Judul: Enzyme Activity of β-1,3-Glucanase from Streptomyces spp. Rhizosphere and Cloning of its Encoding Gene
Abstrak: Enzim β-1,3-glukanase merupakan salah satu enzim yang mampu menghidrolisis glukan penyusun dinding sel cendawan fitopatogen. Aktinomiset rizosfer jagung dari kelompok Streptomyces spp. diduga mampu memproduksi enzim yang memiliki aktivitas glukanolitik dan berpotensi untuk dikembangkan sebagai agen biokontrol cendawan fitopatogen. Penelitian ini bertujuan menganalisis aktivitas enzim glukanase secara kuantitatif dua isolat Streptomyces spp. dengan indeks glukanolitik tertinggi pada penelitian sebelumnya dan mengidentifikasi gen penyandinya. Metode penelitian yang dilakukan meliputi uji aktivitas glukanase secara kuantitatif, amplifikasi gen endo-β-1,3-glukanase (bglS), kloning, konfirmasi hasil kloning, sekuensing, analisis fenetik, dan prediksi model protein. Aktivitas spesifik enzim isolat S. collinus ARJ38 lebih tinggi dari S. tritolerans ARJ32, yakni sebesar 41,599 U/mg pada waktu inkubasi hari ke-8. Keberadaan gen penyandi bglS pada kedua isolat berhasil diamplifikasi dan dikloning. Hasil sekuensing gen bglS parsial dari kedua isolat potensial teridentifikasi sebagai endo-β-1,3-glukanase dari kelompok glycoside hydrolase (GH) family 16. Model struktur tiga dimensi yang dikonstruksi dari sekuens asam amino bglS parsial memiliki parameter kualitas serta kemiripan yang tinggi dengan model protein eksperimental endo-β-1,3-glukanase parsial dari Nocardiopsis sp. F96., The β-1,3-glucanase enzyme is one of the enzymes capable of hydrolyzing the glucan components of phytopathogenic fungal cell walls. Streptomyces spp. isolated from the maize rhizosphere are suspected to produce enzymes with glucanolytic activity and have the potential to be developed as biological controlling agents against phytopathogenic fungi. This study aims to quantitatively analyze the enzymatic activity of glucanase in two Streptomyces spp. isolates with the highest glucanolytic index from previous research, and to identify their encoding genes. The research methods include quantitative analyze of the glucanase activity, amplification of the endo-β-1,3-glucanase (bglS) gene, cloning, confirmation of cloning results, sequencing, phenetic tree analysis, and protein model prediction. The specific activity enzyme of S. collinus ARJ38 was higher than that of S. tritolerans ARJ32, with a value of 41.599 U/mg on the 8th day of incubation. The presence of the bglS gene in both isolates was successfully amplified and cloned. The sequencing results of the bglS gene from both potential isolates were identified as endo-β-1,3-glucanase from the glycoside hydrolase family 16. The three-dimensional structure model constructed from the partial bglS amino acid sequence exhibited high-quality parameters and high similarity with the experimental protein model of partial endo-β-1,3-glucanase from Nocardiopsis sp. F96.
Keyword: glucanase, phenetic analysis, protein model, rhizosphere actinomycetes, TA cloning, aktinomiset rizosfer, fenetik, glukanase, model protein

Judul: Production of ß-1,3-Glucanase Enzyme from  Streptomyces sp. Antifungal Phytopathogens on Several Mediums and  Determination of its Activity
Abstrak: Enzim ß-1,3-glukanase merupakan enzim hidrolitik yang mampu mendegradasi ß-glukan penyusun dinding sel cendawan fitopatogen. Enzim ini dapat diproduksi Streptomyces tritolerans ARJ 32 dan Streptomyces collinus ARJ 38 dan berpotensi sebagai fungisida alami. Namun, produksi enzim ini membutuhkan media produksi yang relatif mahal. Oleh karena itu, penelitian ini bertujuan memproduksi enzim ß-1,3-glukanase dari S. tritolerans ARJ 32 dan S. colinus ARJ 38 antifungi fitopatogen pada beberapa medium dan menentukan aktivitasnya. Kuantifikasi aktivitas enzim ß-1,3-glukanase menunjukan nilai aktivitas tertinggi kedua Streptomyces sp. yang dikulturkan di media ekstrak ubi jalar, yakni sebesar 32,970 U/mg (S. tritolerans ARJ 32) dan 80,410 U/mg (S. collinus ARJ 38). Nilai aktivitas enzim ß-1,3-glukanase ini menunjukkan bahwa ekstrak ubi jalar berpotensi digunakan sebagai media alternatif produksi enzim ß-1,3-glukanase. Streptomyces sp. memiliki aktivitas antifungi terhadap F. oxysporum dan R. solani dengan penghambatan 23,96% dan 32,52% (ARJ 32) dan 21,88% dan 37,40% (ARJ 38)., ß-1,3-Glucanase enzyme is a hydrolytic enzyme capable of degrading ß-glucan constituting fungi cell wall. This enzyme can be produced by Streptomyces tritolerans ARJ 32 and Streptomyces collinus ARJ 38 and has potential as a natural fungicide. However, the production of this enzyme requires relatively expensive ingredients. Therefore, this study aimed to produce ß-1,3-glucanase enzymes from S. tritolerans ARJ 32 and S. colinus ARJ 38 against phytopathogenic fungi on several media and determining their activity. Quantification of glucanase enzyme activity showed the highest activity of both Streptomyces sp. cultured in sweet potato extract broth media, with 32,970 U/mg (S. tritolerans ARJ 32) and 80,410 U/mg (S. collinus ARJ 38). These results shows that sweet potato extract is potentially an alternative media production for ß-1,3-glucanase enzyme production. Streptomyces sp. had antifungal activity against F. oxysporum and R. solani with inhibition of 23,96% and 32,52% (ARJ 32) and 21,88% and 37,40% (ARJ 38).
Keyword: antifungi, molase, Ubi jalar, enzim ß-1,3-glukanase, kentang

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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