Judul: Isolation and characterization lactid acid bacteria producing bacteriocins from corn fermented milk
Abstrak: Corn milk is one of diversification product in the society as a nutrition source selection than staple food. Corn milk is low durability due to contamination spoilage bacteria. The use of chemical preservatives can be used to keep the spoilage bacteria contamination but these preservatives are very harmfull to humans. The research study purpose is isolation and identification of lactid acid bacteria producing bacteriocin from fermented corn for biopreservatives on corn milk. Isolation of lactid acid bacteria (LAB) from fermented corn was done spontaneously with 3 treatments and 2 replications. The first treatment of the tube was opened and not heated (JMB), the tube was closed and not heated (JMT) and the tube was closed and heated (JMA). Screening LAB performed was used the best flavour as a organoleptic test. The selected LAB as the best organoleptic characteristics, also able to maintain the flavor after 6 months of storage at 40C of temperature. The bacteria was found will be selected by direct antagonism method with stab inoculation againts indicator bacteria strain Staphylococcus aureus and Escherichia coli. The bacteria that produced a clear zone was chosen to next selection by using well diffusion method. The LAB screening results of organoleptic tests and producing antimicrobial compounds then observed of growth phase. The 13 isolates were tested by using well diffusion methods which used S. aureus as microbial test in pH 4, pH 6 after that protease treatments. Consumer acceptance of the BAL inoculation were measured and analyzed using hedonic value based Fredman test. The chosen bacteria was identification by 16S rRNA. Total of 33 isolates were obtained. The first until third treatment obtained 22, 7, and 5 isolates respectively. The selected LAB is a bacteria by the widest clear zone is Lactobacillus JMB 9, Lactobacillus JMB 13 dan Lactobacillus JMT 6. Lactobacillus JMB 4 and Lactobacillus JMB 6 as BAL candidate who can give the best flavor. Direct antagonist screening method obtained 13 isolates that produce inhibitory effects on Sthapylococcus aureus and E.coli. Based on the screening results obtained Lactobacillus JMB 6 has the ability to produce inhibition in pH 6. The addition of protease make a disturb of bacteriocins activity. The antimicrobial substance produced by Lactobacillus JMB 6 can be concluded as a bacteriocins. The addition of bacteriocins treatment and inoculation of lactic acid bacteria showed preference value not significantly different scents. Bacteriocins added and bacterial selected inoculation on corn milk showed that all treatments have the ability to retain flavor. Identification bacterial based on 16 sRNA was showed 97% similarity LAB JMB 4 with Lactobacillus plantarum.
Keyword: Lactic acid bacteria (LAB), sweet corn, fermented milk, bacteriocin

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. ,,,
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular.