Judul: Optimasi Kondisi Produksi Enzim α-Amilase dari Bacillus licheniformis dengan Metode Fermentasi Padat pada Substrat Limbah Dedak Padi.
Abstrak: Enzim amilase merupakan kelompok enzim yang sangat dibutuhkan dalam bidang industri dan produksi komersialnya dari mikroorganisme mencapai 25%- 33% dari pasaran enzim di dunia. Tujuan penelitian ini mendapatkan kondisi optimum produksi α-amilase berdasarkan aktivitas ekstrak kasar enzim amilase dari bakteri Bacillus licheniformis dengan metode fermentasi substrat padat menggunakan limbah pertanian dedak padi. Optimasi dilakukan dengan berbagai parameter seperti waktu produksi (fermentasi), konsentrasi substrat, pH produksi, suhu fermentasi, dan ko-substrat. Pengukuran aktivitas amilase menggunakan metode DNS dan diukur absorbansinya menggunakan spektrofotometri pada panjang gelombang 540 nm. Produksi enzim α-amilase maksimum didapatkan pada waktu fermentasi selama 36 jam, dengan penambahan substrat dedak padi pada konsentrasi 50 g/L, pada kondisi pH 8, suhu 370C, maltosa sebagai kosubstrat dengan konsentrasi 1.5%.
Keyword: Amylase activity, Bacillus licheniformis, Optimization

Judul: Optimasi Kondisi Produksi Enzim Amilase dari Bakteri Laut Bacillus sp.
Abstrak: enzyme amylase. Microbial community is the largest marine biomass that enables many new sources producing enzyme. This study aimed to determine the optimum state of environmental conditions and nutrient media production of marine bacterium Bacillus sp. Various parameters such as substrate concentration, pH production, fermentation temperature, co-substrate, and nitrogen sources have been determined the optimal conditions. The method used is the spectrophotometric method. The maximum production of amylase enzyme obtained at a concentration of 1% starch substrate, pH 7, 30°C, maltose as co-substrate production, and casein as a nitrogen source with a value most optimum amylase enzyme activity, respectively for 2.547 U/mL, 2.109 U/mL, 2.414 U/mL, 2.675 U/mL, and the last 2.335 U/mL.
Keyword: Bogor Agricultural University (IPB), temperature., substrate, pH, optimization, nitrogen source, co-substrate, Bacillus sp., amylase activity

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology