Judul: Sintesis Lacto-N-Biose I Secara Enzimatis Dari Laktosa Dan Glcnac Menggunakan Enzim Lactose Phosphorylase Dan Lacto-N-Biose I Phosphorylase
Abstrak: Lacto-N-biose I (LNB) merupakan salah satu jenis prebiotik yang saat ini telah banyak dikaji khususnya terkait aktivitasnya sebagai bifidus factor. Beberapa penelitian melaporkan bahwa LNB secara signifikan dapat meningkatkan aktivitas mikroflora yang hidup di dalam usus bayi dan balita. Senyawa ini secara alami terdapat di dalam human milk oligosaccharide, akan tetapi seiring dengan perkembangan teknologi, LNB dapat disintesis secara enzimatis. Saat ini, sintesis LNB telah banyak dilakukan, akan tetapi rendemen yang dihasilkan masih rendah dan membutuhkan waktu sintesis yang lama. Oleh karena itu, diperlukan metode yang efisien untuk menghasilkan rendemen tinggi dan dilakukan dengan waktu proses yang singkat. Diketahui bahwa enzim, substrat dan fosfat pada sintesis LNB diyakini dapat mempengaruhi rendemen yang dihasilkan. Pada penelitian ini, dilakukan sintesis LNB secara enzimatis dari laktosa dan GlcNAc dengan menggunakan enzim lactose phosphorylase (LP) dan lacto-N-biose I phosphorylase (LNBP) sebagai katalis. Tujuan penelitian ini yaitu untuk melakukan purifikasi dan karakterisasi enzim LP dan LNBP yang digunakan untuk sintesis LNB. Selain itu diteliti juga pengaruh penambahan enzim, substrat dan fosfat terhadap rendemen LNB yang dihasilkan. Preparasi kultur bakteri dilakukan meliputi transformasi plasmid, pre-kulturisasi dan kulturisasi bakteri. Kemudian dilanjutkan dengan purifikasi enzim dengan menggunakan kromatografi afinitas ion logam imobilisasi seperti: preparasi kolom, pemurnian enzim dan konsentrasi enzim. Setelah itu, dilakukan karakterisasi enzim untuk menentukan aktivitas enzim pada berbagai suhu inkubasi, pH dan konsentrasi substrat. Selanjutnya, dilakukan analisis secara kuantitatif dari sintesis LNB menggunakan high performance liquid chromatography. Hasil penelitian menunjukkan bahwa kondisi optimum katalisis enzim LP terjadi pada suhu 37oC, pH 6 dengan konsentrasi substrat 15 mM, sedangkan kondisi optimum katalisis enzim LNBP terjadi pada suhu 35oC, pH 7 dengan konsentrasi substrat 10 mM. Aktivitas spesifik enzim LP cukup tinggi (18,64 U/mg), sementara enzim LNBP sangat kecil (0,013 U/mg). Peningkatan konsentrasi enzim LP dan fosfat pada sintesis LNB tidak mempengaruhi rendemen yang dihasilkan, sedangkan konsentrasi substrat berpengaruh nyata terhadap rendemen. Sintesis LNB dari laktosa dan GlcNAc menggunakan enzim LP dan LNBP mampu menghasilkan rendemen hingga 75,3%. Metode ini dapat digunakan sebagai alternatif untuk sintesis LNB dari substrat yang lebih murah yang banyak tersedia di alam.
Keyword: prebiotik, lacto-N-biose I, laktosa, GlcNAc, LP, LNBP

Judul: Metabolisme prebiotik oleh kandidat probiotik isolat asi sebagai dasar pengembangan produk sinbiotik
Abstrak: Seven Lactobacillus strains isolated from breast milk were evaluated for their ability to metabolite oligosaccharide known as prebiotics, i. e. inulin, FOS, GOS, FOS:GOS (1:9), and inulin:GOS (1:9). The result shows that all Lactobacillus strains were able to grow in medium with prebiotics as carbon sources. The best growth was observed when GOS or FOS were used as carbon source, while inulin was the worst. The best growth in all oligosaccharides was observed in Lactobacillus R23H, followed by R23, B16, and R14. Further study on R23H and R23 shows that there was no difference in metabolizing oligosaccharides between heterofermenter and homofermenter. GOS was the best prebiotic used by the both lactic acid bacteria as shown by rapid decrease of total sugar. The reducing sugar in medium containing GOS was higher than other oligosaccharides. The decrease of total sugar in medium containing inulin was the slowest among the other prebiotics. This indicate that inulin was the most difficult prebiotic to be metabolized by the selected lactic acid bacteria. When inulin mixed with GOS in the ratio 1:9, the rate of decreasing of total sugar in the medium was similar to the medium with GOS as single carbon source, however it cannot be distinguished if the role of inulin took place after GOS disappear. The rate of sugar metabolism was in accordance with the growth of lactic acid bacteria isolates in medium containing prebiotics. Lactobacillus R23 was used in sinbiotic fermented milk product combine with FOS, inulin, and inulin:GOS (1:9). After fermentation, the result show that remaining sugar in skim milk with additional prebiotics was higher than skim milk without additional prebiotics. Remaining sugar on fermented milk product include the amount of prebiotic that will use as carbon source in colon. Combination of potential probiotic Lactobacillus R23 and mixture of inulin:GOS (1:9) could be used to make sinbiotic fermented milk product.
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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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