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: Aktivitas Selulolitik beberapa Kapang
Abstrak: Cellulose is the main component of cell wall of plants and it is the most abundant biopolymer on earth. Generally, cellulose is degraded by microorganisms-producing cellulase. The enzyme consists of endoglucanase, exoglucanase, and cellobiase. The aim of this research was to study the cellulolytic’s ability of some molds. Fourty two fungal isolates were first examined of their cellulolytic’s ability on CMC agar. T. reesei QM6a was used as comparison strain. Certain isolate of Aspergillus niger, Aspergillus ornatus, and Paecilomyces sp. have cellulolytic index that were higher than those of other isolates. The optimum activity for CMC-ase of A. niger and A. ornatus occurred on 3 days incubation, while those of Paecilomyces sp. and T. reesei QM6a was 5 days and 2 days incubation, respectively. Of those species, A ornatus showed the highest activity of CMC-ase (0.550 nkat/ml), avisel-ase (0.077 nkat/ml), and FP-ase (0.255 nkat/ml). The optimum temperature for CMC-ase activity of A. ornatus was 30 0C, while the optimum acidity was 7.
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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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