Judul: Pelabelan Otomatis Citra Menggunakan Fuzzy C Means untuk Sistem Temu Kembali Citra
Abstrak: Pelabelan citra secara manual memiliki kelemahan karena memerlukan waktu yang banyak dan sangat tergantung pada subjektifitas pengguna dalam mendeskripsikan citra. Oleh karena itu diperlukan pelabelan citra secara otomatis berdasarkan isi citra. Penelitian ini menggunakan Fuzzy C-Means untuk mengelompokkan informasi warna dan tekstur ke dalam beberapa region berdasarkan objek citra. Dari pengelompokkan ini diperoleh kamus kata untuk setiap citra. Dengan adanya kamus kata tersebut diharapkan dapat mempercepat proses temu kembali. Hasil penelitian menunjukkan bahwa nilai presisi temu kembali citra berdasarkan proses pelabelan ini mencapai 86.68 %.
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Judul: Metode Support Vector Machine untuk Klasifikasi pada Sistem Temu Kembali Citra
Abstrak: Citra memiliki bentuk, tekstur dan warna yang sangat beragam. Hal ini menyebabkan sulitnya dilakukan pencarian citra. Klasifikasi citra merupakan salah satu tahap yang paling penting pada temu kembali berbasis citra. Penelitian ini mengimplementasikan metode Support Vector Machine (SVM) dengan algoritma optimisasi Sequential Minimal Optimization (SMO) untuk tahap klasifikasi pada sistem temu kembali citra berdasarkan ciri warna. Penelitian juga membandingkan kinerja SVM dengan pendekatan jarak Euclidean pada sistem temu kembali citra. Data yang digunakan diambil dari basis data Caltech dan www.flowers.vg sebanyak 300 citra untuk berbagai macam objek. Format citra adalah JPEG berukuran 50×50 piksel. Seluruh citra di dalam basis data disegmentasi menggunakan algoritma Expectation-Maximization (EM) dan diekstraksi menggunakan metode Fuzzy Color Histogram (FCH) untuk membentuk indeks warna citra di dalam basis data. Kemudian indeks warna citra ini dilatih menggunakan algoritma optimisasi SMO untuk membentuk model klasifikasi SVM. Model klasifikasi ini digunakan untuk mengklasifikasikan citra. Dari hasil klasifikasi, diambil citra di dalam basis data yang memiliki kelas yang sama dengan citra kueri dan citra dari kelas lain yang memiliki tingkat kemiripan yang tinggi dengan citra kueri sebagai citra hasil temu kembali. Evaluasi terhadap hasil temu kembali dilakukan menggunakan rataan precision untuk setiap tingkat recall. Berdasarkan penelitian ini, temu kembali citra menggunakan metode klasifikasi SVM memiliki hasil temu kembali dengan rataan precision mencapai 76.76%, sedangkan pada temu kembali citra yang hanya berdasarkan jarak Euclidean antar citra memiliki rataan precision 50.91%.
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Judul: Extracellular Expression of thermostable Geobacillus stearothermophilus T1.2RQ Lipase for Biodiesel Production
Abstrak: The extracellular expression of enzymes in an excellent secretion host such as Bacillus subtilis is a useful strategy for making enzymes of industrial significance more affordable by lowering the cost of its downstream processing. Lipases are a category of hydrolases that catalyze the hydrolysis of triglycerides to glycerol and free fatty acids. Also, lipases catalyze the hydrolysis and transesterification of other esters as well as the synthesis of esters. They can perform very specific biotransformation reactions and are widely used in food, organic synthesis, detergents, cosmetic, and pharmaceutical industries. Geobacillus stearothermophilus T1.2RQ lipase is an industrially-desired thermostable lipolytic enzyme with an excellent hydrolytic and transesterification activity. This study aimed to express T1.2RQ lipase, in B. subtilis WB800 and ensure its secretion into the extracellular medium. Three signal peptides (AmyQ, Epr, LipA) and two promoters (Pgrac01 and Pgrac100) were used in the secretory-expression of T1.2RQ lipase, based on five constructed expression vectors constructed by restriction cloning and PCR mutagenesis. Sangers sequencing was used to verify constructs to ensure they are in the correct reading frame. Recombinants vectors, pHT43 (plasmid control), pHT43-T1.2RQ, pHT43- T1.2RQ_AmyQ, pHT43-T1.2RQ_Epr, and pHT43-T1.2RQ_LipA, were transformed by electroporation into Bacillus subtilis WB800. The electroporation was successful with the optimum condition of 2500V, 200 ohms, 25µF, and 5milliseconds. Recombinant B. subtilis pHT43 (negative control) and pHT43-T1.2RQlip + signal peptides were streaked on the lipidic agar, LA+TBN. All four recombinants, including the negative control (B. subtilis WB800-pHT43), produced clear zones on the TBN agar plate after overnight incubation (fig 2), indicating the presence of a lipolytic enzyme in all of the recombinant B. subtilis cells. pHT43-T1.2RQlip + signal peptides (AmyQ, Epr, and LipA) have clear zones with significantly higher diameters than B. subtilis WB800-pHT43 (negative control). This phenomenon suggests that the recombinant thermostable lipase T1.2RQ introduced into these cells was successfully expressed, thereby increasing the lipolytic capability of its host cells T1.2RQ lipase was expressed in 50ml terrific broth medium (TB) and the expression induced with 1mM IPTG. Lipase activity assay using p-nitrophenyl esters showed that all three signal peptides directed the secretion of T1.2RQ lipase into the extracellular medium. Signal peptide, LipA, resulted in the highest extracellular activity of 5.6 U/mL, which corresponds to a 6-fold increase over the parent B. subtilis WB800 strain. Meanwhile, signal peptides, AmyQ and Epr produced 4.2 U/mL and 3.4 U/mL activity respectively. SDS-Zymogram analysis confirmed that T1.2RQ lipase was correctly processed and secreted in its original size of 44 kDa. An attempt to further increase lipase expression level by promoter optimization showed that, contrary to expectation, promoter Pgrac100 exhibited similar expression levels as the original Pgrac01. Nevertheless, the demonstration of the successful secretion of T1.2RQ lipase in this work confirms the latter as a promising approach for the industrial production of the enzyme
Keyword: Bacillus subtilis, Expression, Extracellular, Heterologous, Lipase, Thermostable