Metabolic flux response to salt induced stress in the halotolerant yeast Debaryomyces hansenii

Abstract

The toxic effect of NaCl and KCl, on growth of the marine yeast Debaryomyces hansenii on glucose or glycerol was studied. Above threshold value both salts inhibited specific growth rate, specific glucose and glycerol respiration rates and specific glucose fermentation rate, as well as biomass yields. The exponential inhibition constant, k, and minimum toxic concentration, cmin, were similar for all physiological parameters assayed. The effect of either salt in the specific activity of several glycolytic enzymes showed a similar inhibition pattern, although at much lower salt concentrations. In agreement with published results on glycerol phosphate dehydrogenase stimulation by salt, we present evidence in which a general glycolytic flux deviation could occur naturally during salt stress, due to the intrinsic sensitivity of the glycolytic enzymes responsible for the prosecution of glycolysis to intracellular ion concentrations.