Judul: Aktivitas Selulolitik dan Karakterisasi Aktinomiset Asal Tanah Gambut
Abstrak: In the peat soil, various groups of microorganism decomposing peat are present, including actinomycetes. Eighty isolates of actinomycetes were isolated from peat soil samples. Congo red clearing zone assay was used for qualitative observation of cellulolytic activity and it was found that 20 isolates showed positive results with clear zone around the colony. Cellulase production was assayed by measuring the amount of glucose liberated in μmol mL-1 min-1 by using the dinitrosalicylic acid assay method. Among the twenty isolates, the isolates 15 and 42 were found to have relatively higher cellulase enzyme activity both qualitatively and quantitatively compared with the others. Maximum production of cellulase by isolate 15 and 42 were detected on day-30 and day-15, respectively, and showed CMCase, Avicel, and FPase activities which indicated a synergy of endoglucanase and exoglucanase in the cellulase enzyme system of the tested isolates. Furthermore, morphological characteristics of 15 and 42 isolates were compared to other reference strains, belongs to Streptomyces species. The analysis of nucleotida of 16S rRNA showed that isolate 15 were closely related to the Streptomyces diastaticus with maximum identity 98% and isolate 42 were closely related to the Streptomyces exfoliatus with maximum identity 94%. Meanwhile phylogenetic analysis showed that isolate 15 homologous to isolate 42 with a bootstrap value of 100%. This study provided important basic information on potential cellulolytic from actinomycetes group.
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Judul: Identifikasi Bakteri Selulolitik Asal Tanah Situ Gede dengan Teknik Genetika Molekuler.
Abstrak: Cellulose is a biopolymer in nature which is dominant agricultural waste. Many practices degrade cellulose into glucose molecules by using cellulase enzyme. This research aim to identify the cellulolytic bacteria and to test cellulase activities. The methods are platting isolates, halo zone testing, DNA isolation, visualization of DNA fragmen by electrophoresis, 16S rDNA gene amplification by Polymerase Chain Reaction (PCR), 16S rDNA gene divesity analysis with restriction enzymes, DNA sequensing analysis, and enzymatic assay using CMC selective media. Six isolates were analyzed by restriction enzyme and showed three diversity of based, its differences by size. The size of the bases are 1500 bp, 850 bp, and <850 bp. Sequensing DNA by GeneBank in NCBI web are 85% indentical between Cellvibrio fibrivorans to isolate D714 and then 81% identical to Cellvibrio gandavensis to isolate J531. Enzyme activities of isolates D714, D533, J731, and J531 has been tested enzyme to get the highest activity on seventh day is 0.1054 IU/mL, 0.0996 IU/mL, 0.101 IU/mL, and 0.9689 IU/mL.
Keyword: cellulolytic bacteria, cellulase enzyme, gene 16S rDNA

Judul: Pemodelan Nilai Tukar Rupiah Terhadap US Dollar Menggunakan Deret  Waktu Hidden Markov Dua Waktu Sebelumnya
Abstrak: Nilai tukar Rupiah terhadap US Dollar mengalami perubahan setiap waktunya dalam periode yang panjang dan perubahan yang terjadi mungkin terjadi kembali di masa mendatang. Jika penyebab kejadiannya tidak diamati secara langsung dan membentuk suatu rantai Markov maka perubahan nilai tukar Rupiah dapat dimodelkan dengan model deret waktu hidden Markov. Untuk menggambarkan perilaku nilai tukar Rupiah terhadap US Dollar, dalam karya ilmiah ini digunakan model deret waktu hidden Markov dua waktu sebelumnya. Model ini mengasumsikan bahwa nilai tukar Rupiah terhadap US Dollar bergantung pada rantai Markov yang merupakan penyebab kejadian yang tidak diamati dan nilai tukar Rupiah dua waktu sebelumnya.
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