A Low-Cost Photobioreactor for Scalable Gas Vesicle Production

Gas vesicles (GVs) are air-filled protein nanostructures (∼85 nm diameter, ∼500 nm length) with the physical property to scatter sound. This new class of contrast agent serves as an acoustic analog to green fluorescent proteins and enables ultrasound imaging of cells that have been genetically labelled with GVs. To date, methods to produce GVs rely on expensive CO ₂ shakers, limiting accessibility and scalability. In this study, we present a cost-effective and scalable protocol to produce GVs using an adapted bubble column photobioreactor design. This production method operates at approximately 10% of the cost of the state-of-the-art, while utilizing off-the-shelf components for broader accessibility and dissemination. We characterized GVs produced with both photobioreactor and shaker-incubator production methods using hydrostatic collapse pressure measurements, hydrodynamic diameter measurements, and ultrasound imaging. Our results demonstrate that GVs produced with both methods exhibit identical physicochemical properties, ensuring intercompatibility. In summary, this new protocol to produce GVs lowers the barrier to producing GVs in research labs, thereby creating the possibility of a broader use of GVs as ultrasound contrast agents and biosensors for a wide array of biomedical applications.