D-Galactose uptake is nonfunctional in the conidiospores of Aspergillus niger.
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.
Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.
Erzsébet
E
Fekete
Ronald P
RP
de Vries
Bernhard
B
Seiboth
Patricia A
PA
vanKuyk
Erzsébet
E
Sándor
Eva
E
Fekete
Benjamin
B
Metz
Christian P
CP
Kubicek
Levente
L
Karaffa
D001234:Aspergillus niger / Q000378:metabolism*; D005285:Fermentation; D005690:Galactose / Q000378:metabolism*; D006019:Glycolysis; D053858:Metabolic Networks and Pathways; D010641:Phenotype; D010766:Phosphorylation; D015203:Reproducibility of Results; D013172:Spores, Fungal / Q000378:metabolism
D005690:Galactose