Toxic and useful: harnessing yeast killer toxins for product recovery

BACKGROUND: Saccharomyces cerevisiae is widely used in biotechnology to produce proteins and other biomolecules. Recovery of intracellular products, however, remains a key bottleneck for industrial applications. The robust cell wall demands energy-intensive chemical or mechanical disruption that can damage sensitive targets and result in limited product recovery. RESULTS: In this study, we investigated yeast killer toxins as a genetically encoded tool to enhance membrane permeability and facilitate intracellular product recovery. Five killer toxins with distinct modes of action were expressed intracellularly and their effects on cell survival, membrane permeability, susceptibility to lysis and enhancement of intracellular product recovery were examined. In combination with common mechanical disruption methods, toxin expression enhanced total intracellular protein recovery up to 6-fold relative to the control strain without a killer toxin expressed. CONCLUSION: These results establish killer toxin expression as a tuneable strategy for enhanced product recovery from yeast, that complements and augment conventional bioprocessing techniques.