Citrate efflux in glucose-limited and glucose-sufficient chemostat culture of Penicillium simplicissium.
Citrate excretion by Penicillium simplicissimum was investigated in a chemostat. Carbon-limited grown P. simplicissimum did not excrete no citrate. Citrate was excreted, however, when growth was nitrogen-limited. Further effects of nitrogen-limitation were a slightly increased rate of glucose and oxygen consumption. This behaviour is typical for a so-called 'overflow metabolism', i.e. the uncoupling of anabolism from catabolism under conditions of carbon excess. Still more citrate was excreted by nitrogen-limited P. simplicissimum when (i) the extracellular osmolarity was increased from 0.2 to 1.5 osm kg(-1) or (ii) when the pH was increased from 4 to 7; or (iii) when the extracellular potassium concentration was lowered from 6 to 0.5 mM. These results were interpreted in terms of a higher energy-consumption under these conditions.
Gallmetzer
M
M
Institute of Microbiology, University of Innsbruck, Austria. martin.gallmetzer@uibk.ac.at
Burgstaller
W
W
D019149:Bioreactors; D002244:Carbon / Q000378:metabolism; D019343:Citric Acid / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000378:metabolism; D010407:Penicillium / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D013997:Time Factors
D019343:Citric Acid; D002244:Carbon; D005947:Glucose; D009584:Nitrogen; D011188:Potassium