LAUSR

Abstract The aim of this study was to demonstrate the potential of PEF for inducing autolysis of R. glutinis, with the purpose of designing a more efficient and ecofriendly carotenoid extraction process: an extraction from fresh biomass, using cheaper, non-toxic, environmental-friendly solvents. Propidium iodide uptake and release of intracellular components revealed the irreversible electroporation of R. glutinis by PEF. Flow cytometry measurements detected morphological changes in PEF-treated R. glutinis cells during incubation caused by the autolysis triggering effect of electroporation. After submitting the fresh biomass to a PEF treatment (15 kV/cm, 150 μs) that irreversibly electroporated more than the 90% of the cells, ethanol proved ineffective for extracting carotenoids from fresh biomass of R. glutinis. However, after incubating the PEF-treated fresh biomass for 24 h at 20 °C in a pH 7 buffer, ca. 240 μg/g d.w. of carotenoids were recovered after 1 h of extraction in ethanol. The highest amount of carotenoids extracted (375 μg/g d.w.) from the PEF-treated cells of R. glutinis was obtained after having incubated them at 25 °C for 24 h in a medium of pH 8.0. The improvement in carotenoid extraction by incubating the R. glutinis cells after PEF treatment seems to be caused by PEF-triggered autolysis, which tends to disrupt the association of carotenoids with other molecules present in the cytoplasm, and causes a degradation of the cell wall.