Culture conditions for zinc- and pH-regulated gene expression studies in Aspergillus fumigatus Authors Miguel A. Moreno Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Jorge Amich Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Rocío Vicentefranqueira Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Fernando Leal Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain José A. Calera Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Keywords: Aspergillus fumigatus, nitrogen sources, pH variations, zinc availability Abstract In Aspergillus fumigatus, the regulation of zinc homeostasis is strongly influenced by environmental pH. Thus, the study of zinc-regulated gene expression in A. fumigatus requires controlling variations in culture pH, as this may affect zinc availability. However, depending on the nitrogen source, the pH of the culture can change dramatically over time. In addition, due to the ubiquitous distribution of zinc and that it is an essential micronutrient required in minute amounts for optimal fungal growth, neither buffering of the culture media to prevent pH variations nor the use of chelating agents is advisable if mycelium is to be used for expression analyses. In this work, the growth of A. fumigatus in several culture media was examined in order to determine the conditions yielding mycelia suitable for gene expression analyses in acid and neutral media, regardless of zinc availability. Our results showed that a zinc-limiting synthetic basal medium could be readily converted into a zinc-replete one and subsequently into acid or neutral medium by using, respectively, ammonium or nitrate as nitrogen source. [Int Microbiol 2007; 10(3):187-192] Author Biographies Miguel A. Moreno, Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Jorge Amich, Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Rocío Vicentefranqueira, Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Fernando Leal, Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain José A. Calera, Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Institute of Microbiology-Biochemistry, Department of Microbiology and Genetics, University of Salamanca-CSIC, Salamanca, Spain Downloads PDF Published 2010-01-22 Issue Vol. 10 No. 3 (2007) Section Research Articles License Submission of a manuscript to International Microbiology implies: that the work described has not been published before, including publication in the World Wide Web (except in the form of an Abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that all the coauthors have agreed to its publication. 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