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Novel Photobioreactor Development for Space Applications

Principal Investigators: Leslie Prufert-Bebout (ARC) and Halil Berberoglu (University of Texas at Austin).

Currently human life support in space depends on chemical and physical means re-supplied from Earth. Longer duration, remote manned space missions in the future will require regenerative, lightweight life support systems capable of recycling carbon, nitrogen, phosphorus, and trace elements independently in closed loop systems. On Earth human life depends upon a vast diversity of microbial communities perfectly adapted to fill these and many other critical roles, including the production of food, fuels and pharmaceuticals essential to human well-being.

In space, we are only beginning to explore the means to transport and optimize these inter-connected microbial support functions. Microbial systems will encounter similar challenges in space as humans (microgravity, radiation tolerance), in addition to micro-scale, low Reynolds number materials exchange phenomena; these will require systematic assessment, development, adaptation and optimization towards various applications. In order to enable a research program that addresses all of these factors, a platform that is reliable, flight ready and specifically designed for optimized microbial ecosystem growth, monitoring and regulation in space is required. Ideally, this platform should be designed with enough flexibility to serve as a standard platform for both experimental and functional application purposes.

With these goals in mind, we have developed the Surface Attached Bioreactor (SABR) platform. SABR makes use of interfacial phenomena to drive mass transport, which enables its operation independent of gravitational and inertial forces, making it a perfect match for extraterrestrial applications. Moreover, the significant reduction in water and overall system mass achieved by SABR make it ideal for space missions for which mass is a significant concern due to fuel up-launch requirements.

To date SABR has passed the following milestones:

  • Demonstrated growth of algal biomass using 25 times less water than conventional photobioreactors
  • Demonstrated CO2 scrubbing at two to four times higher rates than conventional reactors, with a factor of 3x less weight
  • Proven salt buildup mitigation capability

SABR can be used for a wide variety of single cell type or mixed culture systems. It can also be used with both photosynthetic (artificial or solar irradiance) and non-photosynthetic systems. The platform can be adjusted either to grow and harvest cells, or to maintain cells and harvest metabolic products by means of a passive collection design feature.

The SABR project is a collaboration between the NASA Ames Research Center, Systems Biology and Ecology Lab in the Exobiology Branch, and the Solar Energy and Biofuels Lab in the Mechanical Engineering Dept., at the University of Texas Austin. The project benefits in leveraging from 25 years NASA experience in the elucidation and manipulation of microbial carbon and nitrogen cycling pathways, including the current Dept. of Energy funded collaboration with colleagues at Lawrence Livermore National Labs and Stanford on biohydrogen production.

Phase 1 prototype and biological performance characteristics led to the SABR project being awarded additional funding through the OCT office to incorporate enhanced imaging and monitoring capabilities. Future platform enhancements for target applications will be constructed using specifically designed microbial communities for transcriptome array analyses in space coordinating genetic signaling to functional performance for modeling and prognostics development for reliability in long term operations.