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"Keragaman dan Komposisi Asam Lemak Bakteri Lipolitik Isolat Asal Tanah dan Sedimen Perairan Wilayah Hutan dan Perkebunan Sawit. Bakteri spesifik dalam hutan dan perkebunan kelapa sawit adalah bakteri lipolitik. Enzim-enzim dari bakteri lipolitik telah diaplikasikan di agro-akuakultur, makanan, deterjen, farmasi, industri susu, dan biodiesel-biokerosin. Penelitian bertujuan memberikan informasi keragaman bakteri lipolitik asal tanah dan sedimen perairan di areal hutan dan perkebunan kelapa sawit, dan komposisi asam lemaknya. Sampel tanah berasal dari tanah lapisan atas hutan dataran rendah dan perkebunan kelapa sawit dan sedimen air tawar di dekat situs tersebut. Hutan tersebut terletak di Taman Nasional Bukit Duabelas dan perkebunan kelapa sawit sekitarnya di Kabupaten Sarolangun, Jambi, Indonesia. Sebanyak 22 isolat terpilih dari tiga puluh dua isolat bakteri lipolitik yang tumbuh pada media selektif lipolitik, terdiri dari 11 isolat dari tanah lapisan atas dan 11 isolat dari sedimen air di hutan dan daerah perkebunan. Isolat-isolat bakteri diidentifikasi berdasarkan analisis gen 16S rRNA. Hasil identifikasi menunjukkan isolat-isolat tersebut terdiri atas lima genera yaitu Burkholderia, Cupriavidus, Serratia, Acinetobacter, dan Kurthia. Pada pohon filogenetik yang dibangun menggunakan metode maximum likelihood isolat-isolat tersebut terdistribusi ke dalam tiga grup, yaitu grup Burkholderia-Cupriavidus, grup Serratia-Acinetobacter, dan grup Kurthia. Hasil analisis kromatografi gas (GC-FID) menunjukkan bahwa enzim lipolitik yang dihasilkan bakteri-bakteri tersebut terdiri atas berbagai asam lemak. Beberapa isolat bakteri menghasilkan asam lemak esensial, seperti asam lemak: linoleat, linolenat, arakidonat, eikosapentanoat (EPA), dan dokosaheksanoat (DHA).

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The specific bacteria in forests and on oil palm plantations are lipolytic bacteria. Their enzymes have been applied in the agro-aquaculture, food, detergent, pharmaceutical, dairy, and biodiesel-biokerosene industries. This study describes the diversity of cultivable lipolytic bacteria from soil and aquatic sediment in a forest and on an oil palm plantation and their fatty acid products. Soil samples used in this research were obtained from topsoil in a lowland forest and on an oil palm plantation and from sediments in fresh water near these sites. The forest is located in Bukit Duabelas National Park, and the oil palm plantation is near the forest in Sarolangun District, Jambi Province, Indonesia. Twenty-two isolates of lypolitic bacteria were selected from 32 isolates grown in lipolytic selective medium. The 22 consisted of 11 isolates from topsoil and 11 from aquatic sediment from the forest and plantation area. These isolates were identified by 16S rRNA-sequence data analysis. Taxonomically, they belonged to five genera: Burkholderia, Cupriavidus, Serratia, Acinetobacter, and Kurthia. The maximum likelihood tree showed that they are phylogenetically distributed in three clusters. They were clustered into three groups: the Burkholderia-Cupriavidus group, the Serratia-Acinetobacter group, and the Kurthia group. Their lipolytic enzymes formed various fatty acids after analysis by gas chromatography-flame ionization detector (GC-FID). Some isolates formed essential fatty acids, such as linoleic, linolenic, arachidonic, eicosapentanoic acid (EPA), and docosahexanoic acid (DHA)."

"We suggest a chemical model for the composition and atmospheric processing of mixed organic-inorganic aerosol. The PITZER modelwas modified and parameterized to betterdescribe atmospheric relevant conditions and mixture compositions. Using the wide range of data for the following systems containing malonic acid (H2Malo): H+? Na+? HMalo-? Cl-?H2Malo ? H2O and H2Malo ? H2SO4? H2O. With these modifications the activities of inorganicsalt solutions and acids are well represented up to high ionic strength. The first model is a result of mixtures containing NaCl, water and either malonic acid, succinic, oxalic, glutaric or adipicat room temperature. The parameterization of direct inorganic/organicinteractions strongly improves the agreement between experimentaland modelled activity coefficients for thediacids/ water/ salt solutions. The system compositions are given in terms of ions in the cases where acid dissociation was considered. Tropospheric aerosols contain a mixture of inorganicsalts, acids, water and organic compounds. Aninteraction between neutral or charged components in such a mixture leads to discrepancies from ideal thermodynamic behavior.Using component activities instead of molar concentrations one can count for this non idea behavior."

"Peran dan perilaku asam organik pada pelindian bijih nikel lateritik diamati dalam eksperimen berikut sebagai alternatif dari proses pelindian asam anorganik, HPAL (High-Pressure Acid Leaching). Eksperimen dilakukan dengan menggunakan dua tahapan (sequensial), yaitu pelindian elemen besi menggunakan asam oksalat (C2H2O4) dan diikuti dengan pelindian nikel dan kobalt menggunakan asam sitrat (C6H8O7). Secara spesifik, efek dari beragamnya suhu pelindian, konsentrasi asam organik, dan waktu pelindian telah diamati. Dengan ini, memperoleh konklusi bahwa suhu dan waktu sangat mempengaruhi proses pelindian. Meningkatkan suhu pelindian hingga 90 oC dapat menghilangkan 49% besi dan hanya memulihkan 3% nikel dan 8% kobalt. Hasil eksperimen juga membuktikan bahwa semakin lama waktu pelindian, maka pemulihan nikel dan kobalt semakin tinggi dan selektif. Sementara itu, pada konsentrasi asam organik yang tinggi, pemulihan nickel dan kobalt tidak terlalu efektif. Data eksperimen dianalisa menggunakan XRF/XRD dan ICP-OES.

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The role and behaviour of organic acids in the leaching of nickel laterite ore were investigated in the following experiments as an alternative to the leaching process of inorganic acids, HPAL (High-Pressure Acid Leaching). Experiments were carried out using two steps (sequential); firstly, leaching of iron using oxalic acid (C2H2O4) and followed by leaching of nickel and cobalt using citric acid (C6H8O7). Specifically, the leaching parameters such as temperature, organic acid concentration, and leaching time were observed. The experiment concluded that temperature and time have greatly impact on the leach process. Increasing the leaching temperature to 90 oC with 1 M of oxalic acid concentration can remove 49% of iron with only 3% nickel and 8% cobalt were recovered. The experimental results also prove that longer leaching time resulted in higher and more selective nickel and cobalt recovery. Meanwhile, at a high concentration of citric acid, the recovery of the nickel and cobalt were not very effective. Experimental data were analysed using XRF / XRD and ICP-OES. "