Fertilizer made from cyanobacteria enables plant cultivation on Mars
Researchers have produced a fertilizer from simulated Martian resources and successfully grown duckweed using it
A research team from the Center for Applied Space Technology and Microgravity (ZARM), the Department of Environmental Process Engineering (UVT) at the University of Bremen and the German Aerospace Center (DLR) has made significant progress toward a self-sufficient Mars mission: a fertilizer, which can be produced solely with Martian resources, has been successfully used to grow edible biomass.
The fertilizer is based on cyanobacteria, also known as blue-green algae. They have several properties that make them particularly suitable for the use on the Red Planet: They can use carbon dioxide from the Martian atmosphere, produce oxygen, and extract important nutrients directly from the Martian dust.
The cyanobacteria were cultivated with simulated Martian resources, including an artificially produced regolith that mimics Martian dust. The cyanobacteria are then converted into a nutrient-rich fermentation product. This is done by microbes in an anaerobic fermentation process – without any oxygen and using only materials that are potentially available on site.
In the recently published study in the Chemical engineering journal, the researchers investigated how to optimize the fermentation process. Heating the biomass before processing led to faster decomposition, while an operating temperature of 35 degrees Celsius proved ideal for the fermentation process. Moreover, the ratio between the amount of biomass used and the ammonium yield was determined. This is important as it informs how much cyanobacterial biomass to add to get the right concentration of ammonium in the fertilizer. A Mars dust simulant (MGS-1) was used as the main source of mineral nutrients, showing that the fermentation can be done using local resources.
The resulting fertilizer was used to grow duckweed (Lemna sp.), a fast-growing, protein-rich aquatic plant that has been consumed as food in Southeast Asia for centuries. Particularly noteworthy: From just one gram of dry cyanobacteria, 27 grams of fresh, edible plant mass was obtained.
Prospects for future Mars missions
“You can imagine a vegetable garden on Mars that is run entirely from local resources – without bringing soil, fertilizer, or water” explains Tiago Ramalho from the University of Bremen. “This self-sufficiency is important to make future Martian settlements as sustainable as possible!”
Lemna spp. has great potential beyond space missions: it grows quickly, is nutrient-rich, easy to cultivate, and completely edible. It is already approved as food in the EU and is considered a contender for a sustainable superfood of the future – on Earth as well as in space.
In addition to food production, the system offers another advantage: the process produces methane, which can be used as an energy source.
"This work shows how plants could be grown from natural resources on Mars, using microbes as an intermediate. It can also be a foundation for sustainable food production there" says Prof. Cyprien Verseux, head of the Laboratory of Applied Space Microbiology at ZARM.
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