Judul: The potency of endophytic bacteria as biocontrol agents to control blood disease on banana
Abstrak: Blood disease of banana caused by blood disease bacterium (BDB) is an important disease of bananas in Indonesia. The available control techniques have not been able to solve the disease problem effectively. Therefore, the development of more effective control method is needed. Endophytic bacteria have potencies as candidates of biological control agents to blood disease, because the bacteria as reported to be associated with plant resistance to pathogens and plant growth promotion. The aim of the studies were to (1) explore, select and identify endophytic bacteria to control blood disease on banana; (2) determine the mechanisms of endophytic bacteria to control blood disease on banana; (3) evaluate endophytic bacterial colonization on banana plant and their effect on the effectiveness to control blood disease; and (4) analyse the effect of application method of endophytic bacteria to their effectiveness to control blood disease on banana. Ninety isolates of endophytic bacteria have been isolated from the root of banana. The average population densities of the bacteria varied between 6.0 x 103 and 4.2 x 105 cfu/g fresh weight of root. Twenty seven among the ninety isolates positively produced inhibition zone toward blood disease bacterium (BDB). However, only four isolates (EAL15, EKK10, EKK20, EKK22) were able to reduce the incidence of blood disease on banana with ranged from 66.67% to 83.33%. Based on the partial sequence of 16S rRNA, four isolates were identified as Serratia liquefaciens (EAL15), Bacillus megaterium (EKK10), Enterobacter cloacae (EKK20) and Pectobacterium cypripedii (EKK22). The mechanisms of endophytic bacteria to control blood disease on banana were induced resistance, based on their activities in increasing peroxidase, polyphenol oxidase and salicylic acid content. The endophytic bacteria EAL15-Rif colonized within roots and stem tissues of young banana trees at four weeks after inoculation. Histological analysis using Scanning Electron Microscopy showed that EAL15-Rif colonise within the root and stem tissues of banana. The colonization period of endophytic bacteria during the eight months suppressed the blood disease incidence on banana ‘Cavendish’ with ranged from 66.67% to 83.33%. Application of endophytic bacterial community K-AL3 and K-RB1 were able to suppress the blood disease incidence on ‘Kepok kuning’ cultivar as much as 75.00% and 83.33%.
Keyword: Pseudomonas solanacearum, Ralstonia solanacearum, Endophytic bacteria, Blood disease bacterium, Induce resistance, Banana

Judul: Potensi Asap Cair dan Bakteri Endofit Penghasil AHL-Laktonase untuk Pengendalian Penyakit Darah pada Pisang.
Abstrak: Penyakit darah yang disebabkan oleh Blood Disease Bacterium (BDB) merupakan penyakit penting pada tanaman pisang. Beberapa teknik pengendalian seperti penggunaan bibit sehat, sanitasi, eradikasi, pembungkusan buah, dan pemotongan bunga jantan telah banyak dilakukan namun belum sepenuhnya efektif mengendalikan penyakit ini khususnya di Indonesia. Alternatif pengendalian BDB yang saat ini dikembangkan adalah aplikasi asap cair dan bakteri endofit penghasil AHL-laktonase. Penelitian ini bertujuan mendapatkan informasi keefektifan asap cair, bakteri endofit penghasil AHL-laktonase beserta kombinasinya dalam menghambat BDB secara in vitro dan menginduksi ketahanan bibit pisang. Daya hambat asap cair terhadap BDB dan bakteri endofit diuji menggunakan teknik peracunan media tumbuh untuk menentukan perlakuan kombinasi. Uji in vitro pengaruh asap cair dan bakteri endofit dalam menghambat pertumbuhan BDB dilakukan dengan modifikasi teknik peracunan media dan uji kompetisi kultur campuran. Uji pengaruh asap cair dan bakteri endofit dalam induksi ketahanan dilakukan dengan teknik injeksi pada bonggol pisang. Pengaruh induksi ketahanan ditentukan melalui analisis peningkatan total protein dan peningkatan aktivitas peroksidase jaringan daun pada hari ke-7 setelah perlakuan. Hasil penelitian menunjukkan bahwa perlakuan asap cair pada konsentrasi 0.3% merupakan konsentrasi hambatan minimum asap cair terhadap pertumbuhan BDB. Asap cair pada konsentrasi 0.3% tidak menghambat pertumbuhan isolat CBP1 dan DBT7 sehingga pada konsentrasi tersebut asap cair dapat dikombinasikan dengan CBP1 dan DBT7. Perlakuan asap cair 0.3% dapat menghambat pertumbuhan BDB pada media TZC dan meningkatkan protein total pada jaringan daun bibit pisang. Perlakuan asap cair 0.25% berpotensi menginduksi ketahanan karena dapat meningkatkan aktivitas peroksidase pada bibit pisang.
Keyword: Blood Diease Bacterium, induce systemic resistance, peroksidase

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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