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: Characterization of Lactic Acid Bacteria Isolated from Sumatran Orangutan (Pongo abelii) as Probiotic Candidate
Abstrak: Penggunaan probiotik sebagai alternatif dari antibiotik saat ini mulai dikembangkan karena mampu memberikan keuntungan bagi kesehatan orang utan. Probiotik yang tergolong sebagai Bakteri Asam Laktat (BAL) mampu menjadi antioksidan, antikanker, imunomodulator, serta antiinflamasi. Penelitian ini bertujuan mengidentifikasi dan karakterisasi BAL pada orang utan sumatra (Pongo abelii) sebagai kandidat probiotik. Sampel yang digunakan berasal dari masing-masing 5 feses orang utan sumatra Taman Nasional Gunung Leuser dan Taman Safari Indonesia. Feses diinokulasikan pada media selektif MRSA (de Man Rogosa Sharpe Agar). Koloni-koloni yang tumbuh lalu dimurnikan. Koloni tumbuh lalu diidentifikasi melalui pewarnaan Gram dan uji biokimia. Koloni teridentifikasi BAL dilakukan karakterisasi probiotik mencakup uji ketahanan garam NaCl (NaCl 2%, 4%, dan 6,5%), uji ketahanan pH (pH 2 dan pH 3), serta uji ketahanan garam empedu (MRS Bile Salt Broth 0,3% dan 1%). Hasil penelitian menunjukkan dari 28 isolat teridentifikasi jenis bakteri sebanyak 26 isolat. Sebanyak 22 isolat BAL dilanjutkan untuk pengujian karakterisasi probiotik. Hasil karakterisasi pada 22 isolat BAL menunjukkan sebanyak 12 isolat, mencakup 6 genus yang mengarah spesifik pada 8 spesies, memiliki karakter sebagai kandidat probiotik yakni Macrococcus sp., Lactobacillus sp., Streptococcus sp., Weissella sp., Pediococcus sp., dan Aerococcus spp. Sebanyak 10 isolat lainnya berpotensi sebagai probiotik namun perlu ditinjau kembali., The use of probiotics as an alternative to antibiotics is currently being developed due to their benefits to orangutans’ health. Probiotic bacteria classified as Lactic Acid Bacteria (LAB) are capable of being antioxidants, anticancer, immunomodulators, and anti-inflammatories. This study aims to identify and characterize LAB in Sumatran orangutan (Pongo abelii) as probiotic candidates. The samples used are from the feces of each 5 individuals of Sumatran orangutans from Taman Safari Indonesia and Gunung Leuser National Park. The feces inoculated to a selective media MRSA (de Man Rogosa Sharpe Agar). The growing colonies were then purified on a separate MRSA and then incubated. Growing colonies were identified through Gram staining and biochemistry test. Colonies identified as LAB were then subjected to probiotic characterization including NaCl salt resistance tests (NaCl 2%, 4%, and 6.5%), pH resistance tests (pH 2 and pH 3), and bile salt resistance tests (MRS Bile Salt Broth 0, 3% and 1%). The results showed that from 28 isolates, 26 of them is identified into species of bacteria. The amount of 22 isolates identified as LAB then were continued to the probiotic characterization test. The characterization results showed the 12 isolates, which consist of 6 genus that specifically led to 8 species, presented the probiotic candidate characters which were Macrococcus sp., Lactobacillus sp., Streptococcus sp., Weissella sp., Pediococcus sp., and Aerococcus spp. Other 10 isolates were also potential as probiotics but needed to be reviewed.
Keyword: lactic acid bacteria, Pongo abelii, probiotic, sumatran orangutan

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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