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: Ekstraksi dan Bioaktivitas Senyawa Antimikrob dari Bakteri yang Berasosiasi dengan Spons Jaspis sp.
Abstrak: Many bacteria associated with sponges produced secondary metabolite or bioactive compounds that has been identified as antimicrobial, anti-cancer, anti-fungi, and anti-bacteria. This study aims to extract antimicrobial compound produced by bacteria associated with sponge Jaspis sp and to test its toxicity toward Artemia salina prawn. Six potential isolates of bacteria isolated from sponge Jaspis sp., coded as SAB E-8, SAB E-33, SAB E-35, SAB E-38, SAB E-40, and SAB S-43, were extracted by using ethyl acetate solvent. Bacterial crude extracts of antimicrobial compounds were tested its activity toward pathogenic and non-pathogenic microbes. The results revealed that the crude extracts of bacteria inhibited the growth of E. coli, B. subtilis, EPEC K1-1, Stapylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Candida tropicalis. The minimum inhibitory concentration (MIC) from bacterial supernatants range from 12.5% to 100%. Three best isolate i.e. SAB E-35, SAB E-38, and SAB S-43 were fractionated by using thin layer chromatography (TLC). Results of TLC under UV 365 nm and UV 254 nm showed that each extract had active fraction that inhibited P. aeruginsa and EPEC K1-1 through bioautography test. The six bacterial crude extracts were also tested using brine shrimp lethality test (BSLT) with Artemia salina as test organism to find out the toxicity concentration of the extract. Results showed that each extract had different toxicity measured with LC50 provision. SAB E-38 produced the lowest LC50 value which was 81 mg/L.
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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