Judul: Enzyme Purification: Phytase of Klebsiella aerogenes
Abstrak: Tanaman adalah sumber pangan yang penting bagi manusia. Produk pangan dari tanaman yang dikonsumsi oleh sebagian besar bangsa di dunia berasal dari biji-bijian dan kacang-kacangan. Akan tetapi, biji-bijian dan kacang-kacangan tersebut selain mengandung zat yang dibutuhkan oleh tubuh seperti lemak, protein, karbohidrat, mineral dan vitamin, juga mengandung zat antigizi, yaitu asam fitat. Asam fitat atau garam-garamnya merupakan bentuk utama penyimpanan fosfor pada biji-bijian serealia dan kacang-kacangan. Interaksi fitat dengan protein, vitamin, dan beberapa mineral dianggap sebagai faktor penting yang membatasi nilai nutrisi biji-bijian dan kacang-kacangan. Senyawa ini sangat sukar dicerna sehingga fosfor dalam bentuk fitat tidak dapat dimanfaatkan oleh tubuh. Oleh karena itu, hidrolisis fitat melalui raksi enzimatis sangat dibutuhkan. Penurunan fitat melalui reaksi enzimatis dilakukan oleh fitase (EC 3.1.3.8), yaitu enzim yang mampu menghidrolisis fitat menjadi ortofosfat dan mio-inositol. Fitase dapat diperoleh dari mikroorganisme termasuk mikroorganisme yang diisolasi dari tanah, yaitu Klebsiella aerogenes. Pemurnian enzim fitase dari Klebsiella aerogenes dilakukan dengan pengendapan (NH4)2SO4 70% jenuh, dialisis, pengeringan beku serta filtrasi gel menggunakan matriks Superdex G-75. Pada tahap pengeringan beku, enzim fitase dari Klebsiella aerogenes menunjukkan kerentanannya yang ditandai oleh hilangnya sebagian aktivitasnya. Enzim hasil pemurnian memiliki aktivitas spesifik sebesar 3,3172 Unit/mg protein dengan tingkat kemurnian 37,36 kali. Kondisi optimum reaksi hidrolisis fitat adalah pada pH 7,0 dan suhu 45°C. Peningkatan kemurnian yang jauh lebih besar daripada tahap-tahap pemurnian sebelumnya menunjukkan bahwa enzim fitase telah terpisah dengan baik.
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Judul: Karakterisasi enzim fitase dari Bacillus coagulans
Abstrak: Fitase (EC 3.1.3.8) merupakan enzim yang mampu mengkatalisis reaksi hidrolisis asam fitat (mio- inositol heksakisfosfat), sejenis ester fosfat yang dapat mengikat mineral dan protein sehingga sulit diserap tubuh. Pemanfaatan fitase untuk menurunkan kadar asam fitat dalam bahan makanan perlu memperhatikan karakteristik enzim, agar aktifitas enzim berlangsung pada kondisi yang optimal. Fitase yang diproduksi dari Bacillus coagulans diendapkan dengan penambahan amonium sulfat hingga 70 % jenuh dilanjutkan dengan dialisis. Fraksi enzim hasil dialisis kemudian dikarakterisasi. Fraksi dialisis memiliki aktifitas spesifik 0,5676 U/mg protein dengan kemurnian 1,5 kali. Fitase Bacillus coagulans memiliki aktifitas optimum pada suhu 40°C dan pH 6.0. Enzim ini mengalami penurunan aktifitas bila konsentrasi substrat > 0,7 mM. Nilai KM yang diperoleh dari kurva Lineweaver- Burk sebesar 0,562 mM dengan kecepatan maksimum 0,731 µmol PO4/menit/ml. Fitase Bacillus coagulans mengalami penghambatan aktifitas oleh penambahan 1 mM Fe* dan Fe, namun Ca2+, dan Mn** pada konsentrasi yang sama dapat meningkatkan aktifitasnya. Mg2+,
Keyword: enzymes

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