Judul: Kemampuan Bradyrhizohium Japonicum Menguraikan Beberapa Senyawa Aromatik
Abstrak: The aromatic compounds in soil can be used as carbon and energy sources for bacterial growth. BradyrhizobiulIl japolliculIl was able to degrade aromatic compounds because they have a B-ketoadipic route. This research was conducted to study the ability of B. japoniculIl (Bj) sirains in degrading some aromatic compounds. In the qualitative test, Bj strains were grown on synthetic agar media supplemented by 1 roM aromatic compound. Translucent halo around the colony was observed and measured on day-4. A quantitative test were performed by growing Bj strains on synthetic liquid culture supplemented by ] mM aromatic compound and 4.8 mM sodium glutamate. Optical density (00) was measured at )" 608 nm on every other days for 16 days, and pH fluctuation was observed at day-8 and day-16. To get aromatic compound residual, cultures were acidified to pH 1.0 at day-8 and day-I 6, and subsequently extracted. The extract was measured by visible-ultraviolet spectrophotometer at )" 249 nm (for parahydroxybenzoic acid) and at )" 253 (for protocathecuic and gentisic acids). The ability to degrade aromatic compounds qualitatively were showed by strains II, 38, 50, 33, 49, and 09 respectively. Gentisic acid was the compound that showed translucent halo for Bj II (10.5 mm), followed by parahydroxybenzoic acid for Bj 38 (3.5 mm), protocathecuic acid for Bj 33 (2.8 111m), and vanillic acid for Bj II and 33 (2 mm). The highest 00 during day-4 was obtained by strain 49 (protocathecuic acid) and strain 33 (parahydroxybenzoic acid). The highest pH final was showed by strain 33 (8.78) for protocathecuic, strain 38 (8.34) for parahydroxybenzoic, and strain 38 (8.76) for gentisic. The lowest aromatic compound residue was shown by strain 33 (0.016) for protocathecuic, strain 38 (0.066) for parahydroxybenzoic, strains 33 and 49 (0.056 and 0.051 respectively) for gentisic. According to the growth, pH media, and aromatic compound residual, the strains that show a better performance are strains 33 and 49 for protocathecuic, strains 33 and 38 for parahydroxybenzoic, strains 38 and 49 for gentisic acid.
Keyword: 

Judul: Media Optimal untuk Bradyrhizobium japonicum Toleran Asam- Aluminium Memproduksi Asam Indol Asetat bagi Pertumbuhan Kedelai
Abstrak: The demand on soybean recently increase either in quantity or in quality. However, Indonesia have not been soybean self-supporting yet, since low production of soybean especially on acid land. Nitrogen and micro-elements are very low, and aluminium (Al) toxicity become problem in acid land, as well as Bradyrhizobium japonicum (Bj) could not survived. Some of B. japonicum strains are able to syntheses Indole Acetic Acid (IAA) with tryptophan precursor and soybean symbiosis. The objectives of this research were: (1) to find optimal media for IAA production by tolerance acid-Al B. japonicum on the various tryptophan concentrate, and (2) to see the distribution of B. japonicum inoculant and their effects on soybean cultivar Tanggamus growth. Bradyrhizobium japonicum and tryptophan concentrations used in this experiment were Bj 11(wt), Bj 11(19), KDR 15(wt), and USDA 110, and 0.75 mM; 1.00 mM; 1.25 mM; 1.50 mM. For second experiment combination of B. japonicum and tryptophan concentrations, Bj 11 (wt) 1.00 mM tryptophan, Bj 11 (19) 1.50 mM tryptophan, KDR 15 (wt), 1.50 mM tryptophan, USDA 110 1.25 mM tryptophan from first experiment, and without Bj but plus 1.00 mM tryptophan utilized on Tanggamus of soybean at growth–pouch pH 4.5 using randomized completely design, in six replication. Bradyrhizobium japonicum Bj 11(wt) 1.00 mM and Bj 11(19) 1.5 mM tryptophan gave primary root and lateral root length of soybean longer, number of lateral root, and IAA content of soybean increase better than standar strain USDA 110.
Keyword: 

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