Judul: Produksi Enzim Pektinase oleh Aspergillus ustus pada Media Fermentasi Semi Padat Mengunakan Limbah Pertanian sebagai Substrat
Abstrak: Many types of enzyme are used in food manufacturing process, and pectinase is one of enzyme that is frequently used by many food industries. Pectinase can be fabricated by microorganism through fermentation process using pectin-containing-medium to boost metabolite production. The objective of this research is to determine the substrate from several agricultural wastes and to define the optimum condition of fermentation for pectinase production using Aspergillus ustus (involving substrate concentration, acidity of medium, and temperature of fermentation). There are four steps in this research including substrate preparation, analysis for substrate (pectin measurement and proximate analysis), pectinase production, and trial for optimum fermentating condition. The result shows that difference in fermentating condition will affect the activity of pectinase. The highest pectinase activity is 1.2751 U/mL and it originated from peel of Medanese tangerine. Optimum condition for pectinase production was using peel of Medanese tangerine as substrate in 10% concentration, pH 4, at temperature of 40oC.
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Judul: Pemurnian dan Karakterisasi Pektinase dari Aspergillus ustus BL5
Abstrak: Pectinase, an extracellular enzymes that degrades pectin to galacturonic acid and pectinat acid. Aspergillus has been reported as a fungi that can produce secondary metabolite and extracellular of enzymes such as hemiselulase, selulase and pectinase. Pectinase plays a vital role in processing industries such as in the production of fruit juice, in fermentation tea leaves and used also at paper and textile industry. This study aimed to purify and characterize the extracellular pectinase from Aspergillus ustus BL5. Extracellular pectinase showed optimum activity with 2% substrate concentration and pH 7, in 120 hours of incubation time with 0,6 U/mg specific activity. The crude enzyme was concentrated with PEG-6000 and ultrafiltration. The crude enzyme of pectinase was purified using Sephadex G-75 gel filtration chromatography. The partial purified enzyme has specific activity 4,14 U/mg. The purity had increase 6,94 than crude enzymes. The optimum temperature and pH were 500 C and 5. The Addition of 0.05 mM CuSO4 can increased enzyme activity to 163.87%.
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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