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: Identifikasi Cendawan Endofit Asal Tanaman Obat Jati Belanda (Guazuma ulmifolia) serta Penapisan Potensi Antibakterinya
Abstrak: Endophytic fungi are microorganisms living in healthy tissue of their host plants without causing disease. Endophytic fungi live in every plant, including jati belanda medicinal plant intracellulary and/or intercellulary. Jati belanda (Guazuma ulmifolia) is one of Indonesia medicinal plants. The plant produced antimicrobe substances, including antibacteria. This research aimed to identify three endophytic fungi isolated from jati belanda morphologically and molecularly, and to screen their antibacterial potency by using mycelial extracts obtained with methanol solvent against microflora Escherichia coli, Enteropathogenic Escherichia coli (EPEC) K1-1, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis as tested bacteria. The three endophytic fungi were JBba3, JBba4, and JBa5. Based on morphological characteristics, fungal isolate JBba3 identified as Rhizopycnis sp.1, JBa5 was Rhizopycnis sp.2, whereas JBba4 was Colletotrichum sp. Identification results by using ITS rDNA region showed that isolates JBba3 and JBa5 were Rhizopycnis vagum, meanwhile isolate JBba4 was Colletotrichum sp. All three isolates tested did not inhibit the growth of the microflora E. coli. Isolates Rhizopycnis sp.1 and Rhizopycnis sp.2 did not inhibit the growth of all bacteria tested. Isolate Colletotrichum sp. inhibited the growth of EPEC K1-1 and P. aeruginosa with diameters zone of inhibition were 13.0 and 6.7 mm, respectively. Antibacterial potencies of Colletotrichum sp. mycelial extract were similar with cefotaxime antibiotic as positive control on two concentrations tested, which were 8 and 64 μg/ml.
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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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