Judul: Pengaruh Penghapusan Suatu Pengamatan Terhadap Struktur Ciri Matriks Data
Abstrak: Di dalam beberapa analisis peubah ganda, struktur ciri matriks data memainkan peranan yang penting. Struktur ciri ini dinyatakan dalam akar ciri dan vektor ciri. Ada kalanya, suatu pengamatan tertentu dapat sangat mempengaruhi stmktur ciri matriks datanya. Tulisan ini mempelajari pengaruh penghapnsan suatu pengamatan terhadap struktur ciri matriks datanya. Pengaruh penghapusan suatu pengamatan tersebut diperoleh dengan cara membandingkan struktur ciri matriks data lengkap dengan struktur ciri matriks data setelah pengamatan tersebut dihilangkan. Hasil yang diperoleh, yaitu bahwa penghapusan suatu pengamatan pada suatu subruang yang ortogonal terhadap suatu vektor ciri matriks data lengkap tidak akan mempengaruhi vektor ciri tersebut maupun akar ciri padanannya. Sedangkan penghapusan suatu titik pengamatan yang searah dengan suatu vektor ciri matriks data lengkap tidak mempengaruhi vektorvektor ciri lainnya beseria akar-akar ciri padanannya. Hanya akar ciri yang berpadanan dengan vektor ciri yang searah tadi yang terpengaruh. Bila akar-akar ciri matriks data lengkap diurutkan, maka setelah penghapusan urutan tersebut dapat saja berubah. Di samping itu juga diperoleh bahwa banyaknya akar ciri bemilai not pada matriks data lengkap adalah kurang dari atau sama dengan banyaknya akar ciri bemilai nol pada matriks data setelah penghapusan.
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Judul: Pemeriksaan suatu matriks data dengan metode biplot
Abstrak: Biplot adalah salah satu metode untuk menyajikan data secara visual. Dengan metode ini dapat diperiksa hubungan antar individu dan hubungan antar peubah. Metode ini dapat pula menerangkan posisi relatif individu amatan terhadap peubah. Disebut biplot karena terdiri atas plot dua jenis vektor. Unsur-unsur matriks data didekati oleh perkalian skalar kedua jenis vektor ini. Sifat-sifat data dalam biplot berkaitan dengan nilai yang digunakan. Nilai = 0 membuat ragam, peragam dan korelasi antar peubah diwakili oleh vektor-vektor pengaruh lajur. Jarak Mahalanobis antar individu amatan diwakili oleh jarak antar vektor-vektor pengaruh baris. Nilai x =1 memberikan plot skor komponen utama pertama dan kedua, Jarak antar vektor-vektor pengaruh baris mewakili jarak Euclideus antar individu amatan. (2) Biplot data yang diperiksa memiliki 2 0.9886. Peubah pertama berkorelasi negatif dengan peubah lain, dan cukup erat. Peubah kedua dan keempat serta peubah kelima dan ketujuh sangat erat korelasinya. Keragaman terbesar dimiliki oleh peubah pertama. Individu kesembilan memiliki nilai-nilai yang ekstrem. Pada peubah pertama nilainya sangat jauh di bawah rata-rata tetapi pada peubah lainnya leb lebih besar dari rataannya…
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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