Judul: Genome Shuffling Lactobacillus rhamnosus dan Lactobacillus pentosus sebagai Fusant Penghasil L-Lactic Acid
Abstrak: Asam laktat terutama isomer L-lactic acid merupakan salah satu bahan tambahan pangan yang cukup luas penggunaannya, yakni sebagai perisa, pengatur keasaman dan penyusun plastik polylactic acid. Asam laktat umumnya diproduksi secara fermentasi menggunakan bakteri asam laktat. Limbah industri pangan yang mengandung hemiselulosa masih cukup melimpah sementara pemanfaatannya belum optimal. Salah satu gula hasil hidrolisis hemiselulosa adalah gula xilosa. Xilosa dapat dimanfaatkan bakteri asam laktat (BAL) seperti Lactobacillus pentosus untuk menghasilkan asam laktat. Kelemahan bakteri ini adalah asam laktat yang dihasilkan masih berupa campuran L- dan D-lactic acid. Oleh karena itu diperlukan perbaikan sifat genetik supaya asam laktat yang dihasilkan hanya L-lactic acid yakni dengan cara genome shuffling Lactobacillus pentosus dengan Lactobacillus rhamnosus. Hasil yang diharapkan dari penggabungan keduanya adalah strain baru yang mampu menggunakan xilosa sebagai subtrat dan menghasilkan produk utama berupa Llactic acid. Keunggulan genome shuffling dibandingkan rekayasa genetika secara konvensional adalah pengerjaan lebih sederhana, waktu yang dibutuhkan relatif lebih singkat serta tidak memerlukan peta genetik bakteri secara lengkap. Penelitian ini bertujuan untuk memperoleh waktu inkubasi optimal pembentukan protoplas Lactobacillus rhamnosus dan Lactobacillus pentosus serta memperoleh strain bakteri asam laktat (fusant antara Lactobacillus rhamnosus dan Lactobacillus pentosus) yang mampu menggunakan xilosa sebagai substrat dan mampu memproduksi L-lactic acid dengan menggunakan teknik genome shuffling. Penelitian terdiri dari penentuan waktu optimal pembentukan protoplas dan genome shuffling. Hasil penelitian menunjukkan bahwa kondisi optimal pembentukan protoplas L. rhamnosus adalah dengan menggunakan konsentrasi lisozim 10 mg/ml ( 200 000 U/ml) waktu inkubasi selama 2 jam sedangkan untuk L. pentosus dengan konsentrasi lisozim > 5 mg/ml (100 000 U/ml) dan waktu inkubasi 2 jam. Pada penelitian ini telah berhasil diperoleh 16 fusant yang mampu menggunakan xilosa untuk dikonversi menjadi L-lactic acid.
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Judul: Seleksi dan Optimasi Bakteri Asam Laktat Penghasil Senyawa Antikapang
Abstrak: Silage is the forage preservation product through anaerobic fermentation by using lactic acid bacteria (LAB). The presence of oxygen may activate the other microbe that could be contaminate and interrupt the silage processing. Fungi is a microbe that often contaminate silage processing. In Indonesia, prevention of silage contamination by fungi is necessary in order to support livestock business. By using the inoculum that able to produce antifungal compounds, the fungi contamination could be prevented. This research was dedicated to screen LAB having antifungal properties, taxonomic study and optimization of antifungal production. Screening of antifungal producing LAB was initiated by growing LAB on de Man Rogosa Sharpe Agar (MRSA) against Aspergillus fumigatus, A. flavus, and Penicillium by plate assay method (aerobic condition) and verified by deep tube technique (anerobic condition). The results showed that strain DR 1-6-2 could inhibit A. fumigatus and A. flavus in aerobic condition with percentage of inhibition was 41% and 32 %, respectively. In anaerobic condition, strain DR 1-6-2 could inhibit not only A. fumigatus, A. flavus, but also Penicillium. Identification of selected LAB was carried out using 16S rRNA gene sequencing with 27F and 1492R primer. Based on molecular analysis, strain DR 1-6-2 is belong to Lactobacillus plantarum with the degree of homology of 98%. Optimization of antifungal production by selected LAB was carried out using Response Surface Method (RSM) with Central Composite Design (CCD) on five variables (glucose, yeast extract, CH3COONa, K2HPO4, Tween 80) and five level combinations. From statistical analysis, the production of antifungal which is represented by the total lactic acid production of selected LAB is significantly influenced by glucose, combination of glucose and K2HPO4, combination of yeast extract and K2HPO4 and Tween 80. The optimum concentration of glucose is 2.91%, yeast extract 0.58%, K2HPO4 0.29% and Tween 80 0.19% with a maximum predicted lactic acid yield of 2.61%, which is increased by 59%. This result is confirmed when the optimum concentration of nutritions used. The production of lactic acid increased by 58%. Benefit of this research is utilization of indegenous LAB isolates as the silage inoculum and antifungi to prevention of contamination and to obtain a good silage quality. This LAB utilization is capable to trigger the silage production, which in turn could increase the silage utilization as animal feed, increasing the production of meat, and could support the government's efforts to achieve the national demand of meat product. In silage fermentation using L. plantarum DR 1-6-2, anaerobic condition is a requirement to be considered. Identification of other antifungal compounds produced by L. plantarum DR1-6-2 is need to be studied.
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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