menggunakan daun tembakau diperoleh dua isolat yang bersifat nonpatogen yang akan diujikan potensinya pada tanaman lamtoro. Isolat QC 7B41 menghasilkan IAA tertingi pada jam ke-30 dan isolat QC 5C32 pada jam ke-27. Pemberian bakteri berpengaruh positif terhadap pertumbuhan akar primer dan jumlah akar lateral pada tanaman bibit lamtoro hingga 83 hari setelah tanam.
Keyword: batu kapur, IAA (Indole-3-Acetic Acid), lamtoro, mikrob

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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