Harnessing Bacteria for Mars and Earth
May 30, 2013
So last fall NASA announced a synthetic biology scheme using bacteria to help form building blocks on Mars. The idea is to use Gram-positive bacteria called Sporosarcina pasteurii which hyrolyze urea (from the astronauts’ urine) to form ammonia:
The ammonia protonates to ammonium ion, which then precipitates calcium carbonate in the Martian dust to bind as cement. The method can produce “biological bricks” in various shapes, even printed out by a 3D printer.
Other great uses for microbes were reported at the recent American Society for Microbiology General Meeting in Denver. It turns out that microbes can thwart pathogens in unexpected places. For example:
- Wolbachia is an intracellular symbiont with a genome greatly diminished by evolution, shedding most of its genes as its host provides its needs. Most common in insect cells, the symbiont can protect its host from pathogens–for example, dengue virus and malaria parasites. So, researchers released large numbers of a Wolbachia-infected mosquito to spread in a dengue-infested area. Time will tell whether the Wolbachia actually protects humans from dengue.
- Bacteriophages (viruses that infect bacteria) are being used against Paenibacillus, a pathogen of honeybees. The advantage of bacteriophages is their specificity–they do not affect the bees’ digestive microbiome.
- Other bacteriophages are being tested to protect corals from coral bleaching, which is caused by bacteria that poison the coral’s partner algae. Coral bleaching is a growing problem because the bacterial infection is enhanced by global warming.
3 Comments
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Ultraphyte 
Nifty usage, but is this a good idea? One can generate ammonia from urea with basic chemistry (although I am not clear about the conversion of carbonate to cement). But the main issue is that introducing life to Mars could potentially contaminate our search for martian life. If we can show that Mars is definitely dead (including within the lithosphere), then by all means introduce new life if it makes sense for colonization.
The first question is, could Earth-adapted microbes even survive on Mars. Certainly not at the surface (irradiated near-vacuum). The microbes proposed would have to generate ammonia in the astronauts’ protected capsule; then the ammonia would be pumped outside.
What about “introduced” life? The thought has rarely stopped Earthlings before, when introducing life among different continents. Have you ever traveled between two continents? Every time you do that, you are carrying indigenous microbes to a new place where they’ve never been. Most likely pollen grains and insect eggs, too.
I think there is a rather large difference between introducing foreign organisms around Earth and potentially introducing them to Mars. We still want to determine if there is any native Mars life (whether or not it represents a true 2nd genesis) before we contaminate the planet. The biology will be hugely informative. If there is no life on/in Mars, then I have no problem with terraforming it. If there is life, we need to think first about what we intend to do, rather than just blundering in and changing the biota by accident.
I don’t think the issue of surface radiation matters. Humans will only live on Mars underground (or other shielded spaces). We may well live in lava tubes or spaces of our own creation. The microbes will happily live there and spread to similar environments.
This century is nicely shaping up to be the predicted century of biology. I look forward to it immensely. But that doesn’t mean we have to be careless.