Judul: Identifikasi Cendawan Endofit Asal Tanaman Obat Jati Belanda (Guazuma ulmifolia) serta Penapisan Potensi Antibakterinya
Abstrak: Cendawan endofit ialah mikroorganisme yang hidup di dalam jaringan sehat tanaman inangnya tanpa menyebabkan penyakit. Cendawan endofit tumbuh pada setiap tumbuhan, termasuk tanaman obat jati belanda secara intraseluler dan/atau interseluler. Jati belanda merupakan salah satu tanaman obat di Indonesia yang mengandung senyawa antimikroba, termasuk antibakteri. Penelitian ini bertujuan untuk mengidentifikasi tiga cendawan endofit asal jati belanda secara morfologi dan molekuler, serta menapis potensi antibakterinya menggunakan ekstrak miselia dengan pelarut metanol terhadap bakteri uji Escherichia coli flora normal, Escherichia coli Enteropatogenik (EPEC) K1-1, Staphylococcus aureus, Pseudomonas aeruginosa, dan Bacillus subtilis. Ketiga cendawan endofit tersebut ialah JBba3, JBba4, dan JBa5. Berdasarkan karakteristik morfologi, isolat JBba3 teridentifikasi sebagai Rhizopycnis sp.1, JBa5 ialah Rhizopycnis sp.2, sedangkan isolat JBba4 ialah Colletotrichum sp. Hasil identifikasi menggunakan ruas ITS rDNA menunjukkan bahwa isolat JBba3 dan JBa5 ialah Rhizopycnis vagum, sedangkan isolat JBba4 ialah Colletotrichum sp. Semua isolat tidak menghambat pertumbuhan E. coli flora normal. Isolat Rhizopycnis sp.1 dan Rhizopycnis sp.2 tidak menghambat pertumbuhan semua bakteri uji. Isolat Colletotrichum sp. menghambat pertumbuhan bakteri EPEC K1-1 dan P. aeruginosa dengan rata-rata diameter zona hambat masing-masing sebesar 13.0 dan 6.7 mm. Kemampuan antibakteri dari ekstrak miselia dengan pelaut metanol isolat Colletotrichum sp. sama dengan antibiotik cefotaxime sebagai kontrol positif pada dua konsentrasi yang diuji, yaitu 8 dan 64 μg/ml.
Keyword: Bogor Agricultural University, Institut Pertanian Bogor, IPB

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: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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