Judul: Potensi Bacillus sp. Galur G3, Bacillus firmus E65, dan bakteri metanotrof sebagai penghambat pertumbuhan patogen Xanthomonas oryzae pv. oryzae dan Rhizoctonia solani
Abstrak: The use of bacilli and methanotropic bacteria as biocontrol agents for rice bacterial pathogens of X. oryzae pv. oryzae and R. solani can enhance rice production and reduce methane emission from rice fields. Some of methanotrophs had nitrogen fixation activity. Antagonism methods was tested to determine the ability of two bacilli species (Bacillus sp. G3 and B. firmus E65) and two methanotrophs (BGM 9 and SKM 14) in inhibiting growth of X. oryzae pv. oryzae and R. solani and inhibition between the two groups of bacteria. Methanotrophs (BGM 9 and SKM 14) inhibited growth of X. oryzae pv. oryzae with inhibition index (IP) of 2,27 and 2,79 respectively. Bacillus sp. G3, B. firmus E65 and SKM 14 isolates inhibited growth of R. solani with inhibition index of 0.63, 0.64, and 0.56 respectively. B. firmus E65 inhibited growth of methanotrophs (BGM 9 and SKM 14) and R. solani. Formulation of biocontrol agents containing Bacillus sp. G3 and methanotrophs (BGM 9 and SKM 14) can be done because there was no antagonism among the three bacteria. However the combination of B. firmus E65 and the metanotrophs should not be done in one formulation because of the antagonism between B. firmus E65 and the metanotrophs.
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Judul: Antimicrobial Activity of Bacillus sp. to Xanthomonas oryzae pv. oryzae, Pseudomonas syringae pv. glycines, and Pseudomonas fluorescens.
Abstrak: Leaf blight disease caused by bacterial plant pathogen such as X. oryzae pv. oryzae and P. syringae pv. glycines had deathly effect to plants. The pathogens can be controlled by biological control using P. fluorescens or antimicrobial substances. The research studied the inhibition ability and production of antimicrobial substances produced by Bacillus sp. againts bacterial plant pathogen such as X. oryzae pv. oryzae, P. syringae pv. glycines, and biological control P. fluorescens. As many as 31 Bacillus sp. isolates isolated from forest soil was determined their antimicrobial activity against indicator bacteria using double layer method. The result showed that 13 isolates was able to inhibit Staphylococcus aureus, Eschericia coli, and X. oryzae pv. oryzae growth, 8 isolates could inhibit P. fluorescens A growth, 9 isolates could inhibit P. fluorescens B growth, and 8 isolates could inhibit P. syringae pv. glycines growth. Bacillus sp. F13 had the fastest inhibition and good efficiency against all indicator bacteria. Mixed culture competition test showed that this isolate had a broad spectrum inhibition activity, it was able to inhibit Gram positive and Gram negative bacteria. The isolate could inhibit growth of P. syringae pv. glycines and X. oryzae pv. oryzae up to 100%. The antimicrobial substance the isolate was produced in the late logarithmic growth phase.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh.
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. ,,,
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular.