The effects of malonate on the gaseous exchange and acid metabolism of mycelial suspensions of Aspergillus niger have been studied.
Malonate penetrated into the cells of the fungus but did not exert its normal effect as a competitive inhibitor in the TCA cycle, even at high external concentrations. On the contrary it stimulated oxidative catabohsm. Some of the malonate which penetrated was consumed by the fungus and it is inferred that the remainder was stored within the mycelium away from malonate sensitive centres in the cytoplasm.
Experiments performed with [2-14C] malonate have shown that part of the malonate molecule may be utilized in the synthesis of larger structural molecules of the mycelium. Possible pathways of malonate metabolism are discussed in the light of work carried out with other organisms.