Judul: Stabilitas Pigmen Fikosianin dari Spirulina platensis yang Dikultivasi Menggunakan Media Organik Berdasarkan Aktivitas Antioksidan dan Protein.
Abstrak: Fikosianin merupakan pigmen tertinggi dalam Spirulina platensis, namun tidak stabil terhadap suhu penyimpanan. Tujuan penelitian ini menentukan pengaruh jenis pelarut terhadap karakteristik fikosianin dan menentukan pengaruh penyimpanan terhadap stabilitas fikosianin. Tahapan penelitian ini meliputi: 1) kultivasi, pemanenan dan pengeringan biomassa S. platensis, 2) ekstraksi dan karakterisasi fikosianin, 3) pengeringan fikosianin, dan 4) penyimpanan fikosianin. Biomassa S. platensis diekstraksi menggunakan larutan akuades dan buffer fosfat untuk mendapatkan fikosianin. Hasil penelitian menunjukkan bahwa larutan buffer fosfat lebih efektif daripada akuades. Ekstraksi fikosianin menggunakan buffer fosfat menghasilkan fikosianin dengan 127,63±26,97 μg/mL protein, aktivitas antioksidan (IC50) 209,30±12,82 μg/mL, dan konsentrasi fikosianin yaitu 1,35±0,01 mg/mL. Fikosianin yang disimpan dalam suhu chilling (4 ℃) memiliki stabilitas tertinggi.
Keyword: Air, buffer fosfat, fikosianin, penyimpanan, S.platensis

Judul: Mikroenkapsulasi Fikosianin dari Spirulina platensis Menggunakan Variasi Rasio Kitosan Larut Air
Abstrak: Fikosianin merupakan pigmen dari Spirulina platensis (S. platensis) yang berperan sebagai penangkap cahaya serta berikatan dengan protein. Fikosianin memiliki beberapa kelemahan yaitu sangat sensitif terhadap suhu dan perubahan pH lingkungan sehingga mudah terdenaturasi. Stabilitas pigmen fikosianin dapat ditingkatkan dengan salah satunya teknologi mikroenkapsulasi. Mikroenkapsulasi fikosianin dapat meningkatkan stabilitasnya terhadap suhu dan perubahan pH lingkungan. Penelitian ini bertujuan untuk menentukan pengaruh rasio kitosan larut air terhadap karakteristik mikroenkapsulasi fikosianin dari S. platensis yang dikultur menggunakan media organik. Rendemen biomassa kering yang dihasilkan pada umur panen 14 hari adalah 0.14 ± 0.054 g/L. Konsentrasi, rendemen, dan antioksidan fikosianin secara berturut-turut adalah 1.26 ± 0.03 mg/mL, 31.62 ± 0.7 %, dan 641.54 ± 89.12 ppm. Derajat deasetilasi dan kelarutan kitosan larut air adalah 77.78 ± 0.98 % dan 82.45 ± 3.18 %. Hasil analisis ragam menunjukkan bahwa nilai warna, nilai IC50, dan kelarutan berbeda nyata (P<0.05).
Keyword: fikosianin, kitosan larut air, mikroenkapsulasi, Spirulina platensis

Judul: Quantitative Trait Loci Mapping for Trait in Categorical Scale
Abstrak: Genes or regions on chromosome underlying a quantitative trait are called Quantitative Trait Loci (QTL). Characterizing genes controlling quantitative trait on their position in chromosome and their effect on trait is through a process called QTL mapping. In estimating the QTL position and its effect, QTL mapping basically utilize the association between QTL and DNA markers. However, many important traits are obtained in categorical scale, such as resistance from certain disease. From a theoretical point of view, QTL mapping method assuming continuous trait could not be applied to categorical trait. This research was focusing on the assessment of the performance of Maximum Likelihood (ML) and Regression (REG) approach employed in QTL mapping as well as the performance of Lander and Botstein (LB) and Piepho method in determining critical value in testing the existence of QTL for binary and ordinal trait by means of simulation study. The simulation study to evaluate the performance of ML and REG approach was conducted by taking into account several factors that may affecting the performance of both approaches. The factors are: (1) marker density; (2) QTL effect; (3) sample size; (4) shape of phenotypic distribution; (5) number of categories; and (6) number of QTL. Moreover, the simulation study for evaluating LB and Piepho method in determining critical value was conducted by generating distribution of the test statistic under null hypothesis. From simulation study, it was obtained that LB and Piepho method showing similar performance in determining critical value in testing the existence of QTL for binary and ordinal trait. The simulation study also indicating that both methods could be used in determining critical value in QTL mapping analysis for binary trait as well as for ordinal trait if the REG approach is used but not if ML approach is used due to their poor performance. In assessing the performance of ML and REG approach in QTL mapping analysis for binary trait, the two approaches showing comparable performance; whereas for ordinal trait REG approach showing poor performance compared with ML approach in estimating thresholds. As a result, in QTL mapping analysis, ML and REG approach could be used when dealing with binary trait, whereas ML approach is suggested when dealing with ordinal trait.
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