Judul: Seleksi Isolat Bakteri Indigenous Penghasil Selulase dan Karakterisasi Enzim untuk Wood Chips Pretreatment
Abstrak: Selulase adalah kelompok enzim hidrolase termasuk endoglukanase, exoglukanase dan β-glukosidase yang memutuskan ikatan glikosidik β-1,4 di dalam selulosa, sedodekstrin, selobiosa, dan turunan selulosa lainnya. Tujuan peneliatian ini adalah menentukan isolat paling potensial sebagai penghasil selulase dan menentukan karakter enzim yang diproduksi oleh isolat paling potensial. Isolat yang diseleksi dalam penelitian ini terdiri atas tujuh isolat bakteri. Uji aktivitas selulase menunjukkan bahwa isolat RA-1 dengan indeks selulolitik paling besar (3.314) memiliki aktivitas paling tinggi diantara isolat lainnya dengan nilai 1.367 U/mL. Aktivitas tertinggi diperoleh pada pH 7 dan suhu inkubasi 60 οC. Elektroforegram zimogram menunjukkan bahwa bobot molekul enzim diperkirakan 52.480 kDa (RA-1 dan RCc) dan 40.498 kDa (B.RK-2). Ion logam Ca2+, K+, Zn2+, Mg2+ dan Fe2+ berperan sebagai inhibitor enzim yang dihasilkan oleh isolat RA-1 sedangkan ion logam Mn2+ berperan sebagai aktivator.
Keyword: enzim, hidrolase, selulase, selulolitik, zimogram

Judul: Karakterisasi Enzim Selulase dari Isolat Bakteri Selulolitik Asal Tanah
Abstrak: Peningkatan produk pertanian diikuti pula oleh meningkatnya limbah hasil pertanian. Limbah pertanian yang dihasilkan dapat didegradasi menjadi bahan yang lebih bermanfaat dengan menggunakan mikroorganisme, contohnya bakteri. Isolat bakteri SL 03 asal tanah lembab di sekitar kawasan kampus Institut Pertanian Bogor (IPB) memiliki kandungan selulase yang mampu untuk mendegradasi selulosa menjadi molekul yang lebih sederhana. Penelitian ini bertujuan untuk mengkarakterisasi isolat SL 03 yang meliputi pH optimum, suhu optimum, serta substrat yang sesuai. Pengukuran aktivitas enzim selulase ekstrak kasar dilakukan pada jam produksi enzim selulase tertinggi dengan modifikasi metode 3.5-dinitrosalicylic acid (DNS) pada substrat CMC, Avicel dan kertas saring. Produksi optimum enzim ekstrak kasar didapat pada jam ke-6 yaitu sebesar 0,004 U/mL. Selulase dari isolat SL 03 memiliki aktivitas tertinggi pada pH 5 dan suhu 80oC. Selulase dari bakteri isolat SL 03 memiliki kemampuan tertinggi mendegradasi substrat Avicel.
Keyword: bakteri selulolitik, karakterisasi, limbah pertanian, selulase

Judul: The Effects of Variance of Interest rate to Variance of Annuity Future Values
Abstrak: Time value of money is a concept that refers to the difference of the value of money due to time difference. The value of money for present time would not be the same as the value of money in the future. The value of money for present time is called as Present Value (PV) of the money and the value of money for future time is called Future Value (FV) of the money. Determination the value of money, for present and future time, depends on the time and rate of return. The value of money is determined by several factors such as inflation, fluctuation of interest rates, and government policy in securities and taxation. Due to fluctuation of the value of money we need a FV formulation, it is useful for knowing whether an investment can be profitable or not, and this information is useful also in budget analysis. Annuity is defined as a series of payments made for a specific period. The payment, fixed or varied, can be made at the beginning or at the end of the period. Annuity paid at the beginning of the period is called annuity-due and annuity paid at the end of the period is called immediate annuity-certain. The accumulated value of the annuity after few years later is called as a final value or a future value. Burnecki et al. (2003) have discussed about the FV of a fixed-rate annuity in which payments are made according to the arithmetic or geometric series. They have also examined FV for annuities in which payments are made according to arithmetic or geometric series with random rates of interest. This paper examines FV for annuity-due in which payments are made according to arithmetic or geometric series with interest rates as a random variable, which is normal distribution ,  . Future value formula is expressed in recursive form. FV for annuity-due which payments are made according to the arithmetic or geometric series with random rates of interest is calculated by theoretical way and simulation way. The random rates of interest is denoted as k k i  i  , where k i an independent random variable; i is a constant and k  is a random variable which has normal distribution ,  . By using the determined parameters, a sequence of random rates of interest are generated for theoretical calculation. Meanwhile for the simulation, the random rates of interest is generated 1000 times for the simulation. The generated data give mean value, variance, and standard deviation. Moreover, error of mean value, variance, and standard deviation from the theoretical and simulation results are calculated. Error calculation uses Symmetric Mean Absolute Percentage Error (SMAPE). The smaller the value of SMAPE is the more accurate the simulation. The interest rate variances are varied from 0.000036 to 0.0001 to study the relationship between variance of rates of interest and variance of future value. The theoretical and simulation results show that when the variance of random rates of interest increases, then the variance of FV increases linearly. FV of the annuity-due in
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