Judul: Produksi dan Karakterisasi  Bakteriosin Asal Lactobacillus  plantarum  1A5 serta Aktivitas Antimikrobanya  terhadap Bakteri Patogen
Abstrak: The aims of this research were to study antimicrobial activity of bacteriocin produced by lactic acid bacteria Lactobacillus plantarum 1A5 in six different media (media with NaCl 1%, combination of NaCl 1% and YE 3%, and trypton 1% inducers that were conditioned on pH 5 dan pH 6, respectively). Characteristic of bacteriocin 1A5 determined by catalase and proteolytic enzymes with antagonistic assay against pathogenic bacterias (Staphylococcus aureus ATCC 25923, Salmonella typhimurium ATCC 14028 and enteropathogenic Escherichia coli K11) and determination of Minimum Inhibitory Concentration (MIC) and Minimum Bactericide Concentration (MBC)’s value against Staphylococcus aureus ATCC 25923. The result showed that the inhibitory activity was produced significantly by crude bacteriocin 1A5 from media with trypton 1% inducer and was conditioned at pH 6. Characterization of active compound from crude bacteriocin 1A5 could be classified as bacteriocin neither antimicrobial compounds such as hydrogen peroxide because it was stable to catalase treatment. The other characteristic of its bacteriocin was nature proteinaeous that showed loss it’s activity after trypsin treatment against Staphylococcus aureus ATCC 25923 and enteropathogenic Escherichia coli K11, neither Salmonella typhimurium ATCC 14028. Inhibition activity of crude bacteriocin 1A5 could explained with MIC and MBC’s value, especially against Staphylococcus aureus ATCC 25923. MIC’s and MBC’s value needed respectively 70% dan 80% concentration of crude bacteriocin.
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Judul: Production of Crude Bacteriocin Lactobacillus plantarum 2C12, 1A5, 1B1, 2B2 from Beef and Their Antimicrobial Activity Against Patogenic Bacteria
Abstrak: Bacteriocin is an antimicrobial peptides produced by lactic acid bacteria which can be a safe biopreservatif agent. The production of bacteriocin have to be done to replace the existence of synthetic preservatives which cause diseases and have been used to decrease the contamination of spoilage and pathogenic bacteria that can be found in many food material. The lactic acid bacteria which used in this research were the isolates of Lactobacillus plantarum 2C12, 1A5, 1B1 and 2B2, that have been isolated from local beef and deposited at Animal Science Faculty of Bogor Agriculture University. This research has been done from February to August 2011. The aims were to learn about the growth curves of L. plantarum 2C12, 1A5, 1B1 and 2B2, to identify the antimicrobial activity of crude bacteriocin from some different isolates lactic acid bacteria and their effects of to some indicator bacteria by diffusion well method agar. The observed variable in this research was the inhibitation zone around the well which refer to the antimicrobial activity from bacteriocin to indicator bacteria and it has been explained by Completely Randomized Design (CRD) with factorial arrangement 5x4. The results of this research showed that all isolates of L. plantarum (2C12, 1A5, 1B1 and 2B2) had some antimicrobial compounds which could decrase the indicator bacteria’s growth, such as Salmonella entritidis ser. Thypimurium ATCC 14028, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Bacillus cereus, dan Staphylococcus aureus ATCC 25923.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular