Biological signalling supports biotechnology – Pulsed electric fields extract a cell-death inducing factor from Chlorella vulgaris

• Published in: Bioelectrochemistry (Amsterdam, Netherlands) Netherlands), 2022-02, Vol.143, p.107991, Article 107991
• Main Authors: Krust, Damaris, Gusbeth, Christian, Müller, Alexander S.K., Scherer, Daniel, Müller, Georg, Frey, Wolfgang, Nick, Peter
• Format: Article
• Language: English
• Subjects: Algae; Alternative energy sources; Apoptosis; Aquatic microorganisms; Biological activity; Biotechnology; Biotechnology - methods; Cell death; Cell Death - drug effects; Cell Survival - drug effects; Chlorella; Chlorella vulgaris; Chlorella vulgaris - metabolism; Electric fields; Electricity; Energy; Energy efficiency; Flow cytometry; Fluorescein; Fluorescein diacetate; Lipids; Mortality; Pulsed electric field treatment; Reactive oxygen species; Reactive Oxygen Species - metabolism; Signal Transduction; Water-soluble extract
• ISSN: 1567-5394; 1878-562X; 1878-562X
• DOI: 10.1016/j.bioelechem.2021.107991

•Pulsed electric field treatment extracts cell-death inducing factor from C. vulgaris.•This putative cell-death inducing factor is heat-labile and dose-dependent.•Responsiveness to cell-death inducing factor depends on the cell cycle stage.•Proposed biochemical model: induction of programmed cell death (PCD). Compared to mechanical extraction methods, pulsed electric field (PEF) treatment provides an energy-efficient and gentle alternative. However, the biological processes involved are poorly understood. The unicellular green microalga Chlorella vulgaris was used as model organism to investigate the effect of PEF treatment on biological cells. A viability assay using fluorescein diacetate measured by flow cytometry was established. The influence of developmental stage on viability could be shown in synchronised cultures when applying PEF treatment with very low specific energies where one part of cells undergoes cell death, and the other part stays viable after treatment. Reactive oxygen species generation after similar low-energy PEF treatment could be shown, indicating that PEFs could act as abiotic stress signal. Most importantly, a cell-death inducing factor could be extracted. A water-soluble extract derived from microalgae suspensions incubated for 24 h after PEF treatment caused the recipient microalgae to die, even though the recipient cells had not been subjected to PEF treatment directly. The working model assumes that low-energy PEF treatment induces programmed cell death in C.vulgaris while specifically releasing a cell-death inducing factor. Low-energy PEF treatment with subsequent incubation period could be a novel biotechnological strategy to extract soluble proteins and lipids in cascade process.