Judul: Produksi dekstranase dari isolat Streptococcus sp B7 dalam bioreaktor 20 liter
Abstrak: Dalam industri gula tebu, dekstran sering menimbulkan masalah dengan meningkatkan viskositas cairan gula. Hal ini dapat menyebabkan penyumbatan pipa dan mengurangi rendemen. Untuk mengatasi masalah tersebut maka diman- faatkan enzim yang dapat menghidrolisa dekstran, yaitu dekstranase. Penelitian ini bertujuan untuk memproduksi dekstranase dari isolat Streptococcus sp B7 dalam bioreaktor Bioen- gineering berkapasitas 20 liter. Selain itu juga dilakukan penelitian terhadap penggunaan dekstrin sebagai substrat alternatif, karena harganya yang lebih murah daripada dekstran. Produksi dekstranase dengan substrat dekstrin dilakukan dalam labu erlenmeyer yang diinkubasi dalam shaker. Perlakuan yang digunakan adalah pH dan kecepatan agitasi. Kecepatan agitasi yang digunakan sebesar 300 rpm dan 500 rpm, sedangkan pH sebesar 7 dan 8. Aktivitas tertinggi diperoleh pada perlakuan pH 8 dan kecepatan agitasi 500 rpm, yaitu sebesar 1946.67 U/ml. Untuk penggunaan substrat dekstrin dilakukan hanya perlakuan pH awal sebelum sterilisasi sebesar 7 dan 8. Aktivitas tertinggi dicapai pada perlakuan PH 8 sebesar 142.67 U/ml.
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Judul: Proses fermentasi Fed-Batch untuk produksi dekstranase dari isolat bakteri Streptococcus sp. B7
Abstrak: Penelitian ini bertujuan untuk mengembangkan teknik fermentasi pada produksi enzim dekstranase dari isolat bakteri Streptococcus sp B7 dengan mempergunakan sistem fermentasi fed-batch. Fermentasi fed-batch produksi dekstranase dilakukan pada fermentor kapasitas 2 liter dengan laju penambahan substrat 19 ml/jam dengan waktu fermentasi 3 kali 24 jam. Perlakuan yang dilakukan pada penelitian ini adalah pH dan kecepatan putaran. Perlakuan pH dilakukan pada pH 7 dan pH 8, sedangkan kecepatan putaran yang digunakan adalah 300 dan 500 rpm. Aktivitas relatif tertinggi dari semua perlakuan dicapai pada fermentasi dengan kecepatan putaran 500 rpm pada pH 8 yang mencapai 920 U/ml. Hasil terbaik ditinjau dari parameter kinetik terten- tu adalah sebagai berikut: produksi 920 U/ml, produktivi- tas 16.43 U/ml/jam, aktivitas spesifik 17.78 U/mg pro- tein, Yp/x 696.97 U/g sel dan produktivitas spesifik 12.45 U/g sel/jam.
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Judul: Characteristic of Overshooting Top (OT) Based on  Himawari  8  Satellite  as  a  Convective  Cloud  Feature  that  Generates  Extreme Weather in the Java Island Region
Abstrak: Overshooting Top (OT) is a feature at the top of a convective cloud that is associated with extreme weather. Research on OT in tropical Indonesia is still very limited. The existence of geostationary satellites with wide area coverage and fast frequency observations is useful for observing the fast dynamics of the OT life cycle. Therefore, this study intends to analyze the relationship between OT and extreme weather, updraft and thermodynamic conditions of OT when extreme weather occurs, the best objective method for detecting OT in the day time and night time, and the spatiotemporal distribution of OT in the tropical region of Java Island during the 2018-2021 period. Based on visual analysis using visible channel and Himawari 8 sandwich products, 87% of extreme weather events in Java were accompanied by the appearance of OT. It indicates that the presence of the OT pattern is a convection cloud pattern or feature that is closely related to extreme weather events for the Java Island region. The existence of a time lag between the appearance of OT and extreme weather events on Java Island indicates that the OT of convection cloud can be used as a precursor or nowcasting for the appearance of extreme weather. Most of the convective cloud OT features during extreme weather events on Java Island have altitude that were only able to exceed the altitude of the equilibrium level and few were able to exceed the tropopause level of 9 km – 16 km. The difference in atmospheric conditions during extreme weather events on Java Island, which is in the tropics and subtropics, is a strong and unstable convective energy condition characterized by a larger CAPE, as well as unstable KI, LI, SI and TTI values. It is offset by kinematic factors in the form of a weak vertical wind shear (bulk wind shear 0-6 km) and a higher freezing point height. The difference between extreme weather events in the Java Island region and other tropical regions compared to subtropical regions is the strong updraft speed of convection clouds. The IRW Texture COMB algorithm based on the IRW-Texture Gradient modification and the COMB algorithm shows a significant increase in quality for detecting OT and non-OT pixels in Java. Rainy days with rainfall > 50 mm/day are very common in areas with an altitude of > 500 m. On the other hand, the level of convection activity which is indicated by the presence of OT and lightning is significantly reduced in this area. OT of convective clouds appear more frequently during the DJF season and less frequently during the JJA season. OT often appears during the day time and rarely at night time. Most OTs appear in the central part, away from the south and north coasts of Java Island during the day, while OTs that appear near the south and north coasts of Java Island can appear in the morning or afternoon.
Keyword: convective clouds, extreme weather, Overshooting Tops, Himawari 8 Satellite