Judul: Karakterisasi zat antzmmroba-polpeptida dari isolat Bacillus sp. LTW 54 Asal tambak udang
Abstrak: Vibriosis merupakan penyakit yang umum menyerang larva udang yang disebabkan oleh bakteri Vibrio harveyi. Penggunaan bakteri probiotik merupakan salah satu alternatif yang dapat digunakan untuk menanggulangi penyakit tersebut. Bakteri probiotik yang banyak digunakan sebagai biokontrol dalam budidaya udang ialah Bacillus sp karena bakteri tersebut dapat menghasilkan zat antimikroba-polipeptida bakteriosin.
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Judul: Karakterisasi Zat Antimikrob Penghambat Pertumbuhan Vibrio harveyi Dan Escherichia coli Dari Bacillus sp.Asal Tambak Udang
Abstrak: Penyakit udang merupakan masalah umum yang terjadi di tambak. Salah satu bakteri patogen penting ialah Vibrio harveyi. Aplikasi bakteri probiotik dapat dijadikan sebagai kontrol untuk menanggulangi pertumbuhan bakteri patogen ditambak. Bacillus sp. merupakan suatu kelompok bakteri yang secara luas digunakan sebagai probiotik di akuakultur. Bakteri ini dapat menghasilkan zat antimikrob polipeptida sebagai bakteriosin dalam menghambat pertumbuhan bakteri lain. Objek dari studi ini untuk menyeleksi isolat Bacillus sp. dari tambak udang dan mengkarakterisasi zat antimikrob polipeptida yang dihasilkan oleh Bacillus sp. Tiga isolat Bacillus sp. diuji aktivitas antimikrobnya terhadap V. harveyi dan E. coli. Dari hasil menunjukkan bahwa Bacillus sp. Lts 40 mempunyai aktivitas antimikrob paling besar. Uji kompetisi juga menunjukkan isolat Bacillus sp. Lts 40 dapat menghambat pertumbuhan V. harveyi 81,8% dan E. coli 85,5%. Zat antimikrob ini diproduksi selama fase pertumbuhan dan produksi optimum setelah 3 hari inkubasi. Zat antimikrob polipeptida yang dihasilkan Bacillus sp. Lts 40 stabil pada kisaran pH 3-11 dan zat antimikrob ini juga stabil setelah diperlakukan dengan panas sampai 100 0C selama 20 menit. Hasil purifikasi dengan kromatografi filtrasi gel bahwa fraksi no 21 efektif dalam menghambat pertumbuhan V. harveyi dengan berat molekul 47,3 kDa dan fraksi no 29 efektif dalam menghambat pertumbuhan E. coli dengan berat molekul 34,83 kDa.
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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