Judul: Potensi Beberapa Bakteri Penghambat Pertumbuhan Xanthomonas oryzae pv. oryzae Penyebab Penyakit Hawar Daun Bakteri pada Tanaman Padi
Abstrak: Bacterial leaf blight (BLB) disease caused by plant pathogenic bacteria Xanthomonas oryzae pv. oryzae (Xoo) could lead to death of rice plants. Control of plant pathogenic bacteria can be performed using biological control agents. The aim of this research was to study the inhibitory ability of eight isolates of biocontrol bacteria against Xanthomonas oryzae pv. oryzae (Xoo) under greenhouse conditions. Isolates of biological agents used in the study were obtained from IPB Culture Collection (IPBCC), Department of Biology, IPB and microbial gene bank collection of Indonesian Center for Agriculture Biotechnology and Genetic Resources (BB Biogen), consisting of Pseudomonas aeruginosa C32a and C32b, P. fluorescens ATCC 13525 Pf , Serratia marcescens E31, Bacillus sp. I.5, B. cereus I.21 and II.14, and B. firmus E65 isolates. The methods used in the research i.e. hypersensitivity test, antagonistic test of biocontrol bacteria to Xoo, and in vivo application of biological agents in the greenhouse condition. Hypersensitivity test on tobacco plants using C32a and C32b inoculums showed characteristics of slightly leaf yellowing but did not cause necrosis. Injection using Xoo inoculum showed necrosis on tobacco leaves. Antagonist isolates i.e. C32a, C32b, Pf, I.21, and I.5 showed inhibitory activity against Xoo, whereas others isolates did not show inhibitory activity. In greenhouse experiments IR 64 rice plants were sprayed with biological control agents (107cfu/ml) at 7 days, 14 days, 28 days, and 42 days after planting. The results showed that C32a isolate could suppress better the lesion length of BLB than that of chemical control (copper sulphate). Growth measurement of rice plants were assessed on plant height, number of tillers, panicle number and grain weight. Rice plants spraying treatment with isolates E65, E31, C32a, C32b, I.21, Pf, and I.5 showed no difference with control of sterile distilled water. Spraying with each suspension isolate of I.21, E31, C32a, Pf, and C32b indicated no different in the panicle number, in addition rice production was higher in C32a, Pf, C32b, and I.21 treatments. Spraying with C32a isolates produced the highest grain production compared with that of other isolates.
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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: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf