Judul: Screening and Characterization of Marine Endophytic Fungi Producing Extracellular Enzymes
Abstrak: Marine endophytic fungi are a group of endophytic microbes that colonize and live within the tissues of their host organisms, such as seaweed, seagrass, and mangroves. Marine endophytic fungi produce extracellular enzymes, namely protease, cellulase, and chitosanase. This study aims to screen the potential of extracellular enzymes from marine endophytic fungi, identify the isolates of marine endophytic fungi, and characterize the extracellular enzymes produced. The research methods carried out include refreshing, evaluating potential, producing enzymes, then identifying them morphologically and molecularly, as well as testing the specific activity of enzymes. The screening results showed that out of 20 isolates, 50% produced clear zones on skim milk media, 40% on carboxyl methyl cellulose (CMC) media, and 60% on colloidal chitosan media. Three isolates with the highest clear zone indices for protease, cellulase, and chitosanase were identified as Penicillium citrinium KTR45, Fomitopsis sp. KTR47, and Aspergillus terreus KTR51, respectively. The specific activities of protease, cellulase, and chitosanase enzymes were 5.475,42±2,724,25 U/mg, 620,77±607,71 U/mg, and 4.487,32±721,73 U/mg, respectively.
Keyword: Enzyme, biocatalyst, marine endophytic fungi, symbion

Judul: Isolation and Selection of Chitosanolytic and Cellulolytic Endophytic Fungi from Different Seaweeds
Abstrak: Oligokitosan sebagai oligomer kitosan telah banyak dimanfaatkan untuk berbagai aplikasi biologis. Oligokitosan dapat diproduksi dengan metode enzimatis. Produksi oligokitosan dengan depolimerisasi kitosan secara enzimatis membutuhkan penggunaan enzim spesifik seperti kitosanase atau non-spesifik seperti selulase yang dapat diperoleh dari kapang endofit yang bersimbiosis dengan biota laut. Penelitian bertujuan mendapatkan isolat, mengkarakterisasi dan menyeleksi kapang endofit dari rumput laut dengan aktifitas kitosanolitik dan selulolitik, serta identifikasi kapang endofit yang potensial menghasilkan enzim kitosanolitik dan selulolitik. Penelitian dilakukan dengan tahapan isolasi, penapisan aktivitas enzim, identifikasi morfologi dan molekuler kapang endofit. Sebanyak 42 isolat kapang endofit berhasil diisolasi dari rumput laut. Satu isolat kapang memiliki aktivitas kitosanolitik dan berjumlah 24 isolat memiliki aktivitas selulolitik dengan kategori indeks selulolitik sedang hingga rendah. Secara molekuler, isolat kapang endofit kitosanolitik dan selulolitik teridentifikasi sebagai Neoantrodia serialis (KTR2), Trichoderma harzianum (KTR3, KTR4) dan Apiotrichum mycotoxinovorans (KTR1). Enzim kitosanolitik dan selulolitik kapang endofit rumput laut kedepannya dapat dikembangkan menjadi alternatif untuk produksi berbagai oligomer secara enzimatis, salah satunya yaitu oligokitosan., Oligochitosan as an oligomer of chitosan has been widely utilized for various biological applications. Oligochitosan can be produced by enzymatic methods. The production of oligochitosan by enzymatically depolymerizing chitosan requires the use of specific enzymes such as chitosanase or non-specific enzymes such as cellulase that can be obtained from endophytic fungi that are symbiotic with marine biota. The research aims to obtain isolates, characterize and select endophytic fungi from seaweed with chitosanolytic and cellulolytic activities, and identify endophytic fungi that have the potential to produce chitosanolytic and cellulolytic enzymes. The research was conducted with the stages of isolation, screening of enzyme activity, morphological and molecular identification of endophytic fungi. A total of 42 endophytic fungi isolates were successfully isolated from seaweed. One isolate had chitosanolytic activity and 24 isolates had cellulolytic activity with moderate to low cellulolytic index categories. Molecularly, the chitosanolytic and cellulolytic endophytic fungi isolates were identified as Neoantrodia serialis (KTR2), Trichoderma harzianum (KTR3, KTR4) and Apiotrichum mycotoxinovorans (KTR1). The chitosanolytic and cellulolytic enzymes of seaweed endophytic fungi can be developed into alternatives for the enzymatic production of various oligomers, one of which is oligochitosan.
Keyword: enzim, rumput laut, kapang endofit, kitosanolitik, selulolitik

Judul: Pemodelan Nilai Tukar Rupiah Terhadap US Dollar Menggunakan Deret  Waktu Hidden Markov Dua Waktu Sebelumnya
Abstrak: Nilai tukar Rupiah terhadap US Dollar mengalami perubahan setiap waktunya dalam periode yang panjang dan perubahan yang terjadi mungkin terjadi kembali di masa mendatang. Jika penyebab kejadiannya tidak diamati secara langsung dan membentuk suatu rantai Markov maka perubahan nilai tukar Rupiah dapat dimodelkan dengan model deret waktu hidden Markov. Untuk menggambarkan perilaku nilai tukar Rupiah terhadap US Dollar, dalam karya ilmiah ini digunakan model deret waktu hidden Markov dua waktu sebelumnya. Model ini mengasumsikan bahwa nilai tukar Rupiah terhadap US Dollar bergantung pada rantai Markov yang merupakan penyebab kejadian yang tidak diamati dan nilai tukar Rupiah dua waktu sebelumnya.
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