Judul: Uji Toksisitas Senyawa Bioaktif dari Bakteri yang Berasosiasi dengan Spons
Abstrak: Marine bacteria associated with sponges have been known as a source of bioactive compounds. Toxicity test of this compounds was done as initial test to determine the potency of bioactive compounds in pharmaceuticals development. The aim of this study was to extract and fractionate bioactive compounds from marine bacteria associated with sponges and to test its toxicity toward Artemia salina. Bacterial isolate of SAB E-31, SAB E-41, SAB E-57, HAL-13, HAL-74, and HAA-01 isolated from sponge were used as source of bioactive compounds. The bioactive compounds were extracted by using ethyl acetate. The ethyl acetate extract of SAB E-31, SAB E-41, SAB E-57, HAL-13, and HAA-01 were active with the lowest LC50 was 251.18 μg mL-1 from ethyl acetate extract of SAB E-41. The three of best ethyl acetate extract, SAB E-31, SAB E-41, and SAB E-57 were fractionated by preparative thin layer chromatography (PTLC) using eluent of nbutanol: ethyl acetate (3:7). Fractionation results of the three best ethyl acetate extract obtained 19 fractions, and 9 fraction among them were active fraction with the lowest LC50 from the fraction was 46.74 μg mL-1 come from SAB E-57.
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Judul: Toksisitas Ekstrak Senyawa Bioaktif dari Bakteri yang Berasosiasi dengan Spons dan Analisis DNA yang Berperan dalam Biosintesisnya
Abstrak: Sponges are organisms that produced many bioactive compounds and live symbiotically with many microorganisms. Symbiont microorganisms act as producers of bioactive compounds for sponge self-defense. This study aims to test the toxicity of the ethyl acetate extract sponge-associated bacteria against Artemia salina larvae and diversity analysis of DNA that play a role in the synthesis of bioactive compounds. BSLT was used as toxicity assay method and obtained LC50 values ranged from 117.1 μg/mL to 620 μg/mL. Fractionation of the ethyl acetate extract for isolates SAB E-35, SAB E-38 and SAB E-40 using preparative thin layer chromatography technique (PTLC) yielded fraction with the best LC50 value 116.7 μg/mL. Fraction 38-E of isolate SAB E-38 showed increase in LC50 value from its etyl acetat extract 138.6 μg/mL to 116.7 μg/mL. Isolates SAB E-35, SAB E-38, and SAB E-40 has gene that encoded the KS domain of PKS and A domain of NRPS with homology percentage from 47% to 100%. SAB E-40 has low homology and expected as potential producer of new bioactive compounds
Keyword: toxicity, sponge-associated bacteria, PKS, NRPS

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