Factors favouring the accumulation of arabinitol in the yeast Debaryomyces hansenii

Abstract

Culture conditions which lead to the intracellular accumulation of arabinitol were investigated in Debaryomyces hansenii. Arabinitol, detected in very low concentrations during the exponential phase of growth, accumulated during the stationary phase of growth in yeast extract – peptone – 1% (w/v) glucose medium. This polyol was retained intracellularly even after depletion of exogenous glucose, but was rapidly depleted during regrowth in fresh glucose medium. The accumulation of arabinitol was also favoured in media containing 1% (w/v) D-fructose, sucrose, L-arabinose, glycerol, and sodium acetate. High mannitol levels accumulated in stationary phase cells derived from growth in 1% (w/v) D-mannitol, and in these cultures only traces of arabinitol were detectable. Intracellular mannitol was also retained after the extracellular mannitol had been consumed, and was rapidly depleted during regrowth in glucose medium. Arabinitol did not accumulate in basal medium with no added carbon source, nor in media with nonmetabolizable carbon sources (D-arabinose or D-ribose). On the other hand, arabinitol accumulation was independent of the initial glucose concentration between 1% (w/v) and about 9% (w/v).