Effect of carbon dioxide on fruiting in Aspergillus nidulans

Abstract

The effect of carbon dioxide concentration on growth and sexual differentiation of Aspergillus nidulans was investigated. The activities of several enzymes of intermediary carbon metabolism were only slightly affected by removal of carbon dioxide. However, depending on the time and duration of a lowered carbon dioxide level, sexual differentiation was strongly inhibited, possibly through inhibition of α-1,3 glucan synthesis. If the cultures were deprived of carbon dioxide at the end of the growth phase, the activity of the developmentally regulated enzyme α-1,3 glucanase was very low and sexual differentiation was inhibited. Addition of carbon compounds to the medium in some cases alleviated the negative effect of lack of CO₂ on sexual differentiation. A concentration of carbon dioxide higher than the atmospheric concentration is important in Aspergillus nidulans for α-1,3 glucan metabolism and sexual differentiation.