Judul: Penapisan Bakteri Penghasil Senyawa Antimikrob Asal Spons Laut
Abstrak: Sponges are invertebrate found on coral reef ecosystems. Sponges produce many bioactive compounds as a result of secondary metabolites. The bioactive compounds is produced by microorganisms in the presence of sponges tissue as symbionts. Bioactive compounds are potential to be used in the biomedical and pharmaceutical fields, one of them is antimicrobial. This study aims to screen bacteria from marine sponges of Bira Island, Thousand Islands, DKI Jakarta Province, namely Callyspongia sp. and Petrosia sp. that could potentially produce antimicrobial compounds. The results of isolation using six types of medium showed a total of 147 bacterial isolates were isolated from the sponge type Callyspongia sp. and Petrosia sp. The suitable mediums used to isolate bacteria associated with sponge to obtain various types of bacterial colonies, were medium Nutrient Agar and Zobel Marine Agar. The results of the screening obtained from 26 isolates (13%) could produce antimicrobial compound. Seven isolates (5%) of them were able to inhibit five bacterial targets, i.e. Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Escherichia coli (ATCC 8739), and Enterophatogenic Escherichia coli (EPEC). The isolates were CAL36, CAL42, PTR8, PTR21, PTR40, PTR41 and PTR47. Gram staining performed on 26 bacterial isolates showed all of them belong to the group of gram-negative bacteria. Six isolates among 26 isolates were positive hemolysis derived from the sponge type Callyspongia sp., namely CAL22, CAL24, CAL25, CAL26, CAL34, and CAL49.
Keyword: Bogor Agricultural University (IPB), sponge Petrosia sp., sponge Callyspongia sp, hemolysis, Bira Island, antimicrobial compound

Judul: Penapisan bakteri penghasil senyawa antimikrob yang berasosiasi dengan spons Haliclona sp. dan deteksi gen penyandi poliketida sintase dan peptida sintase nonribosom
Abstrak: Sponges are classified in the Porifera phylum have the ability to symbiosis with microorganisms. The symbiont produced useful natural products such as polyketides and nonribosomal peptides that possessed antimicrobial activities. Each polyketide and non-ribosomal peptide are synthesized by the Polyketide Synthase (PKS) dan Non-Ribosomal Peptide Synthase (NRPS) gene. Both of them are multifunctional enzymes that involved in the biosynthesis bioactive compounds that are important in pharmaceutical and other industries.The aims of study was to screened the bacteria producing antimicrobial compounds which is associated with sponge and detect the genes that play a role in the biosynthesis of bioactive compounds. A total of 18 isolates bacteria that associated with Haliclona sp. was tested their antimicrobial activity and finally 12 isolates bacteria that inhibited four pathogenic bacteria growth that consist of Staphylococcus aureus, Enteropathogenic Escherichia coli (EPEC), Pseudomonas aeruginosa, Vibrio harveyi, and two non-pathogenic bacteria that consist of Bacillus subtilis, Escherichia coli, and the two pathogenic fungus Candida albicans and Candida tropicalis. Detection of PKS and NRPS encoding gene performed by Polymerase Chain Reaction (PCR) using specific primers, producing 700 bp and 1000 bp amplicon. One isolate that possessed the best antimicrobial activities and both of PKS and NRPS gene which is Iso 10 are selected for homology test. DNA fragment from Iso 10 KS genome (700 bp) that have been successfully cloned into plasmid pGEMT and sequenced and its homology with other KS domain sequences of about 49-51%.
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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