Mechanisms underlying the toxicity of lactone aroma compounds towards the producing yeast cells.

To study the fundamental mechanisms of toxicity of the fruity aroma compound gamma-decalactone, that lead to alterations in cell viability during its biotechnological production by yeast cells; Yarrowia lipolytica that is able to produce high amounts of this metabolite was used here as a model. Lactone concentrations above 150 mg l-1 inhibited cell growth, depolarized the living cells and increased membrane fluidity. Infrared spectroscopic measurements revealed that the introduction of the lactone into model phospholipid bilayers, decreased the phase transition temperature. Moreover, the H+-ATPase activity in membrane preparations was strongly affected by the presence of the lactone. On the other hand, only a slight decrease in the intracellular pH occurred. We propose that the toxic effects of gamma-decalactone on yeast may be initially linked to a strong interaction of the compound with cell membrane lipids and components. These findings may enable the elaboration of strategies to improve yeast cell viability during the process of lactones bioproduction.