Bioconversion of ricinoleic acid to (R)-γ-decalactone R )-γ-decalactone by Clavispora lusitaniae YJ26 cells in an ionic liquid-containing biphasic fermentation system

Microbial production of chiral gamma-decalactone has received considerable attention due to its high market value. However, the inhibition of substrates and products on microorganisms has significantly limited the production of chiral gamma-decalactone. In this study, a green biphasic fermentation system containing 1-butyl-3-methylimidazolium tetrafluoroborate ([C4MIM]PF6) was developed to increase the synthesis of (R)-gamma-decalactone from ricinoleic acid catalyzed by Clavispora lusitaniae YJ26. Under optimal conditions, the titer of gamma-decalactone obtained using the biphasic system reached 2.04 g/L, which is 2.4 times that of the traditional aqueous fermentation system, and showed high enantioselectivity (e.e.> 99.0%). Fluorescence microscopy and flow cytometry results demonstrated that the addition of [C4MIM]PF6 significantly alleviated the damage of substrate and product to cell membrane and improved cell viability, thus increasing the titer of gamma-decalactone. Furthermore, comparative transcriptomic analysis results suggested that the improved mechanism may be attributed to the up-regulation of genes associated with cell membrane component synthesis or cell tolerance enhancement. Overall, the experimental results provide valuable insights into the efficient microbial production of chiral decalactone in an ionic liquids-containing biphasic fermentation system.