Judul: Eksplorasi bakteri selulolitik penghasil polihidroksialkanoat(PHA)
Abstrak: Mikroorganisme kini telah banyak dimanfaatkan dalam bidang industri. Polihidroksialkanoat (PHA) merupakan cadangan makanan dan karbon yang diakumulasi bakteri di dalam selnya dan bisa digunakan sebagai bahan baku plastik biodegradabel. Penelitian ini bertujuan untuk mendapatkan bakteri selulolitik yang teridentifikasi mampu menghasilkan PHA dari berbagai sampel di alam yang diambil dari beberapa lokasi di Pulau Jawa dan Kalimantan Tengah. Penelitian ini dilakukan pada bulan Februari-November 2003 di Laboratorium Mikrobiologi dan Bioteknologi Lingkungan, Pusat Penelitian Lingkungan Hidup, Institut Pertanian Bogor. Berdasarkan hasil penelitian, didapatkan sebanyak 15 isolat bakteri pendegradasi selulosa yang mampu menghasilkan PHA di dalam selnya. Indikasi adanya zona bening disekitar koloni sel setelah dilakukan pewarnaan iodium menunjukkan bahwa isolat tersebut mampu mendegradasi selulosa. Uji kemampuan akumulasi PHA 15 isolat tersebut dilakukan dengan pewarnaan Sudan Black B, xylene, dan safranin, dengan indikasi adanya granul yang berwarna kehitaman atau kebiruan di dalam sel bakteri sedangkan sitoplasma berwarna merah ketika diamati di bawah mikroskop dengan perbesaran 1000x. Sepuluh dari 15 isolat bakteri selulolitik yang dapat menghasilkan PHA, diidentifikasi lebih lanjut menggunakan Microbact 12E (Australia). Sepuluh isolat tersebut adalah: Pseudomonas sp (ICBB 7122), Alcaligenes sp (ICBB 7123), Micrococcus sp (ICBB 7124), Microbacterium lacticum (ICBB 7125 dan ICBB 7126), Citrobacter freundi (ICBB 7127), Corynebacterium sp (ICBB 7128), Bacillus brevis (ICBB 7129), Shigella sp (ICBB 7130), Bacillus pumilus (ICBB 7131).
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Judul: Isolation and Screening of PHA Producing Halotolerant Actinobacteria from High Salinity Environment
Abstrak: Plastik konvensional menjadi masalah lingkungan yang genting dihadapi oleh umat manusia akibat dari persistensinya di lingkungan hidup. Hal ini menyebabkan pencarian alternatif terhadap plastik tersebut menjadi sebuah urgensi. Salah satu alternatifnya yaitu polihidroksialkanoat (PHA), biopolimer termoplastik yang dapat disintesis oleh beragam jenis bakteri sebagai cadangan energi termasuk aktinobakteri yang merupakan salah satu filum terbesar di kelompok bakteri. Biaya produksi yang tinggi dari polihidroksialkanoat mengarahkan eksplorasi terhadap mikroorganisme halotoleran (ekstremofil) sebagai sumber produk. Oleh karena itu, penelitian ini bertujuan mengisolasi aktinobakteri halotoleran penghasil polihidroksialkanoat (PHA). Isolat-isolat yang digunakan diisolasi dari berbagai lingkungan bersalinitas tinggi di Indonesia. Setelah dimurnikan isolat-isolat yang didapatkan kemudian ditumbuhkan pada media induksi ISP9-I dan ditapis dengan menggunakan zat warna Sudan Black B dan Nile Red. Polimer yang diekstraksi dari isolat yang positif kemudian dikuantifikasi dan divalidasi menggunakan analisis gravimetrik dan uji asam krotonat. Analisis gravimetrik menunjukkan produktivitas PHA oleh isolat HVB mencapai 78,426%, sedangkan uji asam krotonat memvalidasi dan menunjukkan hasil 1,982% poli(3-hidroksibutirat) (P3HB) yang mengindikasikan tipe heteropolimer., Conventional plastics have become an urgent environmental problem for human due to their persistence in the environment. This issue has led to the exploration of alternatives. One of them is polyhydroxyalkanoates (PHA), a thermoplastic biopolymer synthesized by various bacteria as an internal energy storage compound, including actinobacteria, one of the largest Gram-positive bacteria phylum. However, the high production cost of PHA is a significant factor contributing to its non-competitiveness in the market. This has led to the exploration of halotolerant bacteria (extremophiles) as a potential producer of PHA. Therefore, this study aims to isolate indigenous PHA producer halotolerant actinobacteria. The actinobacteria used in this study were isolated from various high-salinity environments in Indonesia. After purification, isolates were cultured in ISP9-I broth media and screened by using Sudan Black B and Nile Red dyes. The extracted polymer from both positive screenings was then quantified and validated using gravimetric analysis and crotonic acid assay. The analysis showed PHA productivity by HVB can reach up to 78,426% of the dry cell weight, whereas the crotonic acid assay showed 1,982% of the extract is poly(3-hydroxybutyrate) (P3HB), indicating that extracted the polymer is a heteropolymer.
Keyword: extremophiles, Gram positive, PHA, plastic, P3HB

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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