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: Utilization of Corn Steep Liquor as an Alternative Medium for Lactococcus Lactis in the Production of Bacteriocin
Abstrak: Limbah cair jagung (LCJ) merupakan limbah industri yang melimpah. LCJ juga dikenal sebagai sumber karbon, protein, dan vitamin sehingga mulai dimanfaatkan sebagai media alternatif untuk pertumbuhan mikroba. Selain itu, LCJ juga sudah digunakan sebagai media alternatif untuk produksi bakteriosin dari berbagai bakteri asam laktat. Penelitian ini bertujuan menggunakan LCJ sebagai media alternatif pertumbuhan Lactococcus lactis dalam menghasilkan bakteriosin. Bakteriosin yang digunakan diuji aktivitas antibakterinya terhadap Staphylococcus aureus menggunakan metode cakram. Hasilnya adalah bakteriosin yang dihasilkan dari media LCJ memberikan nilai aktivitas antibakteri lebih tinggi daripada dari media komersilnya yaitu media de Man Rogosa and Sharpe (MRS). Oleh karena itu, LCJ berpotensi dijadikan media alternatif untuk menghasilkan bakteriosin oleh bakteri asam laktat Lactococcus lactis.
Keyword: antibacterial, bacteriocin, corn steep liquor, Lactococcus lactis, Staphylococcus aureus

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.