Resumen: La bioluminiscencia es la capacidad de emisión de luz que presentan ciertos organismos, ... more Resumen: La bioluminiscencia es la capacidad de emisión de luz que presentan ciertos organismos, una característica que también está presente en algunas bacterias. En este trabajo se explican las características bioquímicas, moleculares, ecológicas y las aplicaciones de la bioluminiscencia bacteriana. Esta información proporciona la base teórica para el desarrollo de una propuesta práctica que pone de manifiesto la capacidad de emisión de luz y su dependecia de factores como el oxígeno. Palabras clave: Bioluminiscencia. Luciferasa. Vibrio harveyi. Quorum sensing. Genes lux. INTRODUCCIÓN A LA BIOLUMINISCENCIA BACTERIANA En los seres vivos, la emisión de luz puede ser de dos tipos; (i) fotoluminiscencia (fosforescencia y fluorescencia), debida a la presencia de moléculas fotoexcitables que absorben luz a una determinada longitud de onda y la emiten a una longitud de onda mayor (h ') y (ii) la quimioluminiscencia, que en organismos vivos recibe el nombre de bioluminiscencia, en la ...
Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. Th... more Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. These mycotoxins are mainly produced by Aspergillus flavus and Aspergillus parasiticus, two closely related species with different array of aflatoxins. In this work, two specific quantitative PCR (qPCR) assays were developed to detect and quantify both species in wheat flour using primers based on the multicopy ITS2 rDNA target sequence. The species specificity of the assays was tested in a wide range of strains of these species and others colonizing the same commodities. The sensitivity of the assay was estimated in 2.5 pg/reaction in both species. Discrimination capacity for detection and relative quantification of A. flavus and A. parasiticus DNA were analyzed using samples with DNA mixtures containing also other fungal species at different ratios. Both qPCR assays could detect spore concentrations equal or higher than 10 6 spores/g in flour samples without prior incubation. These assays are valuable tools to improve diagnosis at an early stage and in all critical control points of food chain integrated in HACCP strategies.
Two PCR assays have been developed to detect Aspergillus carbonarius and Aspergillus ochraceus, c... more Two PCR assays have been developed to detect Aspergillus carbonarius and Aspergillus ochraceus, considered the main sources of ochratoxin A (OTA) contaminating commodities, particularly grapes, coffee and derivatives, in warm climates. The species specific primers have been designed on the basis of ITS (internal transcribed spacers of rDNA units) sequence comparisons obtained from Aspergillus strains and have been tested in a number of strains from different origins and hosts. These PCR assays, based on multi-copy sequences, are highly sensitive and specific and represent a good tool for an early detection of OTA-producing Aspergillus species and to prevent OTA entering the food chain. D
Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. Th... more Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. These mycotoxins are mainly produced by Aspergillus flavus and Aspergillus parasiticus, two closely related species with different array of aflatoxins. In this work, two specific quantitative PCR (qPCR) assays were developed to detect and quantify both species in wheat flour using primers based on the multicopy ITS2 rDNA target sequence. The species specificity of the assays was tested in a wide range of strains of these species and others colonizing the same commodities. The sensitivity of the assay was estimated in 2.5 pg/reaction in both species. Discrimination capacity for detection and relative quantification of A. flavus and A. parasiticus DNA were analyzed using samples with DNA mixtures containing also other fungal species at different ratios. Both qPCR assays could detect spore concentrations equal or higher than 10 6 spores/g in flour samples without prior incubation. These assays are valuable tools to improve diagnosis at an early stage and in all critical control points of food chain integrated in HACCP strategies.
An antifungal polypeptide (AFP) of 51 amino acid residues, secreted by the mould Aspergillus giga... more An antifungal polypeptide (AFP) of 51 amino acid residues, secreted by the mould Aspergillus giganteus, has been purified to homogeneity and characterized. The inhibitory effect of this protein on the growth of different microorganisms has been studied. Whereas
ABSTRACT An isolate of Aspergillus fumigatus, present at high frequency in compost samples from s... more ABSTRACT An isolate of Aspergillus fumigatus, present at high frequency in compost samples from sewage sludge from Madrid, was analysed for tolerance and adaptation to copper. Although high copper concentrations (350 mg 1−1) inhibited fungal growth, training the fungus by successive sub-culturing in media containing progressively higher copper concentrations resulted in the fungus being able to grow in a medium containing 50 mg l−1 more copper than when it was not trained. Changes in some morphological features were also observed following training. Copper negatively affected two parameters of fungal growth, specific growth rate (μ) and lag-phase. Protein patterns obtained by SDS-PAGE of control and copper-amended cultures of A. fumigatus were compared and one protein of 20.2 kDa appeared to be specifically associated with the presence of copper in cultures.
Resumen: La bioluminiscencia es la capacidad de emisión de luz que presentan ciertos organismos, ... more Resumen: La bioluminiscencia es la capacidad de emisión de luz que presentan ciertos organismos, una característica que también está presente en algunas bacterias. En este trabajo se explican las características bioquímicas, moleculares, ecológicas y las aplicaciones de la bioluminiscencia bacteriana. Esta información proporciona la base teórica para el desarrollo de una propuesta práctica que pone de manifiesto la capacidad de emisión de luz y su dependecia de factores como el oxígeno. Palabras clave: Bioluminiscencia. Luciferasa. Vibrio harveyi. Quorum sensing. Genes lux. INTRODUCCIÓN A LA BIOLUMINISCENCIA BACTERIANA En los seres vivos, la emisión de luz puede ser de dos tipos; (i) fotoluminiscencia (fosforescencia y fluorescencia), debida a la presencia de moléculas fotoexcitables que absorben luz a una determinada longitud de onda y la emiten a una longitud de onda mayor (h ') y (ii) la quimioluminiscencia, que en organismos vivos recibe el nombre de bioluminiscencia, en la ...
Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. Th... more Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. These mycotoxins are mainly produced by Aspergillus flavus and Aspergillus parasiticus, two closely related species with different array of aflatoxins. In this work, two specific quantitative PCR (qPCR) assays were developed to detect and quantify both species in wheat flour using primers based on the multicopy ITS2 rDNA target sequence. The species specificity of the assays was tested in a wide range of strains of these species and others colonizing the same commodities. The sensitivity of the assay was estimated in 2.5 pg/reaction in both species. Discrimination capacity for detection and relative quantification of A. flavus and A. parasiticus DNA were analyzed using samples with DNA mixtures containing also other fungal species at different ratios. Both qPCR assays could detect spore concentrations equal or higher than 10 6 spores/g in flour samples without prior incubation. These assays are valuable tools to improve diagnosis at an early stage and in all critical control points of food chain integrated in HACCP strategies.
Two PCR assays have been developed to detect Aspergillus carbonarius and Aspergillus ochraceus, c... more Two PCR assays have been developed to detect Aspergillus carbonarius and Aspergillus ochraceus, considered the main sources of ochratoxin A (OTA) contaminating commodities, particularly grapes, coffee and derivatives, in warm climates. The species specific primers have been designed on the basis of ITS (internal transcribed spacers of rDNA units) sequence comparisons obtained from Aspergillus strains and have been tested in a number of strains from different origins and hosts. These PCR assays, based on multi-copy sequences, are highly sensitive and specific and represent a good tool for an early detection of OTA-producing Aspergillus species and to prevent OTA entering the food chain. D
Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. Th... more Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. These mycotoxins are mainly produced by Aspergillus flavus and Aspergillus parasiticus, two closely related species with different array of aflatoxins. In this work, two specific quantitative PCR (qPCR) assays were developed to detect and quantify both species in wheat flour using primers based on the multicopy ITS2 rDNA target sequence. The species specificity of the assays was tested in a wide range of strains of these species and others colonizing the same commodities. The sensitivity of the assay was estimated in 2.5 pg/reaction in both species. Discrimination capacity for detection and relative quantification of A. flavus and A. parasiticus DNA were analyzed using samples with DNA mixtures containing also other fungal species at different ratios. Both qPCR assays could detect spore concentrations equal or higher than 10 6 spores/g in flour samples without prior incubation. These assays are valuable tools to improve diagnosis at an early stage and in all critical control points of food chain integrated in HACCP strategies.
An antifungal polypeptide (AFP) of 51 amino acid residues, secreted by the mould Aspergillus giga... more An antifungal polypeptide (AFP) of 51 amino acid residues, secreted by the mould Aspergillus giganteus, has been purified to homogeneity and characterized. The inhibitory effect of this protein on the growth of different microorganisms has been studied. Whereas
ABSTRACT An isolate of Aspergillus fumigatus, present at high frequency in compost samples from s... more ABSTRACT An isolate of Aspergillus fumigatus, present at high frequency in compost samples from sewage sludge from Madrid, was analysed for tolerance and adaptation to copper. Although high copper concentrations (350 mg 1−1) inhibited fungal growth, training the fungus by successive sub-culturing in media containing progressively higher copper concentrations resulted in the fungus being able to grow in a medium containing 50 mg l−1 more copper than when it was not trained. Changes in some morphological features were also observed following training. Copper negatively affected two parameters of fungal growth, specific growth rate (μ) and lag-phase. Protein patterns obtained by SDS-PAGE of control and copper-amended cultures of A. fumigatus were compared and one protein of 20.2 kDa appeared to be specifically associated with the presence of copper in cultures.
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