Judul: Metagenomic Analysis of Microalgae Consorsium in Java Coastal Ecosystem based on Shotgun Sequencing Method
Abstrak: Mikroalga merupakan mikroorganisme fotoautotrof potensial yang dapat dikembangkan menjadi sumber energi alternatif. Sebelumnya penelitian biodiversitas dan identifikasi telah dilakukan secara morfologi dan molekuler menggunakan primer 16S rRNA. Studi metagenomik ini bertujuan untuk menganalisis proporsi mikroalga prokariotik dan eukariotik serta komposisi mikroalga menggunakan metode Shotgun Sequencing. Sampel kultur mikroalga dari Pantai Glagah (L1), Pantai Pasongsongan (L2), Pantai Branta (L3), Balai Budidaya Mikroalga Jepara (L4), Pantai Bangsring (L5), dan Pantai Blekok (L6) disekuensing dengan metode NGS berupa shotgun sequencing. Kemudian data dianalisis secara metagenomik menggunakan platform Maser. Hasil klasifikasi ditemukan 8 famili, 23 genus, dan 18 spesies mikroalga prokariotik, serta 14 famili, 37 genus, dan 67 spesies mikroalga eukariotik. Jenis yang paling sering ditemui pada tingkat famili yaitu Bacillariophyceae dengan frekuensi 19%, tingkat genus yaitu Bacillus sebesar 30%, dan tingkat spesies adalah uncultured Chroococcidiopsis sp. sebesar 15,83%. Sampel Pantai Blekok (L6) adalah yang paling beragam komposisinya., Microalgae are potential photoautotrophic microorganism that can be developed as an alternative energy source. Previously, research on their biodiversity and identification had been carried out morphologically and molecularly using 16S rRNA primers. This metagenomic study aims to analyze the proportion of prokaryotic and eukaryotic microalgae and the composition of microalgae using the Shotgun Sequencing method. Microalgae culture samples from Glagah Beach (L1, Pasongsongan Beach (L2), Branta Beach (L3), Microalgae Cultivation Center Jepara (L4), Bangsring Beach (L5), and Blekok Beach (L6) were sequenced in NGS platform by shotgun-sequencing. Data were then analyzed metagenomically using the Maser platform. The classification results found 8 families, 23 genera, and 18 species of prokaryotic microalgae, as well as 14 families, 37 genera, and 67 species of eukaryotic microalgae. The most frequently encountered type at family level was Bacillariophyceae by 19% frequency, at genus level was Bacillus at 30%, and species level was uncultured Chroococcidiopsis sp. at 15.83%. The Blekok Beach sample (L6) is the most diverse in composition.
Keyword: eukaryotic, metagenomic, microalgae, prokaryotic, shotgun sequencing

Judul: Keragaman Mikroalga Berbasis Morfologi serta Teknik Isolasi dan Amplifikasi DNA Mikroalga dari Pantai Ujung Genteng
Abstrak: Identifikasi keragaman mikroalga berdasarkan morfologi dan molekuler baik dari air laut maupun air tawar telah banyak dipublikasikan. Pantai Ujung Genteng di Sukabumi yang memiliki karakteristik wilayah dengan tutupan padang lamun yang luas serta merupakan wilayah zona intertidal belum dilakukan penelitian tentang keragaman mikroalganya. Penelitian yang telah dilaksanakan ini bertujuan mengidentifikasi keragaman mikroalga yang bersumber dari air laut Pantai Ujung Genteng berdasarkan ciri morfologi serta mengembangkan teknik isolasi dan amplifikasi DNA mikroalga. Pengambilan sampel dilakukan sebanyak tiga kali pada 3 lokasi penelitian yang telah ditentukan. Metode yang dilakukan adalah purposive sampling sebanyak 10 liter air laut dan dianalisis di Laboratorium Fisiologi dan Biologi Molekuler Tumbuhan, identifikasi morfologi menggunakan mikroskop binokuler, isolasi dan amplifikasi DNA menggunakan marka 18S rDNA. Berdasarkan hasil identifikasi morfologi jumlah spesies yang ditemukan di Pantai Ujung Genteng adalah 47 spesies yang mencakup 6 kelas mikroalga. Hasil uji kualitas DNA menggunakan PCR dan elektroforesis dapat memunculkan pita DNA yang mengindikasikan bahwa tahapan amplifikasi DNA mikroalga berhasil dilakukan, meskipun hanya satu dari tujuh sampel DNA yang diisolasi., The identification of microalgae diversity based on morphology and molecules from both seawater and fresh water has been widely published. Ujung Genteng Beach in Sukabumi, which has the characteristics of an area with extensive seagrass cover and is an intertidal zone, has not been studied on the diversity of microalgae. The research that has been carried out is aimed at identifying the diversity of microalgae sourced from seawater at Ujung Genteng Beach based on morphological characteristics and developing techniques for isolation and amplification of microalgae DNA. Sampling was carried out three times at 3 predetermined research locations. The method used was purposive sampling of 10 liters of seawater and analyzed in the Laboratory of Physiology and Plant Molecular Biology, morphological identification using a binocular microscope, isolation and DNA amplification using 18S rDNA markers. Based on the results of morphological identification, the number of species found at Ujung Genteng Beach is 47 species which includes 6 classes of microalgae. The results of DNA quality tests using PCR and electrophoresis can reveal DNA bands indicating that the microalgae DNA amplification step was successful, although only one of the seven DNA samples was isolated.
Keyword: diversity, microalgae, molecular, morphological, seawater

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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