Judul: Identification Yeast from Tempe Production Process based on Internal Transcribe Spacer Ribosomal DNA.
Abstrak: Tempe merupakan salah satu makanan tradisional khas Indonesia yang dibuat dari fermentasi kedelai dengan bantuan Rhizopus, terutama R. microsporus. Pada proses produksi tempe berbagai mikrob seperti bakteri asam laktat serta khamir dapat ditemukan. Adanya khamir pada proses produksi tempe di Indonesia telah dilaporkan sebelumnya, namun jenisnya belum diketahui. Oleh sebab itu, khamir pada proses produksi tempe perlu diidentifikasi. Khamir diidentifikasi dengan pendekatan filogenetik daerah ITS1-5.8S-ITS2 rDNA dan diperkuat dengan karakter morfologinya. Analisis filogenetik dilakukan dengan metode maximum parsimony pada perangkat lunak PAUP* 4.0b. Hasil identifikasi sebelas strain menunjukan bahwa dua strain termasuk strain khamir basidomiset (Kwoniella heveanensis dan Trichosporon asahii), tujuh strain khamir askomiset (Candida rugosa, Exophiala dermatitidis, Issatchenkia orientalis, Kodamaea ohmeri dan Saccharomyces cerevisiae), serta dua strain khamir lainnya diduga berkerabat dengan T. loubieri (basidiomiset) dan Lodderomyces elongisporus (askomiset). Sebanyak tujuh dari sembilan spesies khamir tersebut baru pertama kali dilaporkan keberadaannya pada tempe.
Keyword: Bogor Agricultural University, Institut Pertanian Bogor, IPB, ITS, Phylogenetic, Tempe, Yeast, Food microbiology, Persiapan sumber DNA, Ekstraksi DNA, Isolasi, Amplikasi DNA, Identifikasi molekus, Karakter morfologi

Judul: Analisis metagenom untuk pencirian komunitas bakteri dan fungi pada tempe
Abstrak: Tempe is an Indonesian traditional fermented food produced using Rhizopus as a starter culture. In practice, however, the starter culture as well as fermentation processes would involved a polymicrobial fermentation, which generated a unique tempe flavor and texture. This condition makes Indonesian tempe as one of the most complex fermented food, while at the same time would make it difficult to scale up tempe production with uniform quality and consistency. Because of complex microbial communities involved, cultureindependent methods or metagenomic analysis would be an essential tool to unravel this complex microbial fermentation. The aim of this study was to compare a number of tempe microbial communities based on Amplified Ribosomal Intergenic Sequence Analysis (ARISA). Fresh tempe samples were obtained from tempe producers in Java and Moluccas. 16S rRNA gene libraries and DNA sequencing were employed to analyze further the nature of microbial diversity in two selected tempe samples. The results of our study showed that different tempe producer possessed different Bacterial ARISA (BARISA) or fungi ARISA (FARISA) profiles. However, BARISA profiles were found to be more discriminative than FARISA, and therefore BARISA would be more useful for tempe genetic fingerprint or barcoding. Bacterial communities in two tempe samples (EMP and SDJD) were further investigated employing DNA sequence analysis of their 16S rRNA gene libraries. Sequences closely related to Klebsiella sp were found to be the majority among bacterial communities present in SDJD sample, while sequences closely related to Acetobacter sp. were found as predominant isolates in EMP samples. These significant differences in bacterial communities might reflect differences in tempe flavor or texture associated with their unique production or locality.
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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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