Judul: Aktivitas Antioksidan dan Antiglikasi dari Aktinobakteri Rizosfer dan Endofit Xylocarpus granatum.
Abstrak: Pemanfaatan bakteri endofit seperti aktinobakteri merupakan salah satu cara alternatif untuk memperoleh senyawa bioaktif yang sama dengan tumbuhan induknya. Penelitian ini bertujuan mengidentifikasi senyawa dari aktinobakteri rizosfer dan endofit Xylocarpus granatum yang memunyai aktivitas antioksidan dan antiglikasi. Supernatan kultur aktinobakteri diekstraksi menggunakan etil asetat dengan nisbah 1:1 (v/v). Aktivitas antioksidan diuji menggunakan 2,2-difenil-1- pikrilhidrazil. Kromatografi lapis tipis bioautografi dan uji fitokimia digunakan untuk memprediksi senyawa aktif. Kemampuan antiglikasi ditetapkan berdasarkan penghambatan pembentukan advanced glycation end products. Sebanyak 15 isolat aktinobakteri telah diisolasi dari rizosfer, buah, dan daun X. granatum. Lima isolat dari rizosfer, dua isolat dari buah, dan tiga isolat dari daun telah diuji aktivitasnya sebagai antioksidan dan antiglikasi. Isolat XR2 memiliki aktivitas antioksidan tertinggi dengan nilai IC50 1719 mg/L. Sementara itu, aktivitas antiglikasi tertinggi dimililiki oleh isolat XR8 dengan nilai IC50 328 mg/L. Ekstrak etil asetat aktinobakteri rizosfer lebih berpotensi sebagai antioksidan dan antiglikasi dibandingkan aktinobakteri endofit.
Keyword: aktinobakteri, antiglikasi, antioksidan, Xylocarpus granatum

Judul: Xylocarpus granatum Endophytic Actinobacteria: Presence and Activity of Antioxidants
Abstrak: Xylocarpus granatum menghasilkan berbagai senyawa bioaktif dengan aktivitas biologis yang beragam, salah satunya sebagai antioksidan. Aktinobakteri endofit juga dapat menghasilkan senyawa bioaktif. Penelitian ini bertujuan untuk mengetahui keberadaan aktinobakteri endofit X. granatum dan mengetahui aktivitas antioksidannya. Metode penelitian diawali dengan isolasi aktinobakteri endofit dari buah, biji, dan daun menggunakan media selektif Humic acid (HV). Selanjutnya dilakukan karakterisasi isolat yang diperoleh menggunakan empat media berbeda yaitu YSA, ISP2, ISP3, dan ISP4. Aktivitas antioksidan dari supernatant aktinobakteri dan ekstrak etil asetat aktinobakteri dilakukan menggunakan metode DPPH. Hasil penelitian menunjukkan bahwa dari X. granatum diperoleh 15 isolat aktinobakteri endofit dari buah, biji, dan daun. Isolat aktinobakteri endofit X. granatum menunjukkan perbedaan warna pada miselium aeria dan miselium substrat, serta perbedaan penataan rantai spora. Supernatan XGF11, XGF12, dan XGF4 menghasilkan aktivitas antioksidan tertinggi yaitu: 57.30%, 49.77%, dan 41.90% penghambatan. Kapasitas antioksidan ekstrak etil asetat XGF12 adalah 501.60 μg AEAC/mg ekstrak, 465.47 μg AEAC/mg ekstrak untuk ekstrak etil asetat XGF11, dan 455.53 μg AEAC/mg ekstrak untuk ekstrak etil asetat XGF4. Ekstraksi DNA aktinobakteri endofit dilakukan berdasarkan Presto Mini gDNA Bacteria Kit. Berdasarkan hasil analisis gen 16S rRNA, isolat XGF11 dan XGF12 menunjukkan kemiripan masing-masing 99.42% dan 99.16% dengan Streptomyces xylanilyticus SR2-123 dan XGF4 memiliki kemiripan 99.82% dengan Brevibacterium sediminis FXJ8.269., Xylocarpus granatum produces various bioactive compounds with diverse biological activities, one of them as an antioxidant. Endophytic actinobacteria can also produce bioactive compounds. This study aimed to explore the existence of the endophytic actinobacteria of X. granatum and determine its antioxidant activity. The research method begins with the isolation of endophytic actinobacteria from fruits, seeds, and leaves using selective media Humic Acid (HV). Furthermore, characterizing the obtained isolates using four different media, namely YSA, ISP2, ISP3, and ISP4. Measured antioxidant activity for actinobacterial supernatants and actinobacterial ethyl acetate extracts using the DPPH method. The results showed that from X. granatum, 15 isolates of endophytic actinobacteria were obtained from fruit, seeds, and leaves. Endophytic actinobacteria isolates from X. granatum showed different colors of aerial mycelium, substrate mycelium, and spore chain type. XGF11, XGF12, and XGF4 isolates produced high antioxidant activity of the supernatant; 57.30%, 49.77%, and 41.90% inhibition, respectively. The antioxidant capacity of XGF12 ethyl acetate extract was 501.60 μg AEAC/mg extract and 465.47 μg AEAC/mg extract for XGF11 ethyl acetate extract. DNA extraction and 16S rRNA amplification from endophytic actinobacteria X. granatum according to Presto Mini gDNA Bacteria Kit Protocol. Based on 16S rDNA gene analysis, isolates XGF12 and XGF11 showed 99.16% and 99.42% similarities with Streptomyces xylanilyticus, respectively. Meanwhile, XGF4 showed to have 99.82% similarities with Brevibacterium sediminis.
Keyword: Keragaman, DPPH, Endofit, Ekstrak etil asetat, 16S rRNA, Diversity, endophytes, ethyl acetate extract

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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