Judul: Penapisan dan Identifikasi Bakteri Rhizosfer Padi Penghasil Asam Indol Asetat pada Kondisi Salin
Abstrak: Increased salinity in farmland due to the rising sea level have an impact on ion balance, an increased of ethylene in roots, caused of hypo-osmotic condition in roots, and finally hinder the growth of root. Utilization of indigen rhizobacteria with ability to produce growth phytohormone indole-3-acetic acid (IAA) could become one of solution of this problem. This research aims to screening a number of rhizobacteria which have ability of producig phytohormone IAA and tolerant of salinity stress. A total of 48 rhizobacteria isolates from coastal rice field of Patimban and Eretan, west Java have been analyzed. Isolates Er B1.3 and Er B1.7a have ability to grow on minimal salt medium content with 15 % NaCl. Both isolates are still capable of producing IAA with consecutive concentrations at 11 ppm and 3.1 ppm on minimal medium salt content with 10 % NaCl. IaaM gene identification results prove that isolates Er B1.3 and Er B1.7a producing IAA through the IAM pathway. Based on the result of sequencing 16S Rrna gene known that isolate Er B1.3 and Er B1.7a belong to genus Brevibacterium and Aeromonas, respectively.
Keyword: Bogor Agricultural University (IPB), salinity stress tolerance, IAA production, rhizobacteria

Judul: Penapisan Deteksi PCR ACC Deaminase dan Analisis Produksi Auksin Rhizosfer Tanaman Padi Daerah Pesisir
Abstrak: Salinity and drought stress results in the production of ethylene. Rhizosphere bacterial activity suppresses the production of ethylene through the activity of 1-aminocycopropane-1-carboxylate (ACC) deaminase. In this study, a sampel of rhizosphere bacteria from coastal rice plant area was tested. The method used was acc deaminase activity test performed on Dworkin - Foster (DF) media and PCR acdS gene using specific primers of ACC and a quantitative analysis of the production of auxin (IAA). Of 47 isolates obtained, 8 were positively have acdS activity. The positive result was indicated by the presence of 1080 bp amplicon. Quantitative analysis showed the highest yield of 10.6 ppm of auxin. The results prove that there are some bacteria originated from coastal rice plant area which have acc deaminase activity.
Keyword: Bogor Agricultural University (IPB), rice, rhizosfere bacteria, salinity, drought, auxin, ACC deaminase

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