Judul: Identification of Gram Negative Bacteria and E. coli Antimicrobial Susceptibility Test on Sumatran Orang Utan in Taman Nasional Gunung Leuser
Abstrak: Orang utan merupakan satwa endemik Indonesia yang keberadaannya terancam punah. Salah satu penyakit yang sering menginfeksi orang utan liar adalah penyakit pencernaan yang disebabkan oleh bakteri patogen yang tergolong bakteri Gram negatif. Penyakit infeksi yang disebabkan oleh bakteri dapat diobati dengan antibiotik, namun penggunaannya terkadang kurang efektif karena resistansi antibiotik. Identifikasi bakteri Gram negatif dan uji kepekaan antibiotik pada studi ini perlu dilakukan untuk mengetahui bakteri yang terkandung dalam feses orang utan serta mengetahui antibiotik yang masih sensitif dan yang telah resistan terhadap bakteri Escherichia coli. Bakteri pada feses orang utan diisolasi pada media agar EMBA dan MCA dan diidentifikasi menggunakan uji pewarnaan Gram dan beberapa uji biokimia, mulai dari uji oksidase, uji fermentasi karbohidrat, uji urea, uji TSIA, uji motilitas dan uji IMViC. Uji kepekaan antibiotik dilakukan dengan uji difusi dengan metode Kirby Bauer terhadap 12 antibiotik. Hasil dari identifikasi bakteri Gram negatif ditemukan bakteri Yersinia sp., Citrobacter sp., Escherichia coli, Escherichia vulneris, Klebsiella spp., Stenotrophomonas maltophilia, dan Kluyvera sp.. Isolat bakteri Escherichia coli yang diuji terhadap 12 antibiotik menunjukkan hasil masih peka atau sensitif terhadap antibiotik amoksisilin, tetrasiklin, oksitetrasiklin, doksisiklin, gentamisin, streptomisin, kloramfenikol, siprofloksasin, asam nalidiksat, dan enrofloksasin., Orang utans are Indonesian’s endemic animal which are threatened by extinction. One of the diseases that often infects wild orang utans is digestive disease caused by pathogenic bacteria belonging to Gram-negative bacteria. Infectious diseases caused by bacteria can be treated with antibiotics, but the usage is less effective from time to time because of antibiotic resistancy. Identification of Gram negative bacteria and antibiotic susceptibility tests in this study need to be carried out to determine the bacteria contained in orang utan feces and antibiotics that are still susceptible to Escherichia coli bacteria. Bacteria in orang utan feces were isolated on EMBA and MCA agar media and identified using Gram stain test and several biochemical tests, starting from the oxidase test, carbohydrate fermentation test, urea test, TSIA test, motility test and IMViC test. Antibiotic susceptibility test was carried out by diffusion test using the Kirby Bauer method on 12 antibiotics. The results of the identification of Gram-negative bacteria were Yersinia sp., Citrobacter sp., Escherichia coli, Escherichia vulneris, Klebsiella spp., Stenotrophomonas maltophilia, and Kluyvera sp.. The isolate of Escherichia coli bacteria tested against 12 antibiotics showed that it were susceptible to amoxicillin, tetracycline, oxytetracycline, doxycycline, gentamycin, streptomycin, chloramphenicol, ciprofloxcacin, nalidixid acid, and enrofloxacin.
Keyword: bakteri Gram negatif, Escherichia coli, orang utan liar, kepekaan antibiotik

Judul: Identification of Gram Positive Bacteria and Staphylococcus aureus Sensitivity Test to Antibiotics on Wild Sumatran Orangutans
Abstrak: Orang utan rentan terinfeksi gangguan pencernaan yang disebabkan oleh bakteri Gram positif, penanganan dengan pemberian antibiotik yang berlebihan dapat menyebabkan resistensi. Penelitian ini bertujuan untuk mengisolasi dan mengidentifikasi bakteri Gram positif yang terdapat pada feses orang utan sumatra liar yang berasal dari Taman Nasional Gunung Leuser Kabupaten Aceh Tenggara Provinsi Aceh, serta mengetahui jenis antibiotik yang masih sensitif dan sudah resistan terhadap bakteri Staphylococcus aureus. Metode penelitian ini terdiri dari koleksi dan isolasi sampel, identifikasi bakteri melalui pewarnaan Gram dan uji biokimia seperti KOH 3%, oksidase, katalase, indol, VP, glukosa mikroaerofilik, isolasi pada MSA, dan fermentasi karbohidrat, serta uji kepekaan antibiotik dengan metode difusi cakram atau disk diffusion Kirby Bauer. Proses isolasi dan identifikasi menemukan terdapat tujuh bakteri yang berasal dari orang utan sumatra liar dan teridentifikasi sebagai Staphylococcus aureus, Staphylococcus caseolyticus, Staphylococcus epidermidis, Bacillus megaterium, Bacillus lentus, dan Bacillus sphaericus. Bakteri Staphylococcus aureus yang ditemukan pada feses orang utan Sumatra liar telah resisten terhadap ampisilin, amoksisilin, dan eritromisin dan masih sensititif terhadap gentamisin, siprofloksasin, asam nalidiksat, oksitetrasiklin, doksisiklin, enrofloksasin, dan kloramfenikol., Orangutans are susceptible to digestive infection caused by Gram-positive bacteria, treating them with excessive antibiotics can cause resistance. This study aims to isolate and identify Gram-positive bacteria found in the feces of wild sumatran orangutans from Gunung Leuser National Park, Southeast Aceh and to determine which types of antibiotics are already resistant and still sensitive to Staphylococcus aureus. This research method consists of sampling and isolation, identification of bacteria through Gram staining and biochemical tests such as 3% KOH, oxidase, catalase, indole, VP, microaerophilic glucose, isolation in MSA, and carbohydrate fermentation, also disc diffusion or Kirby Bauer's diffusion disc method is being used to antibiotic susceptibility test. The isolation and identification process found that there were seven bacteria from the wild sumatran orangutans and identified as Staphylococcus aureus, Staphylococcus caseolyticus, Staphylococcus epidermidis, Bacillus megaterium, Bacillus lentus, and Bacillus sphaericus. Staphylococcus aureus found in the feces of wild sumatran orangutans have been resistant to ampicillin, amoxicillin, and erythromycin and are still sensitive to gentamicin, ciprofloxacin, nalidixic acid, oxytetracycline, doxycycline, enrofloxacin, and chloramphenicol.
Keyword: bakteri Gram positif, orang utan liar, resistansi antibiotik, Staphylococcus aureus

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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