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: Analisis Metagenomik Mikroalga Prokariot dari Perairan Laut Jawa Timur
Abstrak: Mikroalga adalah kumpulan mikroorganisme uniseluler yang dapat berfotosintesis dan menjadi alternatif bioenergi yang potensial untuk dikembangkan. Sebelumnya, penelitian mengenai boidiversitas mikroalga di laut Jawa Timur telah dilakukan secara morfologis. Penelitian ini bertujuan menganalisis metagenomik mikroalga prokariot di perairan laut Jawa Timur. Sampel dari penelitian sebelumnya, yang berasal dari Madura (M3, M4, M6, M9), Banyuwangi (BW) dan Situbondo (ST), dikulturkan kemudian disekuensing dengan metode NGS (Next Generation Sequencing) menggunakan primer 16S rRNA. Data sekuens dianalisis menggunakan Geneious Prime 2020.1.2 dengan mengacu pada database 16S microbial dari NCBI. Terdapat 6 ordo dan 17 spesies teridentifikasi dari divisi Cyanobacteria. Ordo Oscillatoriales terdapat pada seluruh sampel dengan rata-rata frekuensi 43,25%. Crocosphaera watsonii dan Laspinema etoshii terdapat pada kelima sampel kecuali M6. Situbondo memiliki spesies paling banyak yaitu 16 spesies sedangkan M6 hanya memiliki satu spesies. Indeks keanekaragaman tergolong rendah hingga sedang, sedangkan indeks dominansi tergolong rendah hingga tinggi., Microalgae are mixture of unicellular photoautotroph organisms and have big potential to be developed as an alternative bioenergy. Previous research has been carried out on the diversity of microalgae from East Java Coastal Area using morphological identification. This study aims to analyze the prokaryotic microalgae diversity using metagenomics approach. Seawater samples from previous studies, which came from Madura (M3, M4, M6, and M9), Banyuwangi (BW) and Situbondo (ST), were cultured and then sequenced by NGS applying 16S rRNA primers. Analysis was carried using the Geneious Prime 2020.1.2 program referring to the 16S microbial database from NCBI. There are 6 orders and 17 species classified from the Cyanobacteria division. The Oscillatoriales order is found in all samples with an average frequency of 43,25%. Crocosphaera watsonii and Laspinema etoshii were found in five samples, except M6. Situbondo had the most species, namely 16 species, while the M6 sample only had 1 species. Diversity index is classified as low to moderate, while the dominance index is classified as low to high.
Keyword: 16S rRNA, Cyanobacteria, metagenomics, microalgae, prokaryotes

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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