Judul: Memanfaatkan ragi probiotik multifungsi dari dadih, produk fermentasi tradisional dari Sumatera Barat,Indonesia
Abstrak: Fermented buffalo milk, commonly called Dadih, contains potential probiotic yeast cells. Probiotic yeast has garnered increasing attention in basic and clinical science over the past 20 years. This research aimed to isolate, characterize, and determine the biodiversity of potential probiotic yeasts obtained from Dadih. Isolation of probiotic yeast was done using Yeast Extract, Peptone, and Dextrose (YPD) media, followed by the identification of yeast using Sequence-Related Amplified Polymorphism (SRAP). Colonies relatedness was determined using the Numerical Taxonomy and Multivariate Analysis System (NTSYS). Two yeast isolates were further identified using Polymerase Chain Reaction (PCR) targeting the 18S rRNA gene. The probiotic characterization was done by determining pH resistance, bile salt resistance, proteolytic, lipolytic test, and hemolytic tests. Secondary metabolites were determined by conducting antioxidant, antidiabetic, antiinflammation, and antimicrobial tests. Interaction between secondary metabolites signals was determined by molecular docking using AutoDock software. Whole genome sequencing on Pichia kudriavzevii using Oxford Nanopore Technologies and genome annotation was performed using the Rapid Annotation using the Subsystem Technology (RAST) server. Fifty-five colonies were isolated, and their relatedness showed a minimum cutoff at a similarity level of 89% in the dendrogram. Two isolates, GBT 30 and GBT 37 were identified as Pichia occidentalis and Pichia kudriavzevii, respectively, based on the 18S rRNA sequence. Acid pH tolerance results showed both isolates survived at an acidic pH starting at pH 2 to pH 6. A bile salt resistance test showed that both isolates were able to show significant cell viability in 0.3 and 0.5% bile salt concentrations. Both isolates produced secondary metabolites, with GBT 30 showing good antimicrobial and antiinflammation properties than GBT 37. Whole-genome sequencing of P. kudriavzevii revealed a genome size of 10 906 850 bp, comprising five chromosomes with an average GC content of 38.26%, and secondary metabolites located on contig 7., Susu kerbau fermentasi yang biasa disebut Dadih mengandung sel ragi probiotik yang potensial. Ragi probiotik telah mendapatkan perhatian yang semakin besar dalam ilmu dasar dan klinis selama 20 tahun terakhir. Penelitian ini bertujuan untuk mengisolasi, mengkarakterisasi, dan mengetahui keanekaragaman hayati khamir probiotik potensial yang diperoleh dari Dadih. Isolasi ragi probiotik dilakukan menggunakan media Yeast Extract, Peptone, dan Dextrose (YPD), dilanjutkan dengan identifikasi ragi menggunakan Sequence-Related Aplified Polymorphism (SRAP). Keterkaitan koloni ditentukan dengan menggunakan Numerical Taxonomy and Multivariate Analysis System (NTSYS). Dua isolat khamir diidentifikasi lebih lanjut menggunakan Polymerase Chain Reaction (PCR) dengan sasaran gen 18S rRNA. Karakterisasi probiotik dilakukan dengan menentukan ketahanan pH, ketahanan garam empedu, proteolitik, uji lipolitik, dan uji hemolitik. Metabolit sekunder ditentukan dengan melakukan uji antioksidan, antidiabetes, antiinflamasi, dan antimikroba. Interaksi antara sinyal metabolit sekunder ditentukan dengan molekuler docking menggunakan perangkat lunak AutoDock. Pengurutan seluruh genom pada Pichia kudriavzevii menggunakan Oxford Nanopore Technologies dan anotasi genom dilakukan menggunakan Rapid Annotation menggunakan server Subsystem Technology (RAST). Lima puluh lima koloni diisolasi, dan keterkaitannya menunjukkan batas minimum pada tingkat kemiripan 89% pada dendrogram. Dua isolat, GBT 30 dan GBT 37 masing-masing diidentifikasi sebagai Pichia occidentalis dan Pichia kudriavzevii, berdasarkan urutan 18S rRNA. Hasil toleransi pH asam menunjukkan kedua isolat mampu bertahan pada pH asam mulai pH 2 hingga pH 6. Uji ketahanan terhadap
Keyword: probiotic, Whole Genome Sequencing, Pichia kudriavzevii, Pichia occidentalis, dadih, fermentation

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: 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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