New insights into the effect of medium-chain-length lactones on yeast membranes. Importance of the culture medium

Abstract

In hydrophobic compounds biotechnology, medium-chain-length metabolites often perturb cell activity. Their effect is usually studied in model conditions of growth in glucose media. Here, we study whether culture on lipids has an impact on the resistance of Yarrowia lipolytica to such compounds: Cells were cultured on glucose or oleate and submitted to gamma-dodecalactone. After a 60-min exposure to 3 g L(-1), about 80% of the glucose-grown cells (yeast extract peptone dextrose (YPD) cells) had lost their cultivability, 38% their membrane integrity, and 31% their reducing capacity as shown with propidium iodide and methylene blue, respectively. For oleate-grown cells, treatment at 6 g L(-1) did not alter cultivability despite some transient loss of membrane integrity from 3 g L(-1). It was shown with diphenylhexatriene and 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene that oleate-grown cells had membranes more fluid and less sensitive to the lactone-induced fluidization. Analyses revealed also higher contents of ergosterol but, for YPD- and minimum-oleate-grown cells (YNBO cells), the addition of lactone provoked a decrease in the concentration of ergosterol in a way similar to the depletion by methyl-beta-cyclodextrin and an important membrane fluidization. Ergosterol depletion or incorporation increased or decreased, respectively, cell sensitivity to lactone. This study shows that the embedment of oleate moieties into membranes as well as higher concentrations of sterol play a role in the higher resistance to lactone of oleate-grown cells (YPO cells). Similar oleate-induced increase in resistance was also observed for Rhodotorula and Candida strains able to grow on oleate as the sole carbon source whereas Saccharomyces and Sporidiobolus cells were more sensitive after induction.

Production of Dicarboxylic Acids and Flagrances by Yarrowia lipolytica

“…This effect depends on the length of the apolar part of the lactone with dodecalactone being more toxic than shorter chain-length lactones . Moreover, it was shown recently that γ-dodecalactone provoked the depletion of ergosterol in a way similar to methyl-β-cyclodextrin and that depleted cells were more sensitive to the lactone shock (Ta et al 2010). …”

“…With Y. lipolytica, it was shown that although the incorporation of oleyl moieties into the membrane made it more fluid, it also gave it a higher buffer capacity toward the incorporation of γ-dodecalactone. This was imputable to the location of the long-chain oleyl moieties into the membrane, fluidising both the polar edge and the apolar core of the membrane and modifying the polarity of the edge (Ta et al 2010). The presence of oleyl could thus reinforce the membrane against a toxic interdigitated phase transition which could be induced by the presence of short-chain compounds (Weber and De Bont 1996).…”

“…The presence of oleyl could thus reinforce the membrane against a toxic interdigitated phase transition which could be induced by the presence of short-chain compounds (Weber and De Bont 1996). Moreover, a preculture on methyl oleate induced an increase in the concentration of ergosterol and protection against the dodecalactone-induced depletion of ergosterol, suggesting a different structure of the membranes of oleate-grown cells with the possible organisation of ergosterol in microdomains protected from lactones (Ta et al 2010).…”

“…In a recent study, we have investigated the effect of an amphiphilic pre-shock (methyl oleate) on cell sensitivity to amphiphilic mediumchain-length lactones (Ta et al 2010). An increase in resistance was observed with Y. lipolytica and other lipophilic species, while other yeast species were less resistant after the pre-shock.…”

Effect of POX3 gene disruption using self-cloning CRF1 cassette in Yarrowia lipolytica on the γ-decalactone production

“…Whereas most laboratory strains were haploids strain, which could hardly be used in industrial production. Otherwise, when Yarrowia lipolytica grow on the medium that methyl ricinoleate as the only carbon source, the lactone had a marked effect on the membrane fluidity and the sterol concentration which are well known as important components in the regulation of membrane physiological properties (Ta et al 2010). The presence of increasing concentrations of copper in the growth medium may have influence on membrane integrity, accordingly affect the yields of c-decalactone.…”