Judul: Marka Molekuler untuk Mendeteksi Xanthomonas oryzae pv. oryzae Asal Jawa Barat dan Karakterisasi Patogenik Secara In Vivo
Abstrak: ra In Vivo. Dibimbing oleh SURYANI dan A. ZAENAL MUSTOPA Hawar daun bakteri (HDB) adalah penyakit serius pada padi yang dapat mengurangi hasil panen. Penyakit ini disebabkan oleh bakteri Xanthomonas oryzae pv oryzae (Xoo). Upaya yang telah dilakukan untuk mengendalikan HDB diantaranya penggunaan antibiotik, kombinasi pupuk, sanitasi, kombinasi antagonis Pantoea agglomerans, Pseudomonas fluorescens, dan Bacillus subtilis dan penggunaan varietas tahan HDB. Meledaknya kasus HDB di Indonesia khususnya Jawa Barat, maka perlu dilakukan peninjauan dan evaluasi kembali penyakit ini agar dapat dilakukan penanganan yang tepat. Penelitian ini bertujuan mendeteksi Xoo asal Jawa Barat dengan menggunakan marka molekuler dan mengetahui tingkat virulensinya dengan karakterisasi patogenik secara in vivo. Tahapan penelitian yang dilakukan adalah isolasi bakteri Xoo berdasarkan morfologinya, deteksi bakteri dengan marka molekuler, dan karakterisasi patogenik bakteri Xoo secara in vivo dengan varietas padi yang tahan HDB (IRBB7 dan Conde) dan varietas rentan HDB (IR64 dan TN 1). Hasil identifikasi 240 isolat bakteri penyebab infeksi tanaman padi dari 50 lokasi di Jawa Barat dengan tiga pasang primer spesifik (XO1, Xoo4009, dan Xoo2976) menunjukkan hanya empat isolat yang positif Xoo, yaitu isolat 6D (Cicalengka-Bandung), 17D (Sindang Karya-Karawang), 19D (Rawamerta-Karawang), dan 21D (Teluk Jambe-Karawang). Isolat 6D digunakan untuk analisis lebih lanjut yaitu tahap sequencing yang menunjukkan kemiripan 98 % pada forward dan 96 % pada reverse dengan Xoo PX099A strain Filipina, Xoo MAFF311018 strain Jepang, dan Xoo KACC10331 strain Korea. Karakter patogenitas secara in vivo menunjukkan tingkat kerusakan tertinggi terjadi pada varietas padi TN 1. Varietas IRBB7 dan Conde telah memasuki status agak rentan HDB. Tingkat virulensi tertinggi terjadi pada isolat 6D dan terendah terjadi pada isolat 21D. Intensitas penyakit HDB pada tanaman fase bibit lebih tinggi dibanding dengan fase dewasa.
Keyword: Bacterial Leaf Blight (BLB), morphologic Xoo bacterial isolation, bacterial pathogenicity, Cicalengka-Bandung, Rawamerta-Karawang, Teluk Jambe Karawang

Judul: Penapisan Bakteri Filosfer Penghasil Senyawa Bioaktif Anti Xanthomonas oryzae pv. oryzae Penyebab Penyakit Hawar Daun Bakteri pada Padi
Abstrak: Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the important diseases in rice crops. The disease is difficult to control because it attacks the rice plant at different growth stages ranging tillering, flowering and ripening. One alternative that can be used to control the spread of BLB is using the biocontrol agent which can be obtained from phyllosphere. This study aims to isolate, characterize and screen the rice phyllosphere bacteria producing bioactive compounds anti Xoo causes BLB in rice. Phyllosphere bacteria isolated from rice leaves Ciherang healthy age of 2.5 months using 4 different media obtained 285 bacterial isolates, the 65 isolates of King’s B agar, 86 isolates of nutrient agar, 81 isolates of Luria-Bertani agar, and 53 isolates of trypticase soy agar. Antagonist test using double layer method showed 58 isolates phyllosphere bacteria potential as a biocontrol agent producing bioactive compounds Xoo. Pathogenicity test showed 18 isolates not potentially pathogenic to rice plants. Among the 18 non-phytopathogenic isolates, 14 isolates including Gram-positive bacteria, 4 isolates Gram-negative bacteria, and 5 isolates of Bacillus suspected. Three of the 18 isolates (BFSGb 8, BFSGb 55, and BFSGb 99) has the largest index value inhibition of in-vitro against Xoo is 1.33, 1.67, and 1.33 respectively to isolate BFSGb 8, BFSGb 55, and BFSGb 99.
Keyword: Bogor Agricultural University (IPB), Xanthomonas oryzae pv. oryzae., phyllosphere bacteria, bioactive compounds, Bacterial leaf blight

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.
Keyword: