Papers by Rizmahardian A Kurniawan
Sample preparation using cellulolytic bacteria fermentation has been reported improving oil isola... more Sample preparation using cellulolytic bacteria fermentation has been reported improving oil isolation from plants. Yet, the effect of fermentation to oil composition was not investigated. Therefore, in this research, we compared oil composition of Pontianak orange peel with and without cellulolytic fermentation. Bacteria used for cellulolytic fermentation were previously isolated from Pontianak peat land soil. The isolates were Yersinia pseudotuberculosis RAG25 and Proteus penneri RAG31. Analysis using GCMS showed major volatile compound, limonene, was unchanging, while minor volatile compound such as n-nonanal and n-dekanal, was not appeared after fermentation. ABSTRAK Preparasi sampel menggunakan fermentasi bakteri selulolitik telah diketahui mampu meningkatkan rendemen minyak yang diisolasi dari tanaman. Walaupun demikian, pengaruh fermentasi tersebut terhadap komposisi minyak yang diperoleh masih belum banyak diinvestigasi. Dalam penelitian ini, komposisi minyak kulit jeruk Pontianak akan dibandingkan dengan sampel yang diawali tahap preparasi berupa fermentasi bakteri selulolitik. Bakteri yang digunakan untuk fermentasi adalah isolat Yersinia pseudotuberculosis RAG25 dan Proteus penneri RAG31 yang telah diisolasi dari tanah gambut Kota Pontianak. Analisis yang dilakukan menggunakan GCMS menunjukkan bahwa komponen utama minyak kulit jeruk yaitu limonen tidak berubah. Akan tetapi, komposisi minor minyak asiri kulit jeruk seperti n-nonanal dan n-dekanal, tidak muncul setelah dilakukan fermentasi. Kata kunci: bakteri selulolitik, fermentasi, jeruk Pontianak, senyawa asiri 1. PENDAHULUAN Rendemen minyak asiri kulit jeruk Pontianak dapat ditingkatkan dengan memberikan perlakuan awal sebelum proses ekstraksi dilakukan. Salah satu cara yang dapat digunakan adalah dengan memberikan perlakuan menggunakan enzim selulase atau melakukan fermentasi kulit jeruk Pontianak sebelum didistilasi. Penelitian
Biocathode for biofuel cell was prepared by covalently immobilizedLaccaseon CNT (CNT-Laccase) usi... more Biocathode for biofuel cell was prepared by covalently immobilizedLaccaseon CNT (CNT-Laccase) using glutaraldehyde as conjugates. Successful laccase immobilization was confirmed by Fourier Transform Infrared (FTIR) Spectrophotometry, Surface Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). Immobilization affected Laccase enzymatic activity where it boosts the stability at high temperature and neutral pH. At temperature 65ºC, free Laccase completely loss its activity, while CNT-Laccase still retaining 57.12% of its activity at 45ºC. The activity of CNT-Laccase at pH 7 was 7.04% of activity at pH 5 which was higher than that of free Laccase. CNT-Laccase was able to perform oxygen electroreduction with addition ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as mediator. Performance of oxygen electroreduction activity was also determined by type and composition of binding polymer. Nafion was able to provide better environment for oxygen electroreduction activity compare to polyvinyl alcohol (PVA). Current density resulted in using Nafion in ratio 1:10 to buffer volume was 1.31 mA/cm2, which was higher than that of PVA (1.01 mA/cm2). Increasing binding polymer ratio into 1:2 and 1:1 undermined oxygen electroreduction activity.
Marine invertebrate -associated bacteria are one of potential and prolific sources to produce uni... more Marine invertebrate -associated bacteria are one of potential and prolific sources to produce unique and novel structure of bioactive compounds. Unsuitable growth media for cultivation of bacteria result in many bioactive compounds were not produced. Moraxella sp. RA15 was successfully isolated from Acropora dibranchiata. In an attempt to introduce bioactive compounds of Moraxella sp. RA15 was evaluated through various media and bioassays to find out the antimicrobial, antiplasmodial, and herbicidal potency as well as toxicity property. The Moraxella sp. RA15 extract in 1/10ZoBell agar medium showed herbicidal activity, toxicity against brine shrimp and antimicrobial activity against Bacillus subtilis, Pseudomonas aeruginosa, and Staphylococcus aureus. The antiplasmodial activity was only showed by Moraxella sp. RA15 extract produced in 1/10ZoBell broth medium. It can be concluded that medium and culture condition are important factors in bioactive compound production from bacteria.
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Papers by Rizmahardian A Kurniawan