Judul: Characterization of Pigmented Actinobacteria through Several Polyphasic Taxonomic Approaches
Abstrak: Aktinobakteri berpotensi menghasilkan komponen metabolit sekunder salah satunya pigmen. Karakterisasi aktinobakteri berpigmen dapat dilakukan melalui pendekatan taksonomi polifasik. Aktinobakteri berpigmen yang dimiliki Laboratorium Mikrobiologi, Departemen Biologi FMIPA IPB diketahui dapat menghasilkan metabolit sekunder pigmen berkhasiat antioksidan. Namun, karakter dari isolat tersebut belum diketahui secara keseluruhan. Penelitian ini bertujuan mengkarakterisasi aktinobakteri berpigmen koleksi Laboratorium Mikrobiologi, Departemen Biologi FMIPA IPB melalui beberapa pendekatan taksonomi polifasik. Tahapan penelitian meliputi purifikasi, pertumbuhan dan karakterisasi morfologi koloni aktinobakteri pada berbagai media, kemampuan tumbuh pada berbagai sumber karbon, identifikasi gen 16S rRNA serta analisis bioinformatika. Lima isolat mampu tumbuh optimal pada media ISP 2. Morfologi koloni kelima isolat berbeda pada setiap media. Empat isolat termasuk genus Streptomyces, sedangkan satu isolat lainnya termasuk rare-actinobacteria non Streptomyces. Setiap isolat memiliki kemampuan tumbuh pada sumber karbon yang berbeda-beda. Hasil identifikasi molekuler gen 16S rRNA isolat HVB menunjukkan ukuran amplikon ~1465 pb yang memiliki kemiripan sebesar 91.62% dengan spesies Rhodococcus wratislaviensis strain G119. Kata kunci: aktinobakteri, molekuler, pigmen, rare-actinobacteria, taksonomi polifasik, Actinobacteria have the potential to produce secondary metabolite components such as pigment. Characterization of pigmented actinobacteria can be carried out using a polyphasic taxonomic approach. Pigmented actinobacteria belonging to the Microbiology Laboratory, Department of Biology FMIPA IPB are known to produce pigment secondary metabolites with antioxidant properties. However, the character of this isolate is not fully known. This research aims to characterize pigmented actinobacteria from the collection of the Microbiology Laboratory, Department of Biology FMIPA IPB through several polyphasic taxonomic approaches. The research stages include purification, growth and morphological characterization of actinobacterial colonies on various media, ability to grow on various carbon sources, identification of the 16S rRNA gene and bioinformatics analysis. Five isolates were able to grow optimally on ISP 2 media. The colony morphology of the five isolates was different on each medium. Four isolates belonged to the genus Streptomyces, while the other one belonged to rare-actinobacteria non-Streptomyces. Each isolate has the ability to grow on different carbon sources. The results of molecular identification of the 16S rRNA gene of HVB isolates showed an amplicon size of ~1465 bp which had a similarity of 91.62% to the species Rhodococcus wratislaviensis strain G119. Key words: actinobacteria, molecular, pigment, polyphasic taxonomy, rare actinobacteria
Keyword: actinobacteria, Molecular, pigment, polyfasic taxonomy, rare actinobacteria

Judul: Antimicrobial, Antioxidant, and Toxicity Activity of Marine Actinomycetes Biopigment Extract
Abstrak: Aktinomiset merupakan bakteri Gram-positif yang mempunyai potensi sebagai sumber metabolit sekunder baru. Salah satu metabolit sekunder tersebut adalah biopigmen. Biopigmen yang dihasilkan oleh aktinomiset mempunyai berbagai aktivitas biologis. Penelitian ini bertujuan menguji kemampuan antimikrob, antioksidan, dan toksisitas ekstrak biopigmen aktinomiset laut kode HV11.P3 dan SCA54.P2. Aktivitas antimikrob diuji terhadap beberapa mikrob patogen dan menunjukkan hasil terbaik dalam menghambat pertumbuhan Bacillus subtilis ATCC 19659 untuk ekstrak HV11.P3 kemudian Escherichia coli ATCC 8739 untuk SCA54.P2.Aktivitas antioksidan terhadap radikal DPPH menunjukkan nilai IC50 231,084 μg/ml untuk HV11.P3 dan 369,296 μg/ml untuk SCA54.P2. Hasil uji toksisitas berupa nilai LC50 yaitu 94,603 μg/ml untuk HV11.P3 dan 131,220 μg/ml untuk SCA54.P2 menggunakan metode Brine Shrimp Lethality Test (BSLT). Senyawa kimia penyusun ekstrak diidentifikasi menggunakan GC-MS. Hasilnya senyawa 1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl- (CAS) menjadi penyusun dominan ekstrak HV11.P3 dengan peak area 44,65% dan 5-Methoxypyrrolidin-2-one dengan luas peak area 30,23% untuk ekstrak biopigmen SCA54.P2. Analisis gen 16S rRNA menunjukkan bahwa HV11.P3 memiliki kesamaan terdekat dengan Micromonospora chalcea strain 1464-217L dan SCA54.P2 dengan Micromonospora tulbaghiae strain TVU1., Actinomycetes are Gram-positive bacteria that have potency as a source of new secondary metabolites. One of those secondary metabolites is biopigments. Biopigments produced by actinomycetes have various biological activities. This study aimed to determine antimicrobial, antioxidant, and toxicity activity from marine actinomycetes biopigment extract coded as HV11.P3 and SCA54.P2. Antimicrobial activities were tested against several pathogenic bacteria and showed the best result for inhibiting Bacillus subtilis ATCC 19659 for HV11.P3 and Escherichia coliATCC 8739 for SCA54.P2. The antioxidant activity against DPPH radical showed IC50 value 231,084 μg/ ml for HV11.P3 and 369,296 μg/ ml for SCA54.P2. The toxicity test results (LC50) based on Brine Shrimp Lethality Test (BSLT) were 94,603 μg/ ml and 131,220 μg/ ml for HV11.P3 and SCA54.P2, respectively. The major chemical compounds of HV11.P3 extract were identified as 1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl- (CAS) (peak area 44,65%) and 5-Methoxypyrrolidin-2-one for SCA54.P2 (peak area 30,23%). The 16S rRNA gene analysis showed that HV11.P3 had the closest similarity with Micromonospora chalcea strain 1464-217L and SCA54.P2 with Micromonospora tulbaghiae strain TVU1.
Keyword: BSLT, DPPH, Extract, GC-MS, 16S rRNA gene

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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