Judul: Kinetika Fermentasi Produksi Bioetanol Menggunakan Fermentor pada Medium Sintetis Bersenyawa Inhibitor
Abstrak: Hidrolisat lignoselulosa mengandung senyawa inhibitor yang menyebabkan stres inhibitorik pada khamir penghasil bioetanol. Tujuan penelitian ini adalah mengetahui parameter kinetika S. cerevisiae BTCC 3 selama proses fermentasi pada berbagai medium sintetis dengan konsentrasi inhibitor yang berbeda berdasarkan model kinetik tak terstruktur. Fermentasi dilakukan dalam sistem batch selama 48 jam tanpa pengulangan dengan glukosa dan xilosa sebagai sumber karbon. Konsentrasi sel, gula, bioetanol, dan senyawa inhibitor dianalisis dengan spektrofotometer (600 nm) dan HPLC untuk penentuan parameter kinetika fermentasi. Hasil yang diperoleh menunjukkan bahwa peningkatan konsentrasi inhibitor memberikan efek negatif pada laju pertumbuhan sel spesifik (μ), laju pertumbuhan sel spesifik maksimum (μmax), konsentrasi sel maksimum (Xmax), rendemen biomassa (YX/S), dan rendemen biomassa pertumbuhan (YX/S(growth)), namun sebaliknya memberikan efek positif pada laju konsumsi substrat spesifik (qS), laju pembentukan produk spesifik (qP), laju pemeliharaan sel spesifik (m), dan konstanta saturasi (Ks). Selain itu, peningkatan konsentrasi inhibitor tidak mempengaruhi rendemen produk (YP/S) dan laju kematian sel spesifik (Kd). Hasil evaluasi menunjukkan bahwa model memiliki rentang nilai RMSE (Root Mean Square Error) dan R2 (koefisien determinasi) masing-masing adalah 0,0158-0,4902 dan 0,9014-0,9992. Dengan kata lain, model kinetik yang digunakan dalam penelitian ini cukup baik dalam menggambarkan dan memprediksi proses fermentasi oleh strain BTCC 3 dalam berbagai medium pada fermentor skala 3 L.
Keyword: fermentor, khamir, kinetika fermentasi, model kinetik tak terstruktur, stres inhibitorik

Judul: Analisis dan Identifikasi Khamir Toleran Senyawa Inhibitor pada Hidrolisat Lignoselulosa
Abstrak: Khamir merupakan organisme fungi uniseluler yang mampu menghasilkan etanol melalui proses fermentasi. Salah satu substrat penting dalam proses fermentasi yaitu lignoselulosa. Lignoselulosa merupakan biomassa berlimpah yang tersusun atas selulosa dan hemiselulosa, yang harus diolah menjadi hidrolisat sebelum dapat digunakan dalam proses fermentasi etanol. Dalam pengolahan hidrolisat lignoselulosa, akan terakumulasi senyawa inhibitor berupa asam organik, furfural, dan fenol yang dapat menghambat pertumbuhan dan metabolisme khamir, sehingga menurunkan laju fermentasi etanol. Penelitian ini bertujuan menyeleksi dan mengidentifikasi khamir toleran senyawa inhibitor pada hidrolisat lignoselulosa. Analisis resistensi khamir terhadap senyawa inhibitor menunjukkan isolat E dan R memiliki ketahanan tinggi terhadap cekaman furfural 0.10% (v/v), sedangkan isolat E, R, dan T memiliki ketahanan tinggi terhadap cekaman asam asetat 0.375% (v/v). Induksi resistensi dengan penambahan prolin mampu meningkatkan sifat toleran isolat E, R, T terhadap cekaman furfural 0.15% (v/v) dan asam asetat 0.50% (v/v), sedangkan induksi resistensi dengan penambahan hidrogen peroksida (H2O2) tidak memberikan pengaruh terhadap pertumbuhan khamir. Isolat khamir E, R, dan T menghasilkan kadar etanol yang lebih tinggi daripada Saccharomyces cerevisiae. Identifikasi molekuler menunjukkan isolat E memiliki homologi sebesar 95% dengan Pichia kudriavzevii strain AUMC 10225, isolat R memiliki homologi sebesar 93% dengan P. kudriavzevii strain Y4 dan isolat T memiliki homologi sebesar 97% dengan P. kudriavzevii.
Keyword: Furfural, asam asetat, prolin, bietanol

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