Judul: Characterization of Cellulase from Marine Fungi RS6A and Its Application for Hydrolysis of Kappaphycus alvarezii
Abstrak: Hidrolisis secara enzimatis diketahui memiliki keunggulan diantaranya yaitu secara spesifik menghasilkan oligosakarida, ramah lingkungan dan tidak berpotensi meninggalkan residu toksik. Kapang RS6A dimanfaatkan dalam proses hidrolisis rumput laut K. alvarezii sebagai penghasil enzim selulase untuk memisahkan komponen lignoselulosa dan oligosakarida. Penelitian ini bertujuan menentukan pengaruh perbedaan waktu inkubasi dan konsentrasi CMC terhadap aktivitas selulase, menentukan waktu inkubasi dan konsentrasi CMC terbaik untuk produksi enzim selulase dan menentukan waktu hidrolisis rumput laut K. alvarezii menggunakan enzim selulase dari isolat kapang RS6A. Analisis data aktivitas selulase yang digunakan dalam penelitian ini adalah rancangan acak lengkap faktorial dua faktor. Konsentrasi sumber karbon dan waktu inkubasi yang menghasilkan aktivitas selulase optimum yaitu CMC 2% dan inkubasi enam hari. Ekstrak kasar selulase memiliki aktivitas selulase optimum sebesar 0,071±0,001 U/mL, aktivitas endoglukanase sebesar 0,197±0,035 U/mL, dan aktivitas spesifik selulase sebesar 0,088±0,009 U/mg. Hidrolisis selama 3 jam menghasilkan persentase hidrolisis selulosa sebesar 73% dan persentase hidrolisis lignin sebesar 4,8%., Enzymatic hydrolysis potentially offers many advantages, such as specific hydrolysis resulting in the production of target oligosaccharides, environmentally friendly and without produce toxic residual molecules. Fungi RS6A was applied in the hydrolysis of algae K. alvarezii as a cellulase enzyme producer to separated lignocellulose and oligosaccharide. The objectives of this research were to determine the effect of differences in incubation time and concentration of CMC on cellulase activity, determine the best incubation time and concentration of CMC for cellulase enzyme production and determine the hydrolysis time of K. Alvarezii. Data analysis of cellulase used in this research was completely randomized factorial design with two factors. The incubation time for 6 days and treatment of 2% CMC showed the highest cellulase activity of 0.071±0.001 U/mL, the highest endoglucanase activity of 0.197±0.035 U/mL and the highest specific cellulase activity of 0.088±0.009 U/mg. Hydrolysis for 3 hours showed cellulose hydrolysis degree of 73% and lignin hydrolysis degree was 4.8%.
Keyword: cellulase, hydrolysis, marine fung

Judul: Ultrasound-Assisted Depolymerization of Carrageenan from Kappaphycus alvarezii Hydrolysis by Marine Endophytic Fungi RS6A
Abstrak: Kappaphycus alvarezii merupakan spesies rumput laut penghasil kappakaragenan. Karagenan merupakan polisakarida yang terbentuk dari unit Dgalaktosa dan 3,6-anhidrogalaktosa yang dihubungkan oleh ikatan α-1,3 dan β-1,4- glikosidik. Proses hidrolisis K. alvarezii dilakukan secara enzimatis dengan memanfaatkan kapang RS6A sebagai penghasil enzim selulase untuk mengekstrak karagenan. Penelitian bertujuan menentukan waktu ultrasonikasi yang optimal dalam proses depolimerisasi karagenan. Perlakuan diberikan pada proses depolimerisasi dengan perbedaan waktu ultrasonikasi (0, 30, 60 dan 90 menit). Viskositas karagenan diukur menggunakan viskometer Brookfield, yang kemudian digunakan untuk menghitung bobot molekul melalui persamaan Mark-Houwink. Nilai viskositas dan bobot molekul yang diperoleh bervariasi antara 3.73-6.13 cP dan 35.58-52.15 kDa, serta memiliki korelasi terbalik dengan waktu ultrasonikasi. Hasil tersebut menunjukkan ultrasonikasi efektif menurunkan bobot molekul dalam proses depolimerisasi. Perlakuan terpilih diperoleh ultrasonikasi selama 30 menit dengan kesesuaian standar sesuai SNI dan FAO., Kappaphycus alvarezii is a species of seaweed that produces kappacarrageenan. Carrageenan is a polysaccharide formed from D-galactose and 3,6- anhydrogalactose units which linked by α-1,3 and β-1,4 glycosidic bonds. The hydrolysis process of K. alvarezii was carried out enzymatically by fungus RS6A as a cellulase enzyme producer to extract carrageenan. This study aims to determine the optimal ultrasonication time in the carrageenan depolymerization process. Treatment was given on depolymerization process with differences in ultrasonication time (0, 30, 60 and 90 minutes). Carrageenan viscosity was measured using Brookfield viscometer, which was then used to calculate the molecular weight by Mark-Houwink equation. The viscosity and molecular weight values varied between 3.73-6.13 cP and 35.58-52.15 kDa, and had an inverse correlation with the ultrasonication time. These results indicate that ultrasonication was effective in reducing molecular weight in the depolymerization process. The selected treatment was obtained by ultrasonication for 30 minutes with conformity to standards according to SNI and FAO.
Keyword: depolimerisasi, hidrolisis enzimatis, karagenan, ultrasonikasi., carrageenan, depolymerization, enzymatic hydrolysis, ultrasonication.

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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