
Full text loading...
Summary: The rate of carbon dioxide fixation by Fusarium culmorum during vegetative growth in glucose-limited continuous culture at pH 3·5 was 0·036 μmol CO2 fixed (mg hyphae)−1 h−1; during conidium production at pH 6·5 it reached a maximum value of 0·29 μmol CO2 fixed (mg hyphae)−1 h−1. During growth in phosphate-limited continuous cultures, containing sufficient glucose to suppress conidiation, the rate of CO2 fixation was 0·045 μmol CO2 fixed (mg hyphae)−1 h−1, and did not increase substantially following an increase in pH to 6·5. The internal hyphal pH remained at approximately 6·5 despite changes in the external pH from 3·5 to 6·5. Phosphoenolpyruvate carboxykinase (EC 4.1.1.32) and pyruvate carboxylase (EC 6.4.1.1) activities estimated in hyphal extracts gave a fixation rate approximately three times the rate of CO2 fixation in vivo in glucose-limited and phosphate-limited vegetative continuous cultures at pH 3·5. In conidiating cultures, phosphoenolpyruvate carboxykinase and pyruvate carboxylase activities approximately equalled the highest CO2 fixation rates in vivo. Fixed 14C was distributed amongst all the major cell components, with the highest percentage in the conidial protein fraction.
Article metrics loading...
Full text loading...
References
Data & Media loading...