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Abstrak :
Klebsiella sp. GMD08 is one of the bacteria that has the capability to dissolve insoluble inorganic phosphate into soluble phosphate ion through their organic acid production. Transposon is a genetic element agent usually used to generate mutant through mutagenesis. Thus it can be used to identify the genetic functions involved in those phosphate solubilizing mechanisms. This research was conducted to identify the genes of Klebsiella sp. GMD08 involved in phosphate solubilization through sequence detection obtained from a hyper-solubilizing phosphate mutant library. Mutation was conducted by inserting mini-Tn5 transposon hosted in Escherichia coli S17-1/λpir [pBSL202] into Klebsiella sp. GMD08 chromosome by the filter mating conjugation method. Trans conjugant mutant candidates were then qualitatively and quantitatively analyzed for their solubilizing ability to dissolve tricalcium phosphate [Ca3(PO4)2] using pikovskaya medium. The organic acid characteristics of transconjugant mutants were detected using High-performance liquid chromatography (HPLC). Meanwhile, suspected genes involved in phosphate solubilizing were detected using the sequencing method obtained from the transposon insertion result. Nucleotide Basic Local Alignment Search Tool (nucleotide BLAST) was used to identify the nucleotide base sequence similarity with the database. The results showed that PB116 and PB122 were the two main transconjugant mutants obtained from transposon mutagenesis which had higher tricalcium phosphate dissolving ability. Gluconic acid was the main organic acid produced by Klebsiella sp. GMD08 phosphate solubilizing mechanism. Moreover, arginine repressor (ArgR) and malate dehydrogenase gene (mdh) coding gene were involved in Klebsiella sp. GMD08 phosphate solubilizing mechanism.

Abstrak :
ABSTRAK
Xanthomonas oryzaepv. oryzae (Xoo) menyebabkan hawar daun bakteri (HDB) pada padi (Oryza sativaL.), yang merupakan penyakit utama dan menjadi pembatas bagi produksi tanaman pokok di banyak negara di dunia. IsolasiXoo dilakukan dari daun padi yang terserang hawar daun bakteri. Identifikasi X. oryzae pv. oryzae dilakukan berdasarkan pada gejala yang ditimbulkannya, patogenisitas, karakter morfologi, fisiologi, dan genetik biakan bakteri yang diisolasi dari tanaman padi yang terinfeksi Xoo. Sebanyak 50 isolat yang diduga Xoo telah berhasil diisolasi. Bakteri tersebut bersifat aerobik, berbentuk batang, dan tergolong Gram negatif. Isolat-isolat tersebut diuji hipersensitivitasnya pada tanaman tembakau dan patogenisitasnya pada padi. Kelima puluh isolat bakteri tersebut mampu menginduksi reaksi hipersensitif pada tanaman tembakau dan menyebabkan gejala sakit pada tanaman padi dengan perkembangan gejala yang berbeda. Hasil uji fisiologi, reaksi hipersensitivitas dan patogenisitas, tiga isolat bakteri yang diduga kuat Xoo yaitu STG21, STG42, dan STG46 menunjukkan bahwa bakteri tersebut tidak membentuk indol, tidak menghasilkan pigmen flouresens, menghidrolisis kasein, memiliki aktivitas enzim katalase, tetapi tidak memiliki aktivitas enzim oksidase. Hasil parsial sekuensing gen penyandi 16S rRNA dari STG21 dan STG42 menunjukkan homologi dengan X. oryzae pv oryzae masing-masing sebesar 80% dan 82%, sedangkan STG46 menunjukkan homologi dengan X. campestris sebesar 84%. Mutagenesis dengan transposon Mini-Tn5 pada STG21 menghasilkan salah mutan (M5) yang tidak dapat menginduksi reaksi hipersensitif pada tanaman tembakau dan berkurang patogenisitasnya pada padi. Panjang gejala HDB pada padi yang ditimbulkan mutan M5 berkurang sebesar 80%.

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Abstract
X. oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) of rice ( Oryza sativa L.), a major disease that constrains production of the staple crop in many countries of the world. Identification of X. oryzae pv. oryzae (Xoo) was conducted based on the disease symptoms, pathogenicity, morphological, physiological, and genetic characteristics of bacterial cultures isolated from the in fected plants. Fifty bacterial isolates predicted as Xoo have been successfully isolated. They are aerobic, rod shaped, and Gram negative bacteria. The isolates were evaluated for their hypersensitivity in tobacco and pathogenicity in rice plant. Fifty isolates induced hypersensitive reaction in tobacco and showed pathogenicity symptom in rice in different length. Based on physiological test, hypersensitivity and pathogenicity reactions, three bacterial isolates strongly predicted as Xoo, i.e. STG21, STG42, and STG46, were non indole formation, non pigment fluorescent, hydrolyzed casein, catalase activity positive, but negative oxidase. Partial sequencing of 16S rRNA genes of STG21 and STG42 showed 80% and 82% homology with X. oryzae, respectively, while STG46 showed 84% homology withX. campestris. Mini-Tn5 transposon mutagenesis of STG21 generated one of the mutants (M5) lossed it?s ability to induce hypersensitive reaction in tobacco plant and deficient in pathogenicity on rice. The lesion length of rice leaf caused by the mutant M5 decreased up to 80%.