Judul: Karakteristik Penempelan Dan Koagregasi Bakteri Asam Laktat Indigenous Dadiah Dan Yogurt Sebagai Kandidat Probiotik Pada Usus Halus Tikus in vitro
Abstrak: Dadiah is a traditional food from West Sumatra. That made from buffalo milk and ripened in bamboo and covered with banana leaves. One of the criterions of probiotic bacteria is its ability to adhere on the mucosa of intestine. The aims of this research were to identify the characteristic of indigenous dadiah lactid acid bacterias (LABs) (Lactobacillus acidophilus Y-01, Bifidobacterium longum Y-01) and lactid acid bacteria from yoghurt (Lactobacillus plantarum D-01 and Lactococcus lactis D- 01) as probiotic through its abilities to adhere on intestine mucosa of rats (adhesi) and to coaggregate between probiotic bacterias candidate. Probiotic bacterias candidate were tested for aggregation, autoaggregation, coaggregation, adhesion on the intestinal mucosa of rats and attachment on stainless steel plate by in vitro tests. Research showed that indigenous dadiah LABs and LABs from yoghurt had ability to adhere on intestinal mucosa of rat and attache on stainless steel plate. The average number of LABs attached on stainless steel plate was 5 log10 CFU/cm2 of average initial bacterial population of 8 log10 CFU/ml. The highest of LABs attached on stainless steel plate was found from L. lactis D-01 that was equal to 5,80 log10 CFU/cm2. Indigenous dadiah LABs and LAB from yoghurt cows had a positive aggregation value proven by the sediment existence. The average of percentage bacterial autoaggregation value was in weak position and fluctuated during the five hours of testing. The coaggregation test found that the lowest coaggregation percentage was between L. lactis D-01 and L. acidophilus Y-01, that showed by the value was 0,16%., Dadiah merupakan salah satu makanan tradisional hasil fermentasi alami dari susu kerbau yang terkenal di Sumatera Barat. Hasil isolasi terhadap dadiah mendapatkan dominasi Lactococcus lactis dan Lactobacillus plantarum. Produk susu fermentasi lain yang cukup dikenal masyarakat Indonesia adalah yogurt. Bakteri asam laktat yang berhasil diisolasi dari yogurt susu sapi diantaranya Bifidobacterium longum dan Lactobacillus acidophilus. Penelitian mengenai bakteri asam laktat asal dadiah susu kerbau dan asal yogurt susu sapi sebagai kandidat probiotik sudah dilakukan, khususnya tentang karakteristik pertumbuhannya secara in vitro dalam keasaman lambung, toleransinya pada garam empedu dan kemampuan antagonistiknya terhadap bakteri patogen (Sunaryo, 2011). Salah satu kriteria lain untuk memenuhi persyaratan sebagai kandidat bakteri probiotik yang menarik untuk diteliti adalah kemampuan bakteri asam laktat untuk menempel pada permukaan usus halus secara in vitro serta sifat koagregasinya terhadap bakteri asam laktat yang lain, bila digunakan sebagai mixted culture. Manfaat probiotik pada kesehatan saluran pencernaan telah banyak diteliti khususnya untuk mencegah dominasi bakteri patogen pada saluran pencernaan. Penelitian ini bertujuan untuk mempelajari kemampuan penempelan bakteri asam laktat indigenous dadiah (Lactobacillus plantarum D-01 dan Lactococcus lactis D-01) dan asal yogurt susu sapi (Lactobacillus acidophilus Y-01 dan Bifidobacterium longum Y-01) pada usus halus tikus secara in vitro serta kemampuan koagregasi antar bakteri untuk diidentifikasi sebagai probiotik. Penelitian ini berlangsung dari bulan Mei sampai November 2010 bertempat di Laboratorium Mikrobiologi Bagian Teknologi Hasil Ternak, Laboratorium Lapang Pemuliaan dan Genetika, Laboratorium Terpadu, Departemen Ilmu Produksi dan Teknologi Peternakan, Fakultas Peternakan serta Laboratorium Histologi, Departemen Anatomi, Fisiologi dan Farmakologi, Fakultas Kedokteran Hewan, Institut Pertanian Bogor. Materi yang digunakan meliputi BAL indigenous dadiah (L.
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Judul: Identifikasi Dan Karakterisasi Substrat Antimikroba Dari Bakteri Asam Laktat Kandidat Probiotik Yang Diisolasi Dari Dadiah Dan Yogurt
Abstrak: Probiotic has been defined as living microorganism that, when administered in adequate of amounts, confered a health benefit on the host. One of criterias that must be fulfilled by lactic acid bacteria as a probiotic is its ability to produce antimicrobial compounds that were capable inhibit toward pathogenic bacterias. Lactic acid bacteria (LAB) can be isolated from fermented milk. Maheswari (2008) isolated Lactobacillus plantarum D-01 and Lactococcus lactis D-01 from buffalo milk fermented called ‘dadiah’ traditionally produced by people from West and North Sumatra, and also isolated Bifidobacterium longum Y-01 and Lactobacillus acidophilus Y-01 from yogurt. Their potential as probiotic culture was interested to determine especially for their ability to produce antimicrobial substrate that inhibit pathogenic bacterias. Identification of nature and characterization of antimicrobial substrate produce by LABs tested for its stability at different pH and storage’s temperature, and proteolitic’s enzyme by agar well diffusion method. The culture supernatants inhibited toward Salmonella Ser. Typhimurium ATCC 14028, Escherichia coli ATCC 25922, and Staphylococcus aureus ATCC 25923. The supernatants showed an antimicrobial activity against phatogenic bacteria and identified as organic acid and hydrogen peroxide. The existance of proteinaceous antibacterial compound, which referred as bacteriosin, was proved through proteolityc activity on supernatants that resulted in decrease of zone inhibition diameters. Characterization determined that proteinaceous antibacterial compound was stable at room storage temperature within five days and at cold storage temperature within two weeks. Meanwhile, proteinaceous antibacterial compounds were not heat stable and not stable when adjusted in different pH, especially when adjusted in pH above 5. Four LABs tested could be considered as probiotic bacterias because all of LABs produced antimicrobial compounds consist of organic acid, hydrogen peroxide and bacteriosin that inhibited pathogenic indicator bacterias.
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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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