Judul: Karakterisasi Enzim dan Kloning Gen Penyandi Mananase dari Bacillus subtilis Asal Tempe
Abstrak: Nutrition value and characteristics of tempe are primarily derived from enzymatic activities derived from complex microorganisms community during its fermentation. As a rich source of bacterial diversity, tempe could be explored for its potential to yield enzyme, such as mannanase. This study was intended to isolate mannanase producing bacteria derived from a number of tempe samples from Java (Bogor, Surabaya, Malang, Kediri, Lamongan, and Wonogiri); characterize its enzyme; and clone its mannanase gene into E. coli. Crude enzyme from each isolate was prepared for characterization. Showed the highest specific activity (0,41 U/mg protein), isolate N mannanase was further characterized. Nmannanase crude enzyme showed optimum activity at 60oC and pH 5.0. This enzyme has better activity in palm kernel meal (PKM) as its substrate with average activity 1.13 U/ml compared to soybean meal (SBM) (0.43 U/ml) and copra meal (CM) (0.48 U/ml). This enzyme was also stable at 60oC for 4 hours, in wide range of pH (4-10) for 1 hour, and various metal ions. SDS-PAGE and Zymogram analysis showed that this mannanase has molecular weight approximately 39.8 kilodalton. Isolate N was identified having 98% similarity with Bacillus subtilis (Genebank access JN644507) employing 16S rRNA sequence analysis. The B. subtilis N-mannanase gene was successfully isolated and cloned into E.coli. Recombinant’s mannanase activity was detected in E. coli intra- (8.82 U/ml) and extracellular (6.39 U/ml) extracts.
Keyword: 

Judul: Isolasi Dan Karakterisasi Enzim Mananase Bacilius pumilus DYP 2
Abstrak: Mananase adalah enzim pmgurai senyawa manan yang banyak dihasilkan oleh mikroorganisme termasuk bakteri. Enzim ini dapat dimanfilatkan pada berbagai macam proses industri dan untuk meningkatkan nilai gizi pakan temak. Penelitian ini bertujuan untuk mmgisolasi dan mmgkaraictl'2"isasi enzim mananase dari sampel tanah limbah kopra asal kabupaten Pasaman Swnatra Barat Penelitian diawali dengan mengisolasi bakte:ri dari sampeJ tanah dan menwnbuhkannya pada medium gum locust bean, lsolatisolat yang didapat diukur indeks mananolitiknya. Isolat dengan indeks mananolitik terbesar digunakan untuk membuat inokulum dan juga untuk diidentifikasi berdasarkan analisis 16S rRNA. Inokulum digWIakan Wltuk memproduksi enzim mananase. Enzim tersebut diuji aktivitasnya dengan menggunakan metode Purwadaria et al. (1994) dengan modifikasi pH 7.2. Kadar protein diukur berdasarkan metode Bradford (1976). Karakterisasi enzim dilakukan pada berbagai pH dan suhu serta dilakukan uji kestabilan aktivitas enzim. Isolasi balderi dari sampeJ tanah asal Kabupaten Pasaman Sumatra Barat menghasilkan 27 isolat dengan 4 isolat ter-baik. Isolat DYP 2 dengan indeks mananolitik terbesar yaitu 16 diidentifikasi sebagai Bacillus pumiJus. B. pumilus tersebut memmjukkan aktivitas enzim mananase optimum pada saat jam ke-24 dengan nilai 0.079 mU/mt. Pada saat aktivitas optimum didapat kadar protein sebesar 0.4 mglml dan aktivitas spesifik sebesar 0.2 mU/mg. Enzim mSllIlIlase dati B. pumilus DYP 2 memiliki suhu optimum 800c, aktivitas enzim tertinngi pada pH 3.00, dan stabil selama
Keyword: 

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.
Keyword: