Judul: Purification, Characterization and Antibiotic Activity of Metabolite Soil Actinomycetes East Kalimantan Origin
Abstrak: Infectious diseases such as tuberculosis (TB), diarrhea and pneumonia are the leading causes of death other than stroke, hypertension and cancer. Infectious disease is a disease caused by pathogenic microbes. Drugs are often used to overcome this disease is antibiotics. With the development of resistant microbial pathogens and the emergence of new infectious diseases, it is important to search for new anti-infective drugs as well. Currently, the source of microbes being developed because of their ability in producing a large variety of active compounds are microbes which are grouped in actinomycetes and mold, from 16,500 antibiotic isolated from microbes, 52,7% were from actinomycetes. The purpose of this study was to purify and characterize the antimicrobial compounds from metabolite soil actinomycetes from East Kalimantan. Butanol extract of fermentation cultures were fractionated by column chromatography. The resulting fractions are tested for antimicrobial activity. The most active fraction was purified by Thin Layer Chromatography (TLC) and preparative High Performance Liquid Chromatography (HPLC), meanwhile the compound purity was analyzed using the HPLC. The result of purified compound was then characterized using Fourier Transform Infra Red (FTIR) and Liquid Chromatography Mass Spectrophotometer (LCMS). Fractionation step using column chromatography resulted in 8 fractions (fractions F1 - F8) which were then tested for their activity. Only a fraction F5 - F8 which provides microbial activity against Bacillus subtilis, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Fraction F8 produced the largest diameter of the clear zone of the bacterial test. Purification result of fraction F8 using preparative HPLC produced 8 fractions, fraction F8.1 - F8.8. Activity test of all the fractions (F8.1 – F8.8) showed that F8.5 had the largest diameter of clear zone against B. subtilis and S. aureus compared to others fractions, 14.44 mm and 10.41 respectively. F8.5 fraction analysed by FTIR showed that the compound has a carbonyl functional group (C=O) of a carboxylic acid, OH group, C–O alcohols group, aliphatic CH groups, aromatic C=C group and C≡N nitrile group. LC-MS analysis of the F8.5 fraction showed that the compound has a molecular weight of 403 Da with an approximate molecular formula C10H23N6O6.
Keyword: soil actinomycetes, antibiotic, Streptomyces, purification

Judul: Isolation, purification, identification, and fermentation medium optimization of antibiotic produced by marine actinomycetes
Abstrak: Kebutuhan antibiotik, anti fungal, maupun anti kanker baru masih sangat diperlukan, terutama yang efektif melawan bakteri resisten, virus, protozoa, fungi atau kanker. Untuk mendapatkan antibiotik baru, para peneliti telah banyak melakukan berbagai cara seperti eksplorasi senyawa aktif dari mikroba, tumbuhan, maupun sintesis secara kimia. Salah satu mikroba yang banyak diteliti untuk diambil senyawa aktifnya adalah aktinomisetes. Indonesia merupakan negara kepulauan yang memiliki bentangan laut yang luas, kurang lebih 3,1 juta km2 atau hampir 2 kali lipat dibandingkan luas daratannya. Karakteristik laut yang bermacam-macam mengindikasikan biodiversitas hayati yang besar, khususnya biodiversitas mikroba laut. Namun demikian potensi ini belum banyak dimanfaatkan. Penelitian ini bertujuan untuk mendapatkan senyawa aktif yang berpotensi sebagai antibiotik dan memproduksinya dalam skala laboratorium yang dihasilkan oleh aktinomisetes laut melalui isolasi, penapisan, pemurnian, identifikasi dan optimasi medium fermentasi.
Keyword: Streptomycetaceae, Fertil aerial micellium

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