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Phys.org's news article Why bacteria 'shapeshift' in space describes a recently published study Phenotypic Changes Exhibited by E. coli Cultured in Space, Zea Luis, Z. et al, 2017, Frontiers in Microbiology 8:1598, doi: 10.3389/fmicb.2017.01598.

The Phys.org article summarizes some of the results:

Because there are no gravity-driven forces in space like buoyancy and sedimentation, the only way the ISS bacteria can ingest nutrients or drugs is through natural diffusion, said Zea. The large decrease of the bacteria cell surface in space also decreases the rate of molecule-cell interaction, which may have implications for more effectively treating astronauts with bacterial infections in space.

The new study also showed the bacterial cell envelope—essentially its cell wall and outer membrane—became thicker, likely protecting the bacteria even more from the antibiotic, said Zea. The E. coli bacteria grown in space also tended to form in clumps, perhaps a defensive maneuver of sorts that may involve a shell of outer cells protecting the inner cells from antibiotics, said Zea.

In addition, some of the E. coli cells also produced outer membrane vesicles—small capsules that form outside the cell walls and act as messengers for cells to communicate with each other, Zea said. When cells with such vesicles reach a critical mass they can sync up to initiate the infection process.

"Both the increase in cell envelope thickness and in the outer membrane vesicles may be indicative of drug resistance mechanisms being activated in the spaceflight samples," said Zea. "And this experiment and others like it give us the opportunity to better understand how bacteria become resistant to antibiotics here on Earth."

I'm wondering how likely the following part of the quote from the corresponding author is to be true: "...which may have implications for more effectively treating astronauts with bacterial infections in space."

If I understand correctly, *ll of the effects related to growing in space that are described seem to be related to growing in a liquid culture medium, not inside a mammalian host. I'm not sure a bacteria which has infected an astronaut or other mammal in space will experience any difference in conditions if the host is in microgravity vs being in normal gravity. The differences seem to be specific to transport mechanisms in the culture medium, and not to any effect of weightlessness on the bacteria themselves.

Am I missing something?

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  • $\begingroup$ Be it a host or a culture medium, the micro-environment for the bacterium is the same: "because there are no gravity-driven forces in space like buoyancy and sedimentation, the only way the ISS bacteria can ingest nutrients or drugs is through natural diffusion". Have in mind that, for the bacterium, the mammalian host is indeed a liquid culture medium. $\endgroup$ – user24284 Sep 14 '17 at 11:07
  • $\begingroup$ @GerardoFurtado can you consider posting that as an answer so I can see how well others agree with it? I believe there are several transport mechanisms in living organisms that do not exist in a culture medium, from circulation of blood down to intracellular transport. A living mammal is not the same a bottle of liquid. $\endgroup$ – uhoh Sep 14 '17 at 11:14
  • $\begingroup$ Thanks, but as I told you before (your question about nitric oxide), I'm avoiding writing answers here at Bio SE for complex questions like yours. If you don't write an answer with two dozen references and four sections people downvote you. As a personal rule, now I only write answers if it takes me less than 5 minutes... oh, and species-id, I like those questions: easy to answer and nobody bothers you. Anyway, I hope someone helps you here, good luck. $\endgroup$ – user24284 Sep 14 '17 at 11:18
  • $\begingroup$ @GerardoFurtado very well then, this one is for you! Species identification; clusters of big plump red bugs in Taipei $\endgroup$ – uhoh Sep 14 '17 at 13:00

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