Judul: Identification and Total of Lactic Acid  Fermentative Bacteria in Sumatran Orangutan (Pongo abelii)
Abstrak: Bakteri asam laktat (BAL) merupakan bakteri yang digolongkan ke dalam bakteri yang bermanfaat bagi kesehatan inang, terutama menjaga keseimbangan flora di dalam pencernaan. Penelitian ini bertujuan melakukan isolasi dan identifikasi jenis bakteri asam laktat serta mengetahui jumlah koloninya pada feses orang utan sumatra. Sampel dilakukan pengenceran 10-1 hingga ke 10-8, kemudian diisolasikan ke dalam media selektif MRS agar menggunakan metode pour plate. Setelah diinkubasi, koloni yang tumbuh pada media diamati dan dihitung total koloni bakteri asam laktat. Koloni yang terpilih dilanjutkan untuk diisolasi dan diidentifikasi menggunakan uji sederhana, yaitu uji biokimia dengan uji katalase, uji oksidase, uji Sulfide Indole Motility, uji Methyl Red-Voges Proskauer, dan uji fermentasi gula-gula. Bakteri asam laktat yang dapat diidentifikasi dari sampel feses orang utan sumatra adalah Leuconostoc sp., Weissella sp., Lactobacillus sp. Hasil penelitian menunjukkan total bakteri asam laktat pada sampel sebesar 8,98 x 106 CFU/ml., Lactic acid bacteria (LAB) is a type of bacteria which belong to have beneficial health for the host, especially to maintain microflora stability of the digestion. This research aimed to isolate and identify the lactic acid bacteria in the fecal of sumatran orangutan. Samples were dilution 10-1 to 10-8, then isolated in selected media MRSA using the pour plate method. After the incubation, separated colonies which grown in media were observed and were counted as a total colony of lactic acid bacteria. The selected colony continued to isolate and identify using simple tests, such as biochemical test with catalase test, oxidase test, Sulfide Indole Motility (SIM) tests, Proskauer's Methyl Red-Voges test, and carbohydrate fermentation test. Lactic acid bacteria that can be identified from fecal samples of sumatran orangutan are Leuconostoc sp., Weissella sp., dan Lactobacillus sp. The results showed that the total lactic acid bacteria in the sample was 8,98 x 106 CFU/ml.
Keyword: lactic acid bacteria, fecal sumatran orangutan, total plate count

Judul: Identification and Total of Lactic Acid Fermentative Bacteria in Primate Feces
Abstrak: Bakteri asam laktat (BAL) bermanfaat bagi kesehatan, terutama peranannya sebagai probiotik dan antimikroba dalam pengobatan penyakit saluran pencernaan pada primata. Penelitian ini bertujuan untuk mengidentifikasi serta menghitung total koloni bakteri asam laktat pada feses lima jenis primata yaitu orang utan, owaungko hitam, owa ungko coklat, siamang, dan lutung yang dikoleksi dari Kebun Binatang Bukittinggi. Sampel dilakukan pengenceran 10-1 hingga ke 10-7 dandiinokulasikan ke dalam media selektif MRSA (de Man Rogosa Sharpe Agar) dengan metode pour plate. Koloni bakteri asam laktat yang tumbuh pada media diamati dan dihitung total koloninya. Koloni terpilih diisolasi untuk selanjutnya diidentifikasi menggunakan beberapa uji biokimia yaitu uji katalase, uji oksidase, uji Sulfide Indol Motility, uji Methyl Red-Voges Proskauer, dan uji fermentasi karbohidrat. Penelitian berhasil mengisolasi bakteri dari genus Lactobacillus, Leuconostoc, dan Weissella. Hasil penelitian menunjukkan orang utan menghasilkan total bakteri asam laktat tertinggi yaitu sebesar 3,1 x 108 CFU/ml., Lactic acid bacteria (LAB) are beneficial for health, especially their role as probiotics and antimicrobials in the treatment of digestive tract diseases in primates. This research aims to identify and count the total colonies of lactic acid bacteria in the feces of five primate species, namely orangutans, black gibbons, brown gibbons, siamang, and langurs collected from the Bukittinggi Zoo. Samples were diluted 10- 1 to 10-7 and inoculated into MRSA (de Man Rogosa Sharpe Agar) selective media using the pour plate method. Colonies of lactic acid bacteria growing on the media were observed and the total colonies were counted. Selected colonies were isolated for further identification using several biochemical tests, namely catalase test, oxidase test, Sulfide Indole Motility test, Methyl Red-Voges Proskauer test, and the carbohydrate fermentation test. The results of the research succeeded in isolating lactic acid bacteria from the genera Lactobacillus, Leuconostoc, and Weissella. Orangutans produced the highest total lactic acid bacteria, which was 3.1 x 108 CFU/ml.
Keyword: lactic acid bacteria, primates, total plate count

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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