At 9Honey Kitchen we are regularly fascinated by the odd and unusual things that astronauts are subjected to for dinner in space in the hopes that somehow, somehow, we can feed them food that looks ok, tastes like home and still manages to save space and pack all the nutrients they need. Here on Earth, various microbes and insects consume the waste of larger creatures for sustenance only to become food themselves, sometimes for the same type of creatures that fed them earlier.
In the NASA-funded study, in Life Sciences in Space Research, researchers put artificial solid and liquid waste through a 4ft-long cylindrical system created to break waste down using microbes and anaerobic digestion, a process similar to human digestion. The team used methane produced from the process to grow the microbe Methylococcus capsulatus, which is used in animal feed and offers a good mixture of protein and fat. Recycling food waste back into food is thus very appealing, though perhaps far from delicious.
"What was novel about our work was taking the nutrients out of that stream and intentionally putting them into a microbial reactor to grow food", The Independent reports Professor House, microbe researcher at Pennsylvania State University, as commenting.
House and his team determined that the microbes they grew for consumption contained 52 percent protein and 36 percent fat, giving future astronauts a solid source of nutrition.
The team also experimented with growing other kinds of microbes and tested the system at high heat as a way to destroy potentially unsafe pathogens.
"We used materials from the commercial aquarium industry but adapted them for methane production", says House.
Poop recycling, or "biological waste treatment" as the Penn State research team is calling it, converts human waste into a potential food source. They raised the system's pH to 11 and were surprised to find a strain of the bacteria Halomonas desiderata that could thrive. This microbe is 15 percent protein and 7 percent fats. "On the surface of the material are microbes that take solid waste from the stream and convert it to fatty acids, which are converted to methane gas by a different set of microbes on the same surface". However, House says their system of turning human waste into something edible is "faster than growing tomatoes or potatoes". About 50 percent of the solid waste sample was converted into food after 13 hours in the reactor. On the International Space Station, solid waste is stored and then carefully ejected into Earth's atmosphere, which ends up being quite a hassle.
House and colleagues also attempted to grow microbes in either a high-heat or alkaline environment. "That would be a fantastic development for deep-space travel".