Doralinda A. Guzmán-de-Peña

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Regulation of aflatoxin biosynthesis during differentiation of Aspergillus parasiticus was analyzed by using a drug that inhibits the development of the fungus and mutants affected in sporulation. Diaminobutanone, a competitive inhibitor of ornithine decarboxylase, repressed spore germination. If added after spore germination had occurred, it blocked(More)
AIMS To assess the ability of five probiotic bacteria to bind aflatoxin B(1) and to determine the key role of teichoic acids in the binding mechanism. METHODS AND RESULTS The strains were incubated in aqueous solutions containing aflatoxin B(1) (AFB(1)). The amount of free toxin was quantified by HPLC. Stability of the bacteria-aflatoxin complex was(More)
We analyzed the regulation of sterigmatocystin biosynthesis in wild type and mutant strains of Emericella nidulans (= Aspergillus nidulans). A positive correlation between both asexual and sexual sporulation and synthesis of the mycotoxin was observed. Those conditions which favored sporulation stimulated sterigmatocystin formation, and vice versa. Both(More)
Aflatoxins are potent mutagenic and carcinogenic compounds produced by some strains of Aspergillus flavus, A. nomius, and A. parasiticus that are commonly present in the environment. Human populations, particularly those whose basic diet includes grains, are in risk to exposure to aflatoxins. It is thus necessary to monitor and control the contamination of(More)
Aflatoxin contamination of corn is an important problem internationally, particularly in tropical and subtropical conditions that favor infection and synthesis by Aspergillus. Environmental conditions (drought) and agronomic practices i.e. N fertilization have been reported as favorable to aflatoxin synthesis in the field. This study was undertaken to(More)
Deletion of the spermidine synthase gene in the fungus Aspergillus nidulans results in a strain, deltaspdA, which requires spermidine for growth and accumulates putrescine as the sole polyamine. Vegetative growth but not sporulation or sterigmatocystin production is observed when deltaspdA is grown on media supplemented with 0.05-0.10 mM exogenous(More)
In previous communications the essential role of spermidine in Ustilago maydis was demonstrated by means of the disruption of the genes encoding ornithine decarboxylase (ODC) and spermidine synthase (SPE). However, the assignation of specific roles to each polyamine in different cellular functions was not possible because the spermidine added to satisfy the(More)
Fusarium proliferatum, F. subglutinans, and F. verticillioides are known causes of ear and kernel rot in maize worldwide. In Mexico, only F. verticillioides and F. subglutinans, have been reported previously as causal agents of this disease. However, Fusarium isolates with different morphological characteristics to the species that are known to cause this(More)
External pH constitutes one of the most important environmental factors that control growth, metabolism and differentiation in microorganisms, including fungi. We have analyzed the effect of external pH on sterigmatocystin biosynthesis in Aspergillus nidulans. It was observed in repeated experiments that alkaline pH, in opposition to acid pH, increased(More)