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
5 results
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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 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 Phylogenetic analysis and growth profiles of Fusarium incarnatum-equiseti species complex strains isolated from Tunisian cereals(International Journal of Food Microbiology, 2021) Jedidi, Ines; Jurado, Miguel; Cruz, Alejandra; Mounir, Mohamed Trabelsi; Said, Salem; González Jaén, María TeresaThe Fusarium incarnatum-equiseti species complex (FIESC) is a phylogenetically rich complex. It includes more than 30 cryptic phylogenetic species, making morphological identification problematic. FIESC has previously been detected in Tunisian cereals, but knowledge on the phylogeny and the ecophysiology of their species is lacking. In this work a phylogenetic analysis was performed using partial sequences of the translation elongation factor 1a gene (EF1a) of three FIESC strains isolated from barley and wheat from Tunisia, situated south in the Mediterranean basin, and additional strains from other countries. The results indicated that all Tunisian strains clustered with FIESC 5 group (F. clavum) together with other Spanish FIESC 5 strains also isolated from cereals. Growth rate profiles of the Tunisian strains were also determined on wheat and sorghum based media at a range of temperatures (15, 20, 25, 30, 35 and 40 ◦C) and water potential values (− 0.7, − 2.8, − 7.0, and − 9.8 MPa, corresponding to 0.995, 0.98, 0.95 and 0.93 aw values). Optimal growth was observed at 20–30 ◦C and between − 0.7 and − 7.0 MPa on both substrates (wheat and sorghum). The highest growth rate for the three strains was seen at 25 ◦C combined with − 2.8 MPa. The comparison between the growth profiles of Tunisian and Spanish FIESC 5 strains showed similar trends with some interesting differences regarding temperature and water potential factors. Tunisian strains seem to perform better between 15 and 30 ◦C and, notably, at even lower water potentials included − 9.8 Mpa. This might suggest that tolerance to low water potentials might be for Tunisian strains a more important selective clue than to higher temperatures. These results appeared to be consistent with a population well adapted to the present climatic conditions and predicted scenarios for North Africa.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.