Judul: Perbandingan Unit Contoh Lingkaran dan Unit Contoh N-Jumlah Pohon dalam Pendugaan Simpanan Karbon
Abstrak: Penerapan metode penarikan contoh dalam kegiatan inventarisasi hutan pada umumnya menggunakan unit contoh lingkaran, terutama pada tegakan muda hutan tanaman. Selain unit contoh lingkaran, sebenarnya telah diketahui unit contoh berupa n-jumlah pohon untuk pendugaan volume tegakan pada hutan tanaman. Penelitian ini bertujuan membandingkan hasil pendugaan simpanan karbon terhadap unit contoh lingkaran dan unit contoh n-jumlah pohon. Penelitian dilakukan dengan 82 unit tegakan pinus dan agathis berumur 1–5 tahun di areal rehabilitasi TOSO, Hutan Pendidikan Gunung Walat, Sukabumi. Unit contoh 4, 5, dan 6-jumlah pohon ditempatkan pada titik pusat unit contoh lingkaran. Pengukuran dilakukan untuk mendapatkan data diameter dan jarak pohon dari titik pusat. Hasil penelitian menunjukkan unit contoh lingkaran memiliki nilai kesalahan penarikan contoh terkecil dibandingkan unit contoh 4, 5, dan 6-jumlah pohon dalam menduga nilai simpanan karbon sebesar 26.32%. Dengan demikian, unit contoh n-jumlah pohon belum dapat menjadi alternatif unit contoh dalam pendugaan simpanan karbon di areal rehabilitasi TOSO.
Keyword: penarikan contoh sistematik, unit contoh lingkaran, unit contoh n-jumlah pohon, simpanan karbon, tegakan muda

Judul: Perbandingan Bentuk Unit Contoh pada Penerapan Sampling dalam Pendugaan Potensi Tegakan Akasia
Abstrak: Bentuk unit contoh dalam inventarisasi hutan yang diterapkan Perum Perhutani menggunakan bentuk unit contoh lingkaran. Selain bentuk unit contoh lingkaran terdapat juga bentuk unit contoh jumlah pohon yang dapat diterapkan di hutan tanaman. Penelitian ini bertujuan membandingkan tingkat ketelitian dan efisiensi berbagai bentuk unit contoh pada penerapan sampling tegakan akasia di RPH Maribaya BKPH Parung Panjang KPH Bogor. Sebanyak 44 unit contoh berupa lingkaran berukuran 0.02 ha, 0.04 ha, dan 0.1 ha serta jumlah pohon sebanyak 5, 6, 7, 8, 9, dan 10 dipilih secara acak pada setiap kelas umur dengan metode stratified sampling. Perbandingan terhadap hasil pendugaan parameter tegakan yang meliputi kerapatan, luas bidang dasar, dan volume pada setiap unit contoh untuk menentukan bentuk unit contoh yang teliti dan efisien. Hasil penelitian menunjukkan bahwa unit contoh lingkaran 0.02 ha memiliki tingkat ketelitian terbaik dan efisiensi relatif tertinggi pada pendugaan tegakan akasia.
Keyword: metode stratified sampling, tingkat ketelitian dan efisiensi, unit contoh jumlah pohon, unit contoh lingkaran

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