Cow in a Column - A Synthetic Food "Replicator"

The project tested the concept for combining waste degradation and food production in a single reactor or column, i.e., a "Cow-in-a-Column". The inputs could include space mission solid wastes, such as inedible plant biomass (largely cellulose), while the processor consisted of serial columns of immobilized microbes to first degrade the wastes and then produce high value products, such as milk fat and/or protein. The concept also could be applied to produce biofuels such as methane, biodiesel, or solvents. The project demonstrated the feasibility of the concept but requires further testing to optimize the performance. Inputs to the processor could include space mission solid wastes, such as biodegradable packaging, but focused largely on cellulose from inedible plant materials. This celluose could be the ineidible portion of biomass from plants that might be used for future life support systems (e.g., inedible leaves, stems and roots). The processor itself consisted of two reactors or compartments: The first compartment contained cellulose degrading fungi to produce simple sugars, such as glucose. The second compartment contained yeast that used the glucose to produce milk fat. The overall intent was to combine the two processes in one single reactor column, hence the name "Cow-in-a-Column". The process could also be adapted to generate high value protein, such as milk casein, or even biofuels such as methane, biodiesel, or solvents. The project involved selecting and testing various microorganisms for their ability to convert the different wastes into the target products. This also required accurate chemical assays of the end products to verify the column performance. The concepts were demonstrated by the end of the 1-year project but further testing is needed to demonstrate sustained operation and / or to expand the process to produce other products. Future testing could involve the use of genetically engineered microbes to improve the overall efficiency of converting solid wastes into edible products. More »