Person: González Jaén, María Teresa
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First Name
María Teresa
Last Name
González Jaén
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Biológicas
Department
Genética, Fisiología y Microbiología
Area
Genética
Identifiers
7 results
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Now showing 1 - 7 of 7
Item Description of an orthologous cluster of ochratoxin A biosynthetic genes in Aspergillus and Penicillium species. A comparative analysis(International Journal of Food Microbiology, 2018) Gil-Serna, Jessica; García-Díaz, Marta; González Jaén, María Teresa; Vázquez Estevez, Covandonga; Patiño Álvarez, BelénOchratoxin A (OTA) is one of the most important mycotoxins due to its toxic properties and worldwide distribution which is produced by several Aspergillus and Penicillium species. The knowledge of OTA biosynthetic genes and understanding of the mechanisms involved in their regulation are essential. In this work, we obtained a clear picture of biosynthetic genes organization in the main OTA-producing Aspergillus and Penicillium species (A. steynii, A. westerdijkiae, A. niger, A. carbonarius and P. nordicum) using complete genome sequences obtained in this work or previously available on databases. The results revealed a region containing five ORFs which predicted five proteins: halogenase, bZIP transcription factor, cytochrome P450 monooxygenase, non-ribosomal peptide synthetase and polyketide synthase in all the five species. Genetic synteny was conserved in both Penicillium and Aspergillus species although genomic location seemed to be different since the clusters presented different flanking regions (except for A. steynii and A. westerdijkiae); these observations support the hypothesis of the orthology of this genomic region and that it might have been acquired by horizontal transfer. New real-time RT-PCR assays for quantification of the expression of these OTA biosynthetic genes were developed. In all species, the five genes were consistently expressed in OTA-producing strains in permissive conditions. These protocols might favour futures studies on the regulation of biosynthetic genes in order to develop new efficient control methods to avoid OTA entering the food chain.Item Targeting conserved genes in fusarium species(Mycotoxigenic Fungi: Methods and Protocols, 2017) Gil-Serna, Jessica; Patiño Álvarez, Aurora Belén; Jurado, Miguel; Mirete Castañeda, Salvador; Vázquez Estévez, Covadoga; González Jaén, María TeresaFumonisins are important mycotoxins contaminating foods and feeds which are mainly produced by F. verticillioides and F. proliferatum. Additionally, both are pathogens of maize and other cereals. We describe two highly sensitive, rapid, and species-specific PCR protocols which enable detection and discrimination of these closely related species in cereal flour or grain samples. The specific primer pairs of these assays were based on the intergenic spacer region of the multicopy rDNA unit which highly improves the sensitivity of the PCR assay in comparison with single-copy target regions.Item Evaluation of growth and ochratoxin A production by Aspergillus steynii and Aspergillus westerdijkiae in green-coffee based medium under different environmental conditions(Food research international, 2014) Gil-Serna, Jessica; Vázquez Estévez, Covadoga; García Sandino, Fernando; Márquez Valle, Ana; González Jaén, María Teresa; Patiño Álvarez, BelénAspergillus steynii and Aspergillus westerdijkiae are important ochratoxin A (OTA)-producing species frequently found in coffee. Although the processing of green coffee beans reduces markedly OTA contamination, levels exceeding the legal limitsmight remain in the final product. Environmental conditions are a crucial factor affecting growth and OTA production in fungal species; therefore, in thiswork,we analysed the effect of different levels of temperature (23, 28, 32, 37, 42 °C) andwater activity (aw) (0.89, 0.91, 0.93, 0.95, 0.97, 0.99) on growth and toxin production by A. steynii and A. westerdijkiae in green coffee-based medium. A. steynii was able to grow and produce OTA in a wider set of conditions than A. westerdijkiae. A new index (OTA risk index) has been described to integrate both fungal growth and OTA production and, according to it, A. steynii would pose a higher risk of OTA contamination in coffee than A. westerdijkiae at all the conditions tested. Neither A. steynii nor A. westerdijkiae were able to grow at the lowest value of aw (0.89) evaluated and OTA production was extremely low at 0.91. Therefore, the application of good practices during storage aiming to maintain low humidity levelsmight be essential to prevent OTA contamination in coffee at this stage. The optimal conditions of both species to grow and produce OTA were established at warm temperatures (28–32 °C) and high aw levels. Therefore, these species could be considered well-adapted in predicted climate change scenarios resulting in a potential high risk source of OTA contamination for this product.Item Métodos alternativos al control químico de hongos toxígenos y micotoxinas en alimentos(ANS. Alimentación nutrición y salud, 2014) Gil-Serna, Jessica; Patiño Álvarez, Belén; Vázquez Estévez, Covadoga; González Jaén, María TeresaLas micotoxinas son un grave riesgo para la seguridad alimentaria y es imprescindible controlar su presencia en alimentos. Tradicionalmente, se han aplicado compuestos químicos para evitar el desarrollo de los hongos productores aunque, en los últimos años, se ha restringido mucho su uso debido a los problemas que ocasionan para la salud y el medio ambiente y a la restrictiva legislación Europea. En este trabajo, se ha evaluado la efectividad in vitro de métodos alternativos (antioxidantes, aceites esenciales y control biológico con microorganismos antagónicos) para controlar el crecimiento y la producción de micotoxinas de importantes especies del género Aspergillus. Los extractos de salvia española y espliego, así como el agente biológico Debaryomyces hansenii CYC 1244 han demostrado ser prometedores candidatos para la reducción de la contaminación por micotoxinas en alimentos al ser capaces de reducir significativamente el desarrollo y la producción de micotoxinas en varias de especies toxígenas.Item Significance of Aspergillus nigeraggregate species as contaminants of food products in Spain regarding their occurrence and their ability to produce mycotoxins(Food Microbiology, 2019) Gil-Serna, Jessica; García-Díaz, Marta; Vázquez, Covadonga; González Jaén, María Teresa; Patiño Álvarez, BelénThe Aspergillus niger aggregate contains 15 morphologically indistinguishable species which presence is related to ochratoxin A (OTA) and fumonisin B2 (FB2) contamination of foodstuffs. The taxonomy of this group was recently reevaluated and there is a need of new studies regarding the risk that these species might pose to food security. 258 isolates of A. niger aggregate obtained from a variety of products from Spain were classified by molecular methods being A. tubingensis the most frequently occurring (67.5%) followed by A. welwitschiae (19.4%) and A. niger (11.7%). Their potential ability to produce mycotoxins was evaluated by PCR protocols which allow a rapid detection of OTA and FB2 biosynthetic genes in their genomes. OTA production is not widespread in A. niger aggregate since only 17% of A. niger and 6% of A. welwitschiae isolates presented the complete biosynthetic cluster whereas the lack of the cluster was confirmed in all A. tubingensis isolates. On the other hand, A. niger and A. welwitschiae seem to be important FB2 producers with 97% and 29% of the isolates, respectively, presenting the complete cluster. The genes involved in OTA and FB2 were overexpressed in producing isolates and their expression was related to mycotoxin synthesis.Item Aspergillus steynii and Aspergillus westerdijkiae as potential risk of OTA contamination in food products in warm climates(Food microbiology, 2014) Gil-Serna, Jessica; Patiño Álvarez, Belén; Cortes, Laura; González Jaén, María Teresa; Vázquez Estévez, CovadogaAspergillus steynii and Aspergillus westerdijkiae are the main ochratoxin A (OTA) producing species of Aspergillus section Circumdati. Due to its recent description, few data are available about the influence of cophysiological factors on their growth and OTA production profiles. In this work, the effect of temperature (20, 24 and 28ºC) and water activity (aw) (0.928, 0.964 and 0.995) on rowth, sporulation and OTA production by these fungi was examined in CYA and media prepared from paprika, green coffee, anise, grapes, maize and barley. Growth was positively affected by the highest temperature and aw values indicating that both species might be expected in warm climates or storage conditions. However, optimal growth conditions showed differences depending on the medium. OTA production was markedly affected by substrate and showed qualitative and quantitative differences. Both species, especially A. steynii, represent a great potential risk of OTA contamination due to their high production in a variety of conditions and substrates, in particular in barley and paprika-based media. Additionally, neither growth nor sporulation did result good indicators of OTA production by A. steynii or A. westerdijkiae;therefore, specific and highly-sensitive detection methods become essential tools for control strategies to reduce OTA risk by these species.Item Evaluating aflatoxin gene expression in aspergillus section flavi(Mycotoxigenic Fungi, 2017) Azevedo Rodrigues, Paula Cristina; Gil-Serna, Jessica; González Jaén, María TeresaThe determination of aflatoxin production ability and differentiation of aflatoxigenic strains can be assessed by monitoring the expression of one or several key genes using reverse transcription polymerase chain reaction (RT-PCR). We herein describe the methods for RNA induction, extraction, and quality determination, and the RT-PCR conditions used to evaluate the ability of a given Aspergillus strain to produce aflatoxins.