Judul: Sifat Fisis, Warna dan Mekanis Lima Jenis Kayu Akibat Pemaparan Alami
Abstrak: Sifat fisis dan mekanis, serta warna kayu dapat berubah karena dipengaruhi oleh cuaca dan keadaan sekitarnya. Tujuan dari penelitian ini untuk mengetahui ketahanan alami kayu sengon, meranti, mahoni, jati dan merbau terhadap pemaparan cuaca terkait perubahan warna dan sifat fisis dan mekanis. Pemaparan cuaca dilakukan selama sepuluh bulan dengan sudut pemaparan 45⁰ menghadap selatan terhadap total 35 sampel kayu. Sifat fisis mencakup perubahan kadar air, kerapatan, berat, dan kecerahan warna kayu. Sifat mekanis yang diuji berupa dugaan penurunan modulus elastisitas dinamis. Hasil penelitian sifat fisis menunjukan kadar air, kerapatan, berat, dan kecerahan warna kayu yang diberikan perlakuan pemaparan cuaca alami mengalami penurunan. Begitu pula dengan sifat mekanis modulus elastisitas kayu mengalami penurunan secara signifikan setelah 10 bulan pemaparan.
Keyword: perubahan warna, sengon, meranti, mahoni, jati, merbau, pemaparan cuaca

Judul: Pengaruh Pemaparan Alami terhadap Sifat Fisis dan Mekanis Berbagai Jenis Sambungan Kayu
Abstrak: Perubahan sifat fisis dan mekanis kayu atau produk kayu yang diaplikasikan di luar ruangan disebabkan oleh berbagai faktor. Sinar ultraviolet dan kelembapan merupakan agen utama penyebab kerusakan pada kayu. Sambungan pada produk kayu juga penyebab turunnya sifat fisis dan mekanis pada kayu. Tujuan penelitian ini adalah menentukan perubahan sifat fisis dan mekanis yang terjadi pada berbagai jenis sambungan kayu meranti (Shorea spp.) dan keruing (Dipterocarpus spp.) akibat pemaparan alami selama 210 hari. Papan kayu meranti dan keruing dipotong dan dibentuk menjadi non joint (kontrol), butt joint, scarf joint, dado joint dan finger joint. Contoh uji diletakkan pada rak pemaparan selama 210 hari. Selama masa pemaparan, dilakukan pengujian sifat fisis setiap 15 hari dan sifat mekanis setiap 30 hari. Hasil penelitian ini menunjukkan sifat fisis dan mekanis dari sambungan kayu menurun selama pemaparan 210 hari. Finger joint meranti merupakan jenis sambungan yang paling tahan terhadap penurunan sifat fisis dan mekanis akibat pemaparan.
Keyword: butt joint, dado joint, finger joint, scarf joint, weathering

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