SUMMARY: A mutant of is shown to have an absolute requirement for riboflavin when grown at 30°, but this requirement is less stringent when the organism is grown at 25°. The Fe, Cu, Zn, Mn and Mo requirements of the mutant, grown at either temperature, are similar to those of the wild type (146) so that it seems unlikely that these metals are involved in the biosynthesis of riboflavin. A study of enzyme patterns in the mutant, grown at 30° and given optimal or deficient concentrations of ribfiavin, demonstrated alternative pathways of electron transfer in the fungus. When riboflavin is deficient, the iron enzymes are markedly increased and oxygen is probably the main terminal acceptor of the electrons. At optimal concentrations of riboflavin, the flavoprotein enzymes are produced and nitrate and nitrite reductases are active so that nitrate can act as a terminal acceptor. Iron deficiency is readily produced in the mutant when riboflavin is deficient because of the increased activity of iron enzymes; a molybdenum requirement is greater at optimal riboflavin concentrations because of the enhanced production of molybdo-flavoproteins.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error