Judul: Identifikasi Bakteri Patogen pada Permukaan Kulit Buah Mentimun (Cucumis sativus) dari Tiga Lokasi di Bogor
Abstrak: Buah mentimun merupakan produk pangan yang umum dikonsumsi tanpa pengolahan. Hal ini meningkatkan kemungkinan terdapat kontaminasi bakteri pada buah mentimun, termasuk bakteri patogen. Identifikasi bakteri patogen menjadi langkah penting bagi proses penanggulangan masalah ini. Penelitian bertujuan mengisolasi, menguji aktivitas hemolisis, mengidentifikasi molekular serta mendeteksi keberadaan gen virulensi bakteri patogen yang terdapat pada permukaan kulit buah mentimun. Bakteri diisolasi dari air rendaman buah mentimun yang diencerkan secara serial hingga 10^6. Hasil pengenceran disebar pada blood agar dan dipilih koloni dengan karakter kasat mata yang berbeda. Bakteri patogen dikonfirmasi aktivitas hemolisisnya dan dipilih isolat dengan aktivitas hemolisis sempurna untuk karakterisasi lebih lanjut. Karakterisasi dilakukan secara makroskopis dan mikroskopis. Isolat diidentifikasi secara molekuler dengan gen 16s rRNA dan dideteksi keberadaan gen virulensi plcH, toxA, dan lasB. Terdapat bakteri patogen sebanyak 10^4 CFU/gram yang dideteksi pada setiap permukaan kulit buah mentimun. Sepuluh isolat yang secara kasat mata berbeda diisolasi, dimurnikan, dan dikarakterisasi aktivitas hemolisisnya. Tiga isolat dengan aktivitas hemolisis sempurna diidentifikasi memiliki karakter Gram positif, berbentuk basil dan memiliki endospora. Identifikasi molekular menunjukan ketiga isolat memiliki kemiripan sekuens tertinggi dengan Bacillus altitudinis, Bacillus cereus, dan Bacillus xiamenensis. Seluruh isolat terdeteksi memiliki gen plcH, hanya satu isolat yang memiliki gen toxA dan tidak isolat yang memiliki gen lasB., Cucumber is a food product that is commonly consumed without processing. This increases the possibility of bacterial contamination of cucumbers, including pathogenic bacteria. Identification of pathogenic bacteria is an important step in the process of overcoming this problem. The research aims to isolate, test hemolysis activity, molecular identification and detect the presence of virulence genes for pathogenic bacteria on the surface of cucumber skin. Bacteria were isolated from cucumber soaking water which serially diluted to 106. The dilution was spread on blood agar and colonies with different visible characteristics were selected. Pathogenic bacteria were re-confirmed for their hemolysis activity and isolates with perfect hemolysis activity were selected for further macroscopic and microscopic characterization. Isolates were identified molecularly using the 16s rRNA gene and detected the presence of the virulence genes plcH, toxA, and lasB. There is pathogenic bacteria around 10^4 CFU/gram detected on each surface of the cucumber skin. Ten isolates that were different isolated, purified, and re-characterized hemolysis activity. Three isolates with perfect hemolysis activity were selected and identified as Gram-positive, basil-shaped and had endospores. Molecular identification showed that three isolates had the highest sequence similarity to Bacillus altitudinis, Bacillus cereus, and Bacillus xiamenensis. All isolates were detected to have the plcH gene, only one isolate had the toxA gene and no isolates had the lasB gene.
Keyword: bakteri patogen, buah mentimun, sayuran segar, virulensi

Judul: Identifikasi Molekuler Cendawan Patogen Penyakit Busuk Buah Cabai, Terung, Tomat, Jambu dan Pepaya
Abstrak: Tanaman hortikultura merupakan komoditas penting di Indonesia. Produktivitas dan produksi komoditas ini seringkali terkendala faktor abiotik maupun biotik, termasuk masalah penyakit busuk pada buah yang dipanen yang disebabkan berbagai jenis penyebab. Penyakit busuk buah oleh cendawan patogen memiliki gejala serupa yaitu dimulai dengan bercak kecil berwarna coklat, berlanjut dengan pembusukan yang meluas dan disertai tanda patogen berupa miselium atau struktur lainnya. Identifikasi cendawan tertentu berdasarkan gejala maupun morfologi seringkali kurang memadai untuk membedakan spesies. Metode molekuler dapat menjadi pelengkap identifikasi cendawan karena memiliki efisiensi dan akurasi yang tinggi. Contoh buah cabai, tomat, terong, pepaya, dan jambu yang sakit dari lapangan diisolasi untuk mendapatkan biakan murni. Koloni biakan murni diamati dan dilakukan ekstraksi DNA genomik. Identifikasi cendawan dengan PCR menggunakan primer universal ITS5/ITS4 untuk menghasilkan amplikon yang kemudian dilakukan sikuensing. Runutan nukleotida hasil sikuensing tersebut yang dianalisis dengan BLAST menunjukkan tingkat homologi tertinggi dengan cendawan yang tersimpan data nukleotidanya dalam GenBank sebagai berikut: isolat AW1 cabai dengan Colletotrichum acutatum (Korea) sebesar 99.15%, isolat AW2 tomat dengan Fusarium lichenicola (China) sebesar 99.28% , isolat AW3 terung dengan Fusarium falciforme (Belanda) sebesar 99.64%, isolat AW4 pepaya dengan Lasiodiplodia theobromae (Taiwan) sebesar 100%, dan isolat AW5 jambu Fusarium verticillioides (China) sebesar 100%. Pohon filogenetika menggunakan MEGA X juga menunjukkan bahwa isolat AW2, AW3 dan AW5 yang berafiliasi dengan Fusarium membentuk kekerabatan yang berdekatan dan terpisah dari AW1 dan AW4. Isolat AW1 (Colletotrichum) juga terpisah cluster dari AW4 (Lasiodiplodia).
Keyword: Colletotrichum, Fusarium, internal transcribe spacer (ITS), Lasiodiplodia, nucleotide analysis, polymerase chain reaction (PCR)

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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