Judul: Antibacterial Activity from Enzymatic Hydrolysis of Goat’s Milk Whey.
Abstrak: Penggunaan bahan tambahan pangan berupa bahan kimia untuk mencegah dan menghambat pertumbuhan mikoorganisme dan memperpanjang umur simpan memiliki dampak lain terhadap keamanan penggunaanya terutama munculnya resistensi mikroorganisme terhadap antimikroba sintetik. Hal ini mendorong pengembangan antimikroba yang berasal dari bahan alami salah satunya yang berasal dari bahan pangan hewani yaitu susu. Komponen bioaktif protein susu tidak selalu ada dalam keadaan alamiahnya diantaranya dapat berupa prekursor atau peptida yang hanya akan aktif apabila telah dihidrolisis secara in vitro dari protein alamiahnya. Hidrolisis terhadap protein susu dapat dilakukan menggunakan enzimenzim proteolitik dari berbagai sumber, diantaranya adalah enzim yang berasal dari Bacillus lincheniformis. Penelitian ini menggunakan konsentrasi enzim Bacillus lincheniformis yang berbeda (0,5%, 1% dan 1,5%) untuk menghasilkan hirdolisat yang memiliki aktivitas antibakteri dilihat dari nilai kadar protein, profil SDS PAGE dan besarnya zona hambat (metode cakram). Proses hidrolisis menghasilkan kadar protein sebesar 0,027-0,049 mg/mL dengan aktivitas antibakteri sebesar 8,8 mm untuk Escherichia coli pada whey yang dihidrolisis dengan enzim taraf 1,5 %dan 8,7mm untuk Staphylococcus aureus pada whey yang dihidrolisis dengan enzim taraf 1 %. Hasil dari hidrolisis juga menghasilkan peptida dengan berat molekul < 5 kDa., Food additives had been used to prevent and inhibit the growth of microorganisms and extend shelf life of food. Based on the safety of their used, it has an impact such as microorganism resistance to synthetic antimicrobials. This encourages the development of antimicrobials derived from natural ingredients, especially from milk. The bioactive components of milk protein have not always existed in their natural state, including precursors or peptidas that will only be active if they have been hydrolyzed in vitro from their natural proteins. Hydrolysis of milk protein can be carried out using proteolytic enzymes from various sources, including enzymes from Bacillus lincheniformis. This study used in different concentrations of the enzyme Bacillus lincheniformis (0.5%, 1% and 1.5%) to produce hydrolyzate which has antibacterial activity in terms of protein content, SDS PAGE profile and the size of the inhibition zone (disc method). The hydrolysis process resulted in a protein content of 0.027- 0.049 mg/mL with an antibacterial activity of 8.8mm in Escherichia coli in whey hydrolyzed with enzyme level 1.5% and 8.7 mm for Staphylococcus aureus in whey hydrolyzed with enzyme level 1 %. The result of hydrolysis also produces protein with a molecular weight of < 5 kDa.
Keyword: antibakteri, protease Bacillus lincheniformis, hidrolisis, susu kambing

Judul: Protein dan Peptida Susu Kambing serta Potensinya sebagai Antibakteri
Abstrak: Bioactive peptides are specific protein fragments derived from hydrolysis that has positive effect on human health. Caprine milk is one of animal protein sources with high nutrition and relatively easy to digest. Caprine milk has high protein content (3.4%) which is potential to produce bioactive peptides. Protease is an enzyme capable to hydrolyze protein, and thus is used to hydrolyze protein to produce bioactive peptide. Fragments of protein and peptide hydrolysates can be determined by SDS PAGE analysis that show protein profiles in the form of protein molecular weight. In this study, papain was used to produce bioactive peptides from caprine milk. The objective of this study was to analyze the profile of peptides from caprine casein hydrolyzed with papain, and analyze their bioactivity as antibacteria toward food pathogens bacteria Escherichia coli and Staphylococcus aureus. The caprine casein was produced by adding HCl to defatted caprine milk until isoelectric point and coagulated by centrifugation. Hydrolysis process was performed by incubating casein and whey with papain in optimum condition (pH 7, 50°C) for 15, 30, and 45 min. Hydrolysis was terminated by heating at 80°C, 15 minutes and then stored at -20°C. Culture of pathogenic bacteria that used in this study was Escherichia coli ATCC 25 922 and Staphylococcus aureus ATCC 25923. Protein and peptides samples that have been sterilized with membrane filter (0.45 μm) were analyzed the protein profile by SDS-PAGE (consisted of 15% running gel for casein samples, 20% running gel for whey samples, 4% stacking gel and subjected to electrophoresis at constant voltage and current of 70 volt and 50 mA) and the antibacterial activity by disc diffusion method and contact method. Caprine milk has ten protein bands with molecular weight of 68, 60, 55, 34, 24, 21, 19, 18, 15 and 11 kDa. After separation, all protein bands were maintained in casein with addition of 12 kDa protein bands, whereas whey has six protein bands with molecular weight of 85, 69, 61, 25, 14, and 12 kDa. Caprine casein hydrolysis by papain enzyme, hydrolyzed α-casein (MW 32 kDa), β-casein (MW 24 kDa) and other caprine milk protein after 15 minutes incubation leaving κ-casein (MW 21 kDa) and one new peptide band (MW 10 kDa). Papain hydrolyzed lactoferrin protein in whey that can be a factor which reduce the antibacterial activity in whey. Both casein, whey and their peptide hydrolysates inhibited E. coli but not S. aureus. Further analysis showed that casein (unhydrolyzed) reduced E. coli growth significantly by 2.8 log after 2 hours exposure and the inhibition increased by exposure time.
Keyword: antibacterial, bioactive peptides, caprine milk, papain, SDS-PAGE

Judul: Tree berdiameter lima adalah graceful
Abstrak: This manuscript presents some proofs that every tree of diameter five is graceful. A graceful tree is a graph which has a graceful labelling. This labelling assigns absolute difference of connected vertices, such that the resulting edge labels are mutually distinct. There are three theorems to be considered. First theorem proves that every tree of diameter four is graceful. Second theorem proves that every tree of diameter five is graceful or nearly graceful. The third theorem improves the second theorem and shows that every tree of diameter five is nearly graceful, which can be transformed into graceful using some certain patterns.
Keyword: Graf, Pelabelan graceful, Bogor Agricultural University, Institut Pertanian Bogor, IPB