Published online by Cambridge University Press: 14 April 2009
Using polarography the uptake of oxygen by intact and homogenized mycelium of a wild-type strain and strains of slow-growing non-perithecial (sgp) mutants was compared. It was found that whilst the oxygen uptake of intact, wild-type mycelium increased on the addition of glucose or succinate as substrate, uptake of oxygen by mutant mycelium increased only when glucose was used as substrate and was unaffected by succinate. When, however, homogenates of mutant mycelium were used oxidation of the succinate occurred. It was concluded that the inability of the mutants to utilize succinate was due to their impaired ability to take up the compound across the hyphal wall and this was confirmed using radioactively labelled substrates. It is tentatively suggested that the abnormal growth of the sgp mutants on glucose medium and their impaired permeability to tricarboxylic acid cycle intermediates may be due to reduced availability of high energy compounds caused by a lesion in their oxidative phos-phorylation system.