Judul: Studi senyawa bioaktif eksopolisakarida Pleurotus ostreatus pada media cair dengan berbagai macam sumber karbon
Abstrak: Pleurotus ostreatus merupakan salah satu jenis jamur yang mampu mensintesis metabolit sekunder berupa senyawa bioaktif eksopolisakarida sebagai respon terhadap lingkungannya (Chang dan Miles 1989). Senyawa bioaktif eksopolisakarida ini sangat bermanfaat dalam bidang kesehatan diantaranya dapat berfungsi sebagai antimikrob, antioksidan, antitumor dan lain-lain. Penelitian ini terdiri dari produksi P. ostreatus pada media cair MCM (Mushroom Complete Medium) dengan sumber karbon yang berbeda yaitu glukosa; maltosa; laktosa dan pati, pengukuran pH media, pengukuran bobot kering miselium dan pengukuran konsentrasi senyawa bioaktif eksopolisakarida (metode fenol sulfat). Selain itu dilakukan juga pengkarakterisasian senyawa bioaktif eksopolisakarida yang meliputi sifat antimikrob spektrofotemetri) dan antioksidan (metode ẞ-karoten/asam linoleat). (metode Hasil penelitian menunjukkan bahwa penumbuhan P. ostreatus pada media cair dengan berbagai macam sumber karbon memberikan pengaruh terhadap pertumbuhan P. ostreatus dan biosintesis senyawa eksopolisakarida. Dari 4 macam sumber karbon yang digunakan sumber karbon maltosa memberikan bobot kering miselium dan produksi senyawa bioaktif eksopolisakarida tertinggi sebesar 0.3532 g pada hari ke-24 dan 100.0000 mg/L pada hari ke-8. Sumber karbon maltosa juga memberikan aktivitas antimikrob tertinggi untuk E. coli, B. subtilis dan S. cerevisiae serta antioksidan tertinggi dengan nilai persentase sisa pemucatan ẞ-karoten sebesar 98.32% dibandingkan dengan sumber karbon laktosa, glukosa dan pati.
Keyword: 

Judul: Optimisasi Produksi dan Aktivitas Senyawa Eksopolisakarida dari Jamur Tiram Putih (Pleurotus ostreatus) pada Media Cair
Abstrak: White oyster mushroom (Pleurotus ostreatus) is one of high level fungal and contains exopolysaccharide that has antioxidant and antimicrobial activities. This type of mushrooms can be grown in a liquid medium with the availability of carbon and nitrogen sources. The liquid media was optimized to produce optimum exopolysaccharides. The culture of white oyster mushroom stem was first rejuvenated in potato dextrose agar medium, then grown in liquid mushroom complete medium with various type of carbon and nitrogen sources for the production of exopolysaccharide and continued with the test for antimicrobial and antioxidant activities of the exopolysaccharides. Sucrose and yeast extract were the best source of carbon and nitrogen, producing 208 and 100 mg/L exopolysaccharides, respectively. The optimum incubation time was 15 days, producing 527 mg/L exopolysaccharides. The exopolysaccharides exhibited antimicrobial activity against Bacillus subtilis a
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: