Judul: Game Coloring Number Suatu Graf
Abstrak: Pewarnaan pada graf terdiri atas tiga macam pewarnaan yaitu pewarnaan simpul, pewamaan sisi, dan pewarnaan bidang. Coloring game merupakan salah satu permainan pewarnaan simpul yang dilakukan oleh dua orang pemain. Game chromatic number dan game coloring number merupakan nilai yang dapat dicari dari permainan coloring game. Dalam penelitian ini dibuktikan tiga teorema. Pertama, jika terdapat graf sembarang maka nilai game coloring number graf tersebut lebih besar atau sama dengan nilai game chromatic number-nya. Kedua, untuk sembarang graf dengan dua subgraf, nilai game coloring number graf kurang dari atau sama dengan nilai game coloring number subgraf pertama ditambah dengan nilai maximum degree subgraf kedua. Ketiga, untuk sembarang graf yang memiliki subgraf, nilai game coloring number subgraf kurang dari atau sama dengan nilai dari game coloring number graf tersebut.
Keyword: Coloring, Coloring game, Game chromatic number, Game coloring number, Graph theory, Teori graf, Permainan graf, Teorema

Judul: Coloring Covid-19 Map Based on Fuzzy Directed Graph
Abstrak: Pewarnaan graf merupakan salah satu aplikasi dalam teori graf dengan mewarnai verteks suatu graf dimana verteks yang adjacent diberi warna yang berbeda. Salah satu aplikasi pewarnaan graf adalah pewarnaan peta. Pada karya ilmiah ini dibahas pewarnaan peta kasus COVID-19 di Indonesia menggunakan graf berarah fuzzy. Tiap provinsi bertindak sebagai verteks dan sisi berarah yang terhubung antara dua verteks ada jika terdapat riwayat perjalanan antara satu provinsi ke provinsi lain. Pewarnaan graf berarah fuzzy mengikuti algoritma Mahapatra. Dari kajian ini ditunjukkan bahwa indeks kromatik dari hasil pewarnaan graf berarah fuzzy pada kasus COVID-19 di Indonesia terdiri dari dua warna dasar minimum yang dibutuhkan graf setelah seluruh verteks diwarnai dengan nilai minimum 1,463., Graph coloring is one of the applications in graph theory by coloring the vertices of a graph where adjacent vertices are given different colors. One of the applications of graph coloring is map coloring. In this manuscript, the coloring of maps of COVID-19 cases in Indonesia using directed fuzzy graphs. Each province acts as a vertex and there exists a directed edge connected between two vertices if there is a history of travel between one province to another. The coloring of the directed fuzzy graph is based on Mahapatra's algorithm. This study shows that the chromatic index of the directed fuzzy graph coloring result in the case of COVID-19 in Indonesia consists of two minimum base colors required by the graph after all vertices are colored and the minimum value is 1,463.
Keyword: chromatic number, directed fuzzy graph, graph coloring, map coloring

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