Judul: Karakterisasi enzim hidrolase bakteri dari mata air soda Parbubu, Tapanuli Utara
Abstrak: North Tapanuli has a soda fountain as a source of potential biotic diversity of Indonesia, one of which is the hydrolytic bacteria. The purpose of this study was to isolate bacteria from the soda fountain and test Parbubu hidrolasenya enzyme activities, ie lipase, protease, and cellulase enzyme hidrolase and characterize the best in certain conditions of temperature and pH. Isolation of bacteria from the soda fountain Parbubu using pour plate method produced 23 isolates of bacteria. Test semikualitatif hidrolase enzyme using hydrolytic enzymes in media index showed that the bacterial isolates P9 has the highest lipase activity. Harvest time P9 bacterial lipase based on the growth curve and enzyme production curves, ie on the seventh hour of incubation. Lipase activity determined with titrimetric method shows that the fraction of the enzyme by precipitation (60-80)% of ammonium sulfate has the highest activity, that is equal to 3.5245 U / mL or 5992 times the activity of crude extract. Lipase enzyme has optimum activity at pH 7, at 5.9593 U / mL and at a temperature of 90 º C with the activity of 4.9019 U / mL.
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Judul: Isolasi dan Optimasi Protease Bakteri Termofilik dari Sumber Air Panas Tangkuban Perahu Bandung
Abstrak: Protease is an enzyme widely used in food industry. Thermophilic bacteria produce protease that can withstand high temperature. The research was aimed to isolate thermophilic bacteria and characterize protease of isolates with highest proteolytic index. Isolation was carried out on 33 isolates from three hot springs. Isolation was done by using pour plate method. Protease activity was measured by Bergmeyer, and protease characterization was conducted at pH 6-10 and temperature of 50oC- 90oC. The results showed that two isolates from Sipaholon hot spring, eleven isolates from Tangkuban Perahu hot spring, and two isolates from Ciseeng hot spring established clear areas around their colonies. T8 isolate derived from Tangkuban Perahu hot spring showed the highest proteolytic index of 33.5 and was used for further testing. The highest proteolytic activity of T8 isolate was obtained at 21th hour amounted to 3.8375 x 10-3 U/mL. Protease activity increased in ammonium sulphate 60% fraction, which was 7.7257 x 10-3 U/mL. Statistical analysis showed that pH and temperature affected protease activity. The optimum protease activity was obtained at pH 8 Clark & Lubs buffer and temperature of 60oC.
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Judul: The Construction of Greedy SVP LLL Algorithm
Abstrak: A lattice is a set of all integer linear combination of a set of linearly independent vectors in ℝ𝑛���. The independent vectors are called bases of lattice. Any lattice can be generated from many bases, and these bases have the same cardinality. In the lattice, the most fundamental and renowned problem is the Shortest Vector Problem (SVP). SVP is a tracking problem of the shortest nonzero vector in a lattice with equivalent bases. In two dimensions, SVP problem has resolved exactly by Gauss’ algorithm. When the lattice dimension is higher than two, A.K. Lenstra, H.W. Lenstra and L. Lovasz gave a LLL algorithm to compute approximation of nonzero shortest vector in the lattice. Reduced bases solution obtained from LLL algorithm still be an approximation and has polynomial running time of arbitrary dimension which large enough. In 1994, Schnoor and Euchner modified this LLL algorithm as a new variant which later was named deep insertion LLL algorithm. This algorithm is a modified version of the LLL algorithm to the terms of the exchange step to improve the accuracy of output of LLL reduced bases and applying it to the subset sum problem. The purpose of this research are: (1) Reconstruct the LLL algorithm and deep insertion LLL algorithm using a geometric approach. (2) Construct a greedy SVP LLL algorithm. (3) Implement the three algorithms in a symbolic programming language, and evaluate them experimentally. A bases ℬ=[𝐛���1,𝐛���2,…,𝐛���𝑛���] in ℝ𝑚��� is called reduced LLL with parameter 𝛿��� if satisfies: (a) |𝜇���𝑗���𝑖���|≤12, for every integer 𝑖���,𝑗��� with 1≤𝑖���<𝑗���<𝑛���. (b)𝛿���‖𝜋���𝑗���(𝐛���𝑗���)‖2≤‖𝜋���𝑗���(𝐛���𝑗���+1)‖2, for 𝑗���=1,2,…,𝑛���−1,where 𝛿��� is a reduced parameter of real numbers with 14<𝛿���<1. The first requirement is the reduced basis 𝛿��� must “nearly orthogonal” and in its computation case, this requirement can be reached out by using the Gram-Schmidt’s orthogonalization. While the second requirement is called exchange step, or used to called as Lovasz condition. By using both of these requirements, then they establish the LLL algorithm. Then, Schnoor and Euchner modify the LLL algorithm based on the requirements of the exchange step called the deep insertion LLL algorithm, where the exchange step is based on the comparison of the projected vector in orthogonal complement [𝐛���1,𝐛���2,…,𝐛���𝑘���−1]⊥ after j-th reduction. To construct greedy SVP LLL algorithm, the requirements of the exchange step is based on purely by comparing norm of lattice 𝐛���𝑗��� with norm lattice 𝐛���𝑖��� for 𝑖���=1,2,3…,𝑗���−1. The process of insertion reduced vector after the exchange step also has done greedily. Then, we calculate the number of arithmetic operation in greedy SVP LLL algorithm for further analysis. The result of our exprimentation for three algorithms on the certain matrix size shows that the running time of the three algorithms increases propotional to the size of the matrix. The result also shows that by using 𝛿���=34 for the LLL algorithm and the deep insertion LLL algorithm, and the greedy SVP LLL algorithm which is a new variant made by using no parameter of 𝛿���, outperform of the other of two previous algorithm in terms of speed with the same output.
Keyword: LLL algorithm, LLL deep insertion algorithm, greedy SVP LLL algorithm