Examinando por Autor "Estrada, Juan"

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    Ítem
    Microdot method: used with chromogenic agar is a useful procedure for sanitary monitoring in aquaculture
    (UNIVERSIDAD CATOLICA DE VALPARAISO, 2016-09) Strahsburger, Erwin; Retamales, Patricio; Estrada, Juan; Seeger, Michael
    The microdot method is a downscaling methodology of traditional tenfold serial dilution procedure used in microbiology. The microdot method uses 100 mu L for serial dilution and count colonies in a spot of 10 mu L. In this study we counted colonies directly in a chromogenic agar plate to determine, at the same time, the presence and cell concentration of target bacteria required for sanitary monitoring of Chilean export fishery products. Due to among importers countries the most concerning bacteria included in sanitary monitoring are Escherichia coli, Listeria monocytogenes and Staphylococcus aureus, we used the chromogenic agar; CHROMagar ECC, CHROMagar Listeria and Baird Parker agar, respectively. The results shows no differences between quantitative results obtained with microdot and traditional method during the quantification of a culture of Escherichia coli (1.5 L). The sensitivity and specificity of the microdot method in association with each chromogenic agar was demonstrated in vitro with reference strains. In addition, the usefulness in sanitary monitoring of aquaculture procedures was evaluated in Artemia salina tanks. This method did not detected sanitary problems in surface water. Although other colonies grown in the chromogenic agar plate, their morphological and chromogenic properties not correspond to Escherichia coli, Listeria monocytogenes and Staphylococcus aureus, being identified as Salmonella enterica subsp. enterica, Microbacterium sp., Bacillus sp. and Staphylococcus pasteuri by 16S rRNA gene sequence analysis. Hence, we propose the microdot chromogenic method as a low cost, specific and reliable procedure for sanitary monitoring of aquaculture procedures.
  • Miniatura
    Ítem
    Nuclear DNA content in the red conger eel Genypterus chilensis (Guichenot, 1881) (Actinopterygii: Ophidiidae)
    (Universidad de Concepción, 2011) Jara-Seguel, Pedro; Ubilla, Andrea; Estrada, Juan; Ramírez, Diego; Valdebenito, Iván
    Studies about nuclear DNA content in the genus Genypterus are scarce, and the present study gives the first estimate of nuclear DNA content of Genypterus chilensis, with a value of 2C= 1.0 + 0.06 pg, value close to that obtained for other Ophidiidae species wich range between 1.2 and 1.68 pg.