Growth and metabolism of Saccharomyces cerevisiae in chemostat cultures under carbon-, nitrogen-, or carbon- and nitrogen-limiting conditions.
AUTOR(ES)
Larsson, C
RESUMO
Aerobic chemostat cultures of Saccharomyces cerevisiae were performed under carbon-, nitrogen-, and dual carbon- and nitrogen-limiting conditions. The glucose concentration was kept constant, whereas the ammonium concentration was varied among different experiments and different dilution rates. It was found that both glucose and ammonium were consumed at the maximal possible rate, i.e., the feed rate, over a range of medium C/N ratios and dilution rates. To a small extent, this was due to a changing biomass composition, but much more important was the ability of uncoupling between anabolic biomass formation and catabolic energy substrate consumption. When ammonium started to limit the amount of biomass formed and hence the anabolic flow of glucose, this was totally or at least partly compensated for by an increased catabolic glucose consumption. The primary response when glucose was present in excess of the minimum requirements for biomass production was an increased rate of respiration. The calculated specific oxygen consumption rate, at D = 0.07 h-1, was more than doubled when an additional nitrogen limitation was imposed on the cells compared with that during single glucose limitation. However, the maximum respiratory capacity decreased with decreasing nitrogen concentration. The saturation level of the specific oxygen consumption rate decreased from 5.5 to 6.0 mmol/g/h under single glucose limitation to about 4.0 mmol/g/h at the lowest nitrogen concentration tested. The combined result of this was that the critical dilution rate, i.e., onset of fermentation, was as low as 0.10 h-1 during growth in a medium with a low nitrogen concentration compared with 0.20 h-1 obtained under single glucose limitation.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=204933Documentos Relacionados
- Glycolytic flux is conditionally correlated with ATP concentration in Saccharomyces cerevisiae: a chemostat study under carbon- or nitrogen-limiting conditions.
- Expression of Helicobacter pylori urease genes in Escherichia coli grown under nitrogen-limiting conditions.
- Physiological Role for the GlnK Protein of Enteric Bacteria: Relief of NifL Inhibition under Nitrogen-Limiting Conditions
- The patB gene product, required for growth of the cyanobacterium Anabaena sp. strain PCC 7120 under nitrogen-limiting conditions, contains ferredoxin and helix-turn-helix domains.
- Properties of Trichomonas vaginalis grown under chemostat controlled growth conditions.