Judul: Seleksi dan Optimasi Aktivitas Biodegradasi Senyawa Piren serta Identifikasi Molekuler Bakteri Laut
Abstrak: Piren merupakan salah satu jenis kelompok senyawa Polisiklik Aromatik Hidrokarbon (PAH) berbobot molekul tinggi sehingga sulit didegradasi di lingkungan. Teknik biodegradasi dengan menggunakan bakteri laut indigenous digunakan sebagai upaya mengurangi polutan piren yang bersifat karsinogenik. Tujuan penelitian ini adalah melakukan seleksi dan optimasi aktivitas biodegradasi senyawa piren oleh bakteri laut serta identifikasi dengan metode 16S rDNA. Hasil penelitian pada uji sublimasi menghasilkan 16 isolat positif yang terbagi menjadi 3 kelompok isolat yaitu 5 isolat berdasarkan perubahan warna, 6 isolat pembentuk zona bening dan 5 isolat pembentuk keduanya. Uji pertumbuhan menyatakan terdapat 4 isolat unggul dalam mendegradasi senyawa piren yaitu isolat LBF-1-0114, LBF-0132, LBF-1-0137, dan LBF-1-0140. Isolat LBF-1-0114 dan LBF-1-0137 mampu mendegradasi senyawa piren secara optimum pada konsentrasi piren 250 ppm. Isolat LBF-1-0132 dan isolat LBF-1-0140 menghasilkan konsentrasi piren optimum 650 ppm. Keempat isolat tersebut menghasilkan konsentrasi sel optimum (OD600nm) sebesar 20. Hasil identifikasi 16S rDNA bakteri laut menyatakan bahwa LBF-1-0114 merupakan Stenotropomonas sp., LBF-1-0132 merupakan Pseudomonas aeruginosa, LBF-1-0137 adalah Halomonas sp., dan LBF-1-0140 merupakan spesies Bacillus statosphericus.
Keyword: piren, optimasi, identifikasi molekuler 16S rDNA

Judul: Optimasi Biodegradasi Senyawa Dibenzotiofen dan Identifikasi Molekuler pada Bakteri Laut.
Abstrak: Tumpahan minyak bumi yang sering terjadi di laut akibat kegiatan ekploitasi merupakan salah satu sumber pencemaran lingkungan. Dibenzotiofen merupakan salah satu komponen minyak bumi yang termasuk zat polutan berbahaya dan sulit terdegradasi di lingkungan. Penelitian ini bertujuan melakukan optimasi biodegradasi senyawa dibenzotiofen dengan parameter konsentrasi dibenzotiofen dan konsentrasi sel serta identifikasi molekuler pada bakteri laut melalui analisis 16S rDNA. Berdasarkan hasil seleksi secara kualitatif melalui uji sublimasi, terdapat 19 isolat bakteri laut yang memiliki kemampuan dalam mendegradasi senyawa dibenzotiofen. Hasil seleksi secara kuantitatif berdasarkan uji pertumbuhan terpilih dua isolat bakteri yang unggul dalam mendegradasi dibenzotiofen yaitu isolat LBF-1-0022 dan LBF-1-0062. Isolat LBF-1-0022 memiliki kondisi optimum dalam biodegradasi senyawa dibenzotiofen pada konsentrasi dibenzotiofen 750 ppm dan konsentrasi sel 30.6 x 108 CFU/mL. Kondisi optimum biodegradasi senyawa dibenzotiofen oleh isolat LBF-1-0062 yaitu pada konsentrasi dibenzotiofen 50 ppm dan konsentrasi sel 40.8 x 108 CFU/mL. Berdasarkan hasil analisis gen 16S rDNA pada bakteri laut, isolat LBF-1-0022 dan LBF-1-0062 teridentifikasi sebagai spesies Stakelama pacifica dan Pseudomonas sp.
Keyword: bakteri laut, dibenzotiofen, minyak bumi

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