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: 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: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular