A temporary immersion plant propagation bioreactor with decoupled gas and liquid flows for enhanced control of gas phase

Temporary immersion bioreactors (TIBs) are being used to propagate superior plant species on a commercial scale. We demonstrate a new TIB design, a Hydrostatic-driven TIB (Hy-TIB), where periodic raising and lowering the media reservoir maintains the advantages of temporary immersion of plant tissues without requiring large amounts of gas to move the media that is a characteristic of other TIB designs. The advantage of utilizing low volumes of gas mixtures (that are more expensive than air) is shown by a doubling of the growth rate of plant root cultures under elevated (40%) oxygen in air, and with CO₂ supplementation showing improved phototrophic and photomixotrophic growth of seedless watermelon meristem cultures. The development of this bioreactor system involved overcoming contamination issues associated with utilizing very low gas flow rates and included utilizing microchip pressure sensors to diagnose unexpected changes in internal bioreactor pressure (± 20 Pa ∼0.0002 atm) caused by flexing of non-rigid plastic bag vessels. The overall design seeks to achieve versatility, scalability and minimum cost such that bioreactor technology can play an increasing role in the critical need to improve plant productivity in the face of increasing demand for food, reduced resources, and environmental degradation.