Judul: Xylitol Production from Sugarcane Bagasse Hydrolysate by Immobilized Cell Candida tropicalis and Candida guilliermondii.
Abstrak: Xilitol merupakan gula alkohol berkarbon lima yang banyak digunakan di bidang farmasi, kesehatan, dan pangan. Xilitol mempunyai harga tinggi tetapi ketersediaan xilitol dalam perdagangan masih rendah. Produksi xilitol secara komersial masih memiliki hambatan yaitu biaya produksi mahal, karena diperlukan energi yang tinggi (proses hidrogenasi) dan bahan baku xilosa murni. Oleh karena itu dibutuhkan teknik produksi alternatif yang lebih murah dengan memanfaatkan mikroba dan hidrolisat ampas tebu. Penelitian ini bertujuan mengoptimasi produksi xilitol dengan amobilisasi sel Candida tropicalis dan Candida guilliermondii serta pengaruh penambahan nutrien pada media hidrolisat ampas tebu. Fermentasi dilakukan pada suhu 30oC dengan kecepatan pengadukan 120 rpm. Pengukuran kadar xilitol ditentukan dengan metode spektrofotometer menggunakan kit D-sorbitol/D-xilitol pada panjang gelombang 492 nm. Hasil penelitian menunjukkan teknik amobilisasi sel mampu meningkatkan hasil produksi xilitol yaitu pada jam ke 96 diperoleh kadar xilitol 12.28 g/L untuk sel amobil dan 10.84 g/L untuk sel bebas. Sel Candida tropicalis menghasilkan produk xilitol lebih tinggi dibanding Candida guilliermondii. Kadar xilitol yang dihasilkan sel amobil Candida tropicalis diperoleh sebesar 12.28 g/L dari konsentrasi xilosa 30 g/L dan sel amobil Candida guilliermondii diperoleh 2.8 g/L. Perlakuan penambahan nutrien ekstrak khamir diperoleh kadar xilitol sebesar 17 g/L dan penambahan nutrien KH2PO4 menghasilkan kadar xilitol tertinggi, yaitu 20.31 g/L dan nilai rendemen 0.68 g/g.
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Judul: Penambahan Glukosa sebagai Kosubstrat dan Pengaruhnya terhadap Produksi Xilitol oleh Candida guilliermondii
Abstrak: Xylitol is a five-carbon sugar alcohol and used commercially in various fields. Xylitol can be produced by solid-liquid extraction from fruits and vegetables, also chemical synthesis which is expensive and energy-intensive. Therefore, an alternative inexpensive production techniques is required, one of them is using microorganism. The purposes of this research were to determine the optimum incubation time for the growth of C. guilliermondii, and xylitol production, also to determine the best ratio variation of glucose:xylose. Fermentation was carried out at 300C with shaking speed 120 rpm. Ratio variation used in this research were (glucose:xylose) 1:25, 1:12, 1:5, 1:2.5. Xylitol concentration was measured with spectrophotometer based on D-sorbitol/Dxylose Kit. The results showed the log phase of the growth of C. guilliermondii at 12-36 hour, and the optimum incubation time to obtain the highest amount of xylitol at 72 hour. The best variation ratio of glucose:xylose is 1:5 with initial glucose concentration 9 g/L and xylose concentration 45 g/L. Xylitol obtained from ratio 1:5 was 2.85 g/L while xylitol obtained from control medium, which is the medium that contained only xylose 45 g/L was 0.57 g/L, thus the addition of glucose to fermentation medium can increase the production of xylitol.
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Judul: Implementation of Spatio-Temporal Change Query in Relational Database.
Abstrak: Geographic object changes in various views. Object changes are recorded using a model of static storage. No historical connection between old version data and new version data has been built. For that, a storage model of spatio-temporal queries that can analyze spatio-temporal changes has been developed. The object changes the geometry are grouped according to the taxonomy of Spatio-Temporal Pattern Change. This research has been able to apply the query patterns change including born, expand, merge, contract, split, normal and die. This query based on geometric (area) changes. The implementation of spatio-temporal change queries represents an object changes continuously with easy, change detection is done by comparing two versions of data. Keyword: spatio-temporal change query, spatio-temporal change pattern.
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