D-Galactose uptake is nonfunctional in the conidiospores of Aspergillus niger.

Erzsébet Fekete, Ronald P de Vries, Bernhard Seiboth, Patricia A vanKuyk, Erzsébet Sándor, Eva Fekete, Benjamin Metz, Christian P Kubicek, Levente Karaffa

Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.

FEMS microbiology letters 2012 Apr

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The majority of black Aspergilli (Aspergillus section Nigri), including Aspergillus niger, as well as many other Ascomycetes fail to germinate on d-galactose as a sole carbon source. Here, we provide evidence that the ability of A. niger to transport D-galactose is growth stage dependent, being absent in the conidiospores but present in the mycelia. Despite earlier claims, we could identify galactokinase activity in growing cells and all genes of the Leloir pathway (responsible for channelling D-galactose into the EMP pathway) are well induced on D-galactose (and also on lactose, D-xylose and L-arabinose) in the mycelial stage. Expression of all Leloir pathway genes was also detectable in conidiospores, although galE (encoding a galactokinase) and galD (encoding a galactose-1-phosphate uridylyl transferase) were expressed poorly. These results suggest that the D-galactose-negative phenotype of A. niger conidiospores may be due to the lack of inducer uptake. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Citation

Erzsébet Fekete, Ronald P de Vries, Bernhard Seiboth, Patricia A vanKuyk, Erzsébet Sándor, Eva Fekete, Benjamin Metz, Christian P Kubicek, Levente Karaffa. D-Galactose uptake is nonfunctional in the conidiospores of Aspergillus niger. FEMS microbiology letters. 2012 Apr;329(2):198-203