Judul: Aktivitas Xilanase Beberapa Pleurotus ostreatus Menggunakan Substrat Pelepah dan Tandan Kosong Kelapa Sawit
Abstrak: Xylanase is a unique enzyme which could produced by bacteria and fungi. Xylanase has been known to have a various pH and temperature for its optimum activity, a reason why xylanase could be used in industries. Pleurotus ostreatus is a member of Fungi kingdom. In Indonesia, P. ostreatus known as jamur tiram. Jamur tiram is one of the favorite fungi to be cultured and probably produced xylanase. For many years, people are using sawdust for making fungi’s media culture, but there are a lot of agriculture and estate waste, for example palm oil’s frond and empty fruit bunch (EFB). This research was aimed for selection of P. ostreatus from many places which secreted xylanase by using palm oil’s frond and EFB as a substrat. Isolate BIOTROP and Gadog were fungi which produced xylanase and also celullase and lignolytic enzymes. After 30 days, weight media decrease between 9.17% until 40.69% from weight media before 30 days incubate. There was a different pH in palm oil’s frond and EFB media. The ratio of C : N showed change of carbon and nitrogen content before and after 30 days of incubation. The highest activity of xylanase enzyme was 0.584 IU/mL reached after 37 days of incubation. It was achieved from P. ostreatus Gadog strain using palm oil’s frond as a substrate. The highest protein concentrate was 35.6 mg/mL reached after 42 days of incubation. It was achieved from P.ostraetus Gadog strain using EFB as a substrate.
Keyword: Bogor Agricultural University (IPB), Xylanase., Pleurotus ostreatus, Palm Oil’s Frond, EFB

Judul: Karakteristik Proses Pembentukan dan Produk Xilanase dari Isolat Streptomyces sp. Terpilih Menggunakan Substrat Limbah Pertanian
Abstrak: Empty Fruit Bunch (EFB) and bagasse are lignocellulosic waste which rich of xylan. It has not been utilized optimally. Xylanase is alternative of xylan degrading agent. The aim of this research was to find and get the excellent of xylanase producing isolate and get some of the characters from the formation process and product of xylanase obtained on the fermentation of agricultural wastes substrate such as EFB and bagasse. The screening was done by comparing the xylanolytic index of six Streptomyces sp. isolates. Crude xylanase was analyzed by many parameters (incubation time, molecular weight, and type). Streptomyces sp. (P3CCA13) isolate was selected isolates with an xylanolitic index 0.818 (beechwood xylan), 0.500 (EFB) and 0.384 (bagasse). The highest xylanase activity on EFB, beechwood xylan and bagasse substrates are at incubation time 120 hours (7.5092 U/mL), 144 hours (5.9831 U/mL), and 192 hours (5.6660 U/mL). Based on TLC chromatogram of its products, this xylanase was predicted as endoxylanase (Rf=0.7143). The molecular weight of this xylanase was estimated between 16 to 47 kDa.
Keyword: bagasse, EFB, xylan, xylanase, Streptomyces sp. (P3CCA13)

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
Keyword: