Judul: Penapisan Bakteri Asosiatif Karang Lunak (Octocorallia; Alcyonacea) Sinularia dura dan Lobophytum strictum yang Potensial sebagai Alternatif Penanganan Microfouling di Laut.
Abstrak: Microfouling (pembentukan biofilm) merupakan syarat utama terjadinya biofouling, sehingga untuk melakukan penghambatan terjadinya biofouling pada struktur bangunan laut dapat dilakukan dengan menghambat terjadinya biofilm. Beberapa mikroorganisme laut seperti bakteri yang berasosiasi dengan karang lunak mampu menghasilkan sejumlah metabolit sekunder yang dapat menghambat pertumbuhan biofilm. Tujuan dari penelitian ini adalah mencari bakteri asosiasi potensial dari karang lunak Sinularia dura dan Lobophytum strictum yang dapat menghasilkan senyawa bioaktif sebagai sumber anti-microfouling alami. Penelitian ini dilakukan pada bulan Mei hingga Agustus 2011. Penelitian dibagi menjadi beberapa tahap, yaitu pengambilan sampel karang lunak jenis Sinularia dura dan Lobophytum strictum, penjebakan biofilm bakteri, isolasi bakteri, dan uji antagonisme. Pengambilan sampel karang lunak dan penjebakan biofilm bakteri dilakukan pada waktu dan tempat yang sama yaitu di perairan Barat pulau Pramuka, Kepulauan Seribu. Uji antagonisme dilakukan antara bakteri asosiasi karang lunak terhadap bakteri pembentuk biofilm dengan metode difusi agar. Parameter kualitas perairan (fisika-kimia) yang diukur sebagai data penunjang meliputi suhu, kadar garam, kecerahan, pH, nitrat, fosfat, TSS, dan COD. Hasil penelitian menunjukkan bahwa sebanyak 24 isolat bakteri asosiasi berhasil diisolasi dari karang lunak jenis Sinularia dura dan Lobophytum strictum. Uji antagonisme menunjukkan sebanyak 23 isolat (95,83%) bakteri asosiasi mampu menghambat pertumbuhan bakteri pembentuk biofilm. SD6 dan LS1 merupakan isolat bakteri yang memiliki tingkat aktivitas penghambatan paling tinggi terhadap bakteri pembentuk biofilm. Bakteri SD6 dan LS1 tersebut berpotensi sebagai sumber anti-microfouling alami yang ramah lingkungan.
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Judul: Isolasi dan Potensi Antagonistik Bakteri Asosiatif Karang dari Genus Acopora di Perairan Blitar, Jawa Timur
Abstrak: Ekosistem terumbu karang memiliki kerentanan tinggi terhadap perubahan lingkungan yang dapat mengakibatkan terjadinya pemutihan karang. Peristiwa pemutihan karang menyebabkan terjadinya perubahan pada komunitas mikroba (holobiont) karang. Bakteri yang berasosiasi dengan karang memiliki mekanisme pertahanan diri terhadap mikroorganisme yang berpotensi mengganggu inang karang. Potensi antagonistik terbentuk dari adanya aktivitas antagonisme bakteri. Penelitian ini dilakukan terhadap sampel karang Acropora sehat dan yang mengalami pemutihan dari perairan Blitar, Jawa Timur. Isolasi bakteri dilakukan dengan menggunakan metode cawan sebar yang kemudian koloninya dimurnikan dengan metode gores kuadran. Isolat tersebut kemudian ditinjau kemampuan aktivitas antagonisnya menggunakan metode double layer. Didapatkan total 6 sampel karang didapatkan 31 isolat didominasi oleh bentuk morfologi tepian licin, bentuk bundar, elevasi cembung, dan tidak berpigmen (krem) yang merupakan bakteri Gram negatif dengan bentuk coccus. Hasil uji aktivitas antagonis menunjukkan 14 isolat karang sehat yang dapat menghambat 8 isolat karang yang mengalami pemutihan dengan bakteri AcD.14 menjadi bakteri yang paling banyak direspon. Aktivitas hambat yang ditunjukkan hasil uji antagonis sangat bervariasi mulai dari aktivitas lemah hingga aktivitas sangat kuat dengan rata-rata hasil uji memiliki aktivitas kuat dengan luas zona hambat berada pada rentang 11.52±0.12 mm to 19.78±0.13 mm. Sehingga penelitian ini membuktikan adanya potensi bakteri asosiasi karang dalam menghambat potensi patogen karang., Coral reefs ecosystem have high vulnerability to environtmental changes that cause coral bleaching. Coral bleaching events can change coral microbial communities (holobiont). Coral-associated bacteria are known to have self-defense mechanism against microorganisms that have the potential to disrupt coral hosts. Antagonistic potential bacteria is formed when bacteria tested show antagonistic activity. This research was conducted on healthy and bleached corals of Acropora from Blitar waters, East Java. Isolation of coral bacteria was carried out using spread plate method, and later purified using streak plate method. These isolates are evaluated for their antagonistic activity using double layer method. A total of 6 coral samples were obtained, 31 isolates were found which are dominated by morphological forms of smooth edges, round shapes, convex elevations, and not pigmented (beige), which are gram-negative bacteria with coccus shape. The results of the antagonist activity test showed 14 isolates from healthy coral samples could inhibit 8 isolates from bleached coral samples with AcD.14 being the most responsive bacteria. The inhibitory activity shown varied from weak to very strong activity with the average having strong activity with inhibition zone area range from 11.52 ± 0.12 mm to 19.78 ± 0.13 mm. This research proves the potential of coral assosiated bacteria in inhibiting potential coral pathogens.
Keyword: Acropora, aktivitas antagonis, bakteri asosiasi, pemutihan karang

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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