Judul: Isolasi dan identifikasi mikroorganisme indigenus dan aplikasinya pada fermentasi jagung serta karakterisasi sifat fisikokimia tepung yang dihasilkan
Abstrak: Corn is an important carbohydrate source in Indonesia. Local white corn is currently being developed including Anoman 1 (high amylose) and Pulut Harapan (low amylose) varieties. However, the utilization of corn flours and/or starches in native form have a less desirable physicochemical properties, especially with regards to retrogradation, syneresis, and low stability of pasta at high temperature and low pH properties. Consequently, there is a need to modify flour properties to increase the utilization. Traditionally, corn flour is made by soaking corn kernels in water. The spontaneous fermentation occurred during soaking and affected the physicochemical properties, but it’s difficult to achieve a consistent product. The purpose of this study to identify microorganisms that play a role in the fermentation process of corn, as well as the process of fermentation with the addition of a starter culture and studied the physicochemical properties of corn flour produced. The research was conducted in : (1) to isolate and identify microorganims which the role play during spontaneous fermentation of white local corn of Anoman 1 variety; (2) to design a starter culture of the microorganisms isolated to use for a controlled fermentation; (3) do the fermentation by adding a starter culture and characterize physicochemical properties of corn flour produced. Treatments consisted of: Spontaneous fermentation, i.e. water soaking of corn grits (as a control, SF); and fermentation with added starter culture containing microbes previously isolated without toxigenic microbe (CC); and (AC) fermentation of (CC) with additional amylolytic microbes after 16 hours of fermentation. The number of each microorganisms that added were 106 CFU / mL; (4) to study the physicochemical properties of corn flours of Anoman1 and Pulut Harapan varieties produced. Observations were done at 0, 36, 48, and 72 hours fermentation. The results showed that there were 16 microorganisms were identified included 8 species of molds (Penicillium chrysogenum, Penicillium citrinum, Aspergillus flavus, Aspergillus niger, Rhizopus stolonifer, Rhizopus oryzae, Fusarium oxysporum, Acremonium strictum), 3 species of yeasts (Candida famata, Kodamaea ohmeri, Candida krusei/incospicua), and 5 species of lactic acid bacteria, LAB (Lactobacillus plantarum1a, Pediococcus pentosaceus, L. brevis1, L. plantarum1b, and L. paracasei ssp paracasei3). Four molds and one yeast were amylolytic while none of the lactid acid bacteria (LAB). One from 8 species of molds identified was producing aflatoxin i.e. Aspergillus flavus. While all of yeasts and LAB species identified was non-toxigenic. So, the Aspergillus flavus was not used as a starter culture. All of non-toxigenic microbes identified, there were three (3) species of mold (Penicillium citrinum, Aspergillus niger, Acremonium strictum) and one (1) species of yeast (Candida famata) that were amylolytic, while all of LAB identified were non-amylolytic. The amylase activity changed during spontaneous fermentation (SF), where the activity was a maximum at 12 hours of fermentation. After that activity tended to decrease up to 72 hours of fermentation. To study the influenced of amylase activity to the flour during fermentation, was made the amylolytic culture that added after 16 hours fermentation to increase the activity . In general it can be concluded that the fermentation process caused the changes in the physicochemical properties of corn
Keyword: isolation, identification, microorganisms, physicochemical properties

Judul: Isolation of lactic acid and cellulolytic bacteria and their application to improve the quality of corn flour
Abstrak: Corn has the potential to be converted into flour, but the hard endosperm causing coarse particle size, corn flour also do not have a long shelf life and induce the production of mycotoxin. To overcome these problems, the milling of corn grain can be done by steeping it in the water. Steeping process caused spontaneous growth of microbes, such as lactic acid and cellulolytic bacteria. Lactic acid bacteria in the steeping process produce antimicrobial and antifungal compounds that are able to control the growth of pathogenic bacteria, spoilage bacteria, and fungi. The use of lactic acid and cellulolytic bacteria in the steeping process can soften the horny endosperm, so it can improve the corn grits to grind into fine flours. Based on the role of both microbes, the consortium of bacteria inoculated as starter in the steeping process of corn grits. It was expected that the introduction of starter would shorten the steeping time, improve the fine flour yield, and suppress the growth of undesired microbes. This study aimed to obtain isolates of indigenous lactic acid and cellulolytic bacteria from corn steeping process, and to apply them as a starter in the steeping process of corn grits to increase the quality of corn flour. The experiment conducted into three steps: analysis of microbial population dynamics in spontaneous fermentation of corn grits during steeping process, isolation and selection of lactic acid and cellulolytic bacteria, and the use of starter in the steeping process of corn grits. Population dynamics of microbes during spontaneous fermentation is the basic rule for the formulation of appropriate starter culture. The fermentation during steeping process conducted for 0, 12, 24, 36, and 48 hours. The amount of lactid acid bacteria increased until 48 h of steeping and the population of cellulolytic, amylolytic, and yeast increased until 36 hours. In this study, only lactic acid and cellulolytic bacteria were isolated and used as a starter. Amylolytic bacteria and yeast were not used to prevent the damage of starch, and yeasts are generally found at the end of fermentation. Seven LAB isolates and 10 cellulolytic bacteria isolates were obtained from the 48 hours of spontaneous fermentation, and 10 cellulolytic bacteria isolates from 12 hours of fermentation. Isolate E2213BAL (BAL) was lactic acid bacteria selected as the highest optical density at logarithmic phase, while isolate B2121SLT (BST) was cellulolytic bacteria with the highest enzyme activity. The use of starter in the fermentation of corn was done by steeping the corn grits in sterile distilled water containing bacterial starter. Both microbes were inoculated into steeping water according to the composition starter: control without starter (A), 106 CFU/ml of BAL:106 CFU/ml of BST (B), 106 CFU/ml of BAL:2X106 CFU/ml of BST (C) , 2X106 CFU/ml of BAL:106 CFU/ml of BST (D). During the fermentation, the number of lactic acid, cellulolytic, amylolytic bacteria, and yeast growths from inoculated fermentation (B, C, D) were higher compared to spontaneous fermentation (A). 7 During the fermentation, the pH of steep water decreased as the increasing of total acidity. Treatment D with 36 hour steeping time produced the highest
Keyword: cellulolytic bacteria, corn flour, fermentation, lactic acid bacteria

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