Judul: Penapisan dan Identifikasi Bakteri Endofit dari Tanaman Binahong dan Ketepeng Cina Penghasil Senyawa Antibakteri Patogen
Abstrak: Endophytic bacteria is a beneficial microorganism that interacts with plant without causing any harm to the host. Most studies showed that certain endophytic bacteria can produce chemical compound which have medical effect for human, especially endophytic bacteria from medicinal plant. The objective of this research are to isolation endophytic bacteria from binahong and ketepeng cina that produce antibacterial compound and to identify the potencial isolate through 16S rRNA gene. Endophytic bacteria from both plants was tested to 5 human pathogenic bacteria, that are Escherichia coli dH5α, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and Enterobacter sakazakii. Endophytic bacteria isolate from binahong code BB5 and BB14 have ability to inhibit 5 pathogenic bacteria growth (showed by inhibition zone). Identification based on 16S rRNA gene showed that both isolates possibly are Pseudomonas sp. KR 1.13.
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Judul: Identifikasi Cendawan Endofit Asal Tanaman Obat dan Penapisan Potensinya sebagai Antibakteri
Abstrak: Endophytic fungi are microorganisms living in plant tissue without causing any harm to its host. The fungi can be found in all plants including medicinal plants. Endophytic fungi produced variety of bioactive compounds such as antibacterial substances. This research aimed to identify 3 isolates of endophytic fungi JBa8, JMa3, and SLbt3 which were isolated from medicinal plants and to screen their potency as source of antibacterial compounds. Identification of endophytic fungi was performed based on morphological characteristics and DNA barcode using ITS region. Antibacterial test was conducted against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Enteropathogenic Escherichia coli (EPEC) K1-1, and microflora E. coli by antagonism technique and agar diffusion method using mycelia extract with methanol solvent. The inhibition activity of fungal extract on bacterial tested was observed on the day 3rd, 7th, 10th, and 14th after incubation by measuring clear zone around the colonies. The 3 isolates were tentatively identified as Fusarium solani for JBa8, Fusarium sp. for JMa3, and Colletotrichum sp. for SLbt3. Antibacterial activities were observed in F. solani and Fusarium sp. which were isolated from jati belanda (Guazuma ulmifolia) and jahe merah (Zingiber officinale), respectively. F. solani inhibited the growth of EPEC K1-1, whereas Fusarium sp. suppressed P. aeruginosa with clear zone produced was 12 mm. Fusarium sp. had antibacterial activity similar with that of 8 μg/mL cefotaxime positive control. The F. solani antibacterial activity, however, was lower than the two positive control concentrations used. Colletotrichum sp. isolated from sambiloto (Andrographis paniculata) did not have any antibacterial to all bacteria tested.
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Judul: Simulasi Numerik Model Arus Lalu Lintas Satu Arah Berbasis Fungsi Velositas Underwood
Abstrak: Mobilitas masyarakat yang meningkat beberapa tahun terakhir memberikan dampak yang linier terhadap jumlah kendaraan pribadi dan angkutan umum. Jumlah kendaraan yang meningkat seringkali tidak seiring dengan penambahan kapasitas jalan raya. Jumlah kendaraan yang melebihi kapasitas jalan raya pada waktu-waktu tertentu adalah salah satu penyebab kemacetan. Beberapa matematikawan menggambarkan fenomena kepadatan lalu lintas dalam bentuk model matematika untuk membantu mengurangi masalah kemacetan yang disebabkan oleh jumlah kendaraan yang melebihi kapasitas jalan. Model matematika arus lalu lintas pertama kali dikembangkan pada tahun 1955 oleh James Lighthill, Gerald B. Whitham dan Richard P. yang dikenal sebagai model LWR. Model ini menggambarkan fenomena lalu lintas yang dihasilkan dari interaksi banyak kendaraan dengan variabel dasar lalu lintas seperti kepadatan, kecepatan dan aliran kendaraan dan dapat digunakan untuk memprediksi fenomena kepadatan arus lalu lintas kedepannya. Dalam model LWR, fungsi velositas ( rata-rata kecepatan yg diukur dalam satuan jarak persatuan waktu) merupakan elemen yang paling penting dalam menentukan kecocokan model. Penelitian ini menggunakan fungsi velositas Underwood yang berbentuk fungsi ekponensial. Model LWR berbasis fungsi velositas Underwood diselesaikan secara numerik karena nilai awal dari kepadatan kendaraan tidak berbentuk fungsi sederhana, sehingga solusi analitik dari model LWR berbasis fungsi velositas Underwood sulit ditemukan. Penyelesaian secara numerik menggunakan metode beda hingga skema implisit yang telah terbukti konvergen. Simulasi numerik dilakukan untuk menggambarkan fenomena kepadatan arus lalu lintas. Simulasi numerik pada penelitian ini dilakukan dengan 2 parameter yang berbeda. Hasil simulasi numerik menunjukkan kecenderungan perubahan arus lalu lintas jika data diubah-ubah.
Keyword: Model LWR, Fungsi Velositas Underwood, Metode beda hingga Implisit, Simulasi Numerik