Selection and characterization of Aspergillus nidulans mutants involved in regulation of glycerol metabolism

Pathway-specific induction plays an important role in Aspergiffus nidufans when this fungus is grown on media containing glycerol as carbon source. To obtain mutants altered in regulation of glycerol metabolism, we used a gfcB mutant strain, which is unable to grow on mixed carbon sources like D-glucose/glycerol as it accumulates G3P. Pseudorevertants, derived from this strain after mutagenesis as able to grow on D-glucose/glycerol, were analysed. In addition to glycerol kinase mutants and glycerol uptake mutants four new classes of mutants were found. Biochemical and genetic data indicate that the gfcH mutants found are likely to lack a positive factor necessary for full induction of glycerol kinase and glycerol-3-phosphate dehydrogenase activities. The phenotype of a temperature-sensitive gfcl mutant was found to be influenced by oxygen tension. Elevated levels of intracellular phosphatase were found in a gfcL mutant. The gfcKl mutant had slow growth rates and higher levels of phosphofructokinase and fructose-&phosphate reductase