471 - Phage Fight Foils Fitness

Shigella phage A1-1
By Kortright et al., 2022.
AEM 2022, 88(e01514).
CC BY-4.0

This episode: A phage both kills bacterial pathogens and selects for reduced virulence!

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Show notes:
Microbe of the episode: Helminthosporium victoriae 145S virus

 

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Takeaways

Using bacteria-killing viruses to treat bacterial infections, or phage therapy, can be a good alternative to antibiotics in some situations when there are no effective antibiotics for a particular infection. But bacteria can evolve resistance to phages as well as antibiotics, often with little cost to their fitness.

In this study, a phage not only could treat an infection by attacking the bacteria, but the bacterial hosts that do evolve resistance to the phage do so by getting rid of certain structures that help them to cause more serious infection. Thus, therapy with this phage may both reduce the bacterial load and also make those remaining less virulent.

Journal Paper:
Kortright KE, Done RE, Chan BK, Souza V, Turner PE. 2022. Selection for Phage Resistance Reduces Virulence of Shigella flexneri. Appl Environ Microbiol 88:e01514-21.

Other interesting stories:

• Plastic-eating bacteria could produce biodegradable plastic
• Harmless variant of acne bacteria could help prevent more serious skin infection

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470 - Super Small Symbionts Soothe Symptoms

Tiny symbiont Saccharibacteria (yellow-green)
on host bacteria (red)
By Utter et al.,
CC BY-SA 4.0

This episode: Tiny bacteria that live on larger bacteria reduce the inflammation and gum disease the bigger microbes cause in the mouths of mice!

Download Episode (6.3 MB, 9.2 minutes)

Show notes:
Microbe of the episode: Actinomadura viridilutea

Takeaways

Even bacteria can be hosts to smaller symbionts living on them. Some kinds of these extremely tiny bacteria live in various parts of our bodies, and are sometimes associated with inflammation and the resulting disease. But being associated with something isn't necessarily the same as causing that thing.

In this study, tiny bacteria living on other bacteria in the mouths of mice were found to reduce the inflammation caused by their bacterial hosts, resulting in less gum disease and bone loss in the jaw. Even when the tiny bacteria were no longer present, their former bacterial hosts were still less disruptive to the mouse mouth.

Journal Paper:
Chipashvili O, Utter DR, Bedree JK, Ma Y, Schulte F, Mascarin G, Alayyoubi Y, Chouhan D, Hardt M, Bidlack F, Hasturk H, He X, McLean JS, Bor B. 2021. Episymbiotic Saccharibacteria suppresses gingival inflammation and bone loss in mice through host bacterial modulation. Cell Host Microbe 29:1649-1662.e7.

Other interesting stories:

• Anti-tumor bacteria: engineered E. coli colonizes tumors and attracts immune response
• Cats have skin bacteria that could inhibit drug resistant pathogens

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469 - Prophage Provides Partial Protection

Salmonella invading cells

This episode: A virus lurking in a bacterial genome protects its host population from infection with other phages, by killing off infected cells!

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Show notes:
Microbe of the episode: Olive latent ringspot virus

Takeaways

Many bacteriophages just go in and gobble up all their host's resources to make a bunch of new viruses right away. Others play a longer game, splicing into and lurking in the host's genome across multiple generations until conditions are right to multiply more rapidly. It is beneficial to these latter kind when their host is resistant to the fast-killing variety, but how can bacteria be resistant to some phages but not others?

In this study, one prophage (the phage genome integrated into the bacterial genome) carries a gene that does this in an interesting way. It prevents invading phages from replicating and kills the host cell so the infection can't spread, protecting the population (and all the other cells containing the prophage). It also contains an immunity element that allows the prophage to replicate itself without interference.

Journal Paper:
Owen SV, Wenner N, Dulberger CL, Rodwell EV, Bowers-Barnard A, Quinones-Olvera N, Rigden DJ, Rubin EJ, Garner EC, Baym M, Hinton JCD. 2021. Prophages encode phage-defense systems with cognate self-immunity. Cell Host Microbe 29:1620-1633.e8.

Other interesting stories:

• Migration affects birds' gut microbiota
• Sometimes E. coli can keep Salmonella from causing problems in the gut

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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468 - Commensal Can Kill Cholera

Vibrio cholerae

This episode: Harmless gut microbes resist cholera with good defense or better offense!

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Show notes:
Microbe of the episode: Streptomyces corchorusii

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Takeaways

The community of microbes in our guts is highly diverse, yet generally they all coexist relatively peacefully. Some pathogens can invade this community and cause massive disruptions. Cholera is a disease caused by a pathogen that injects its competing bacteria with toxins and disrupts the health of the gut, leading to very watery diarrhea that can quickly dehydrate victims.

This study found that some microbes commonly found harmlessly existing in the gut can resist destruction by the cholera pathogen. One of these resists by striking back with its own toxin injection system; the other creates a barrier of slime around itself that keeps the invader's toxins from reaching it. Such resistant gut microbes could help to reduce the threat of diseases such as cholera.

Journal Paper:
Flaugnatti N, Isaac S, Lemos Rocha LF, Stutzmann S, Rendueles O, Stoudmann C, Vesel N, Garcia-Garcera M, Buffet A, Sana TG, Rocha EPC, Blokesch M. 2021. Human commensal gut Proteobacteria withstand type VI secretion attacks through immunity protein-independent mechanisms. Nat Commun 12:5751.

Other interesting stories:

• Producing super-strong fibers with engineered microbes
• Some gut bacteria store some drugs inside their cells

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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467 - Prion Pivots Productive Pathways

Saccharomyces yeast
By Mogana Das Murtey and
Patchamuthu Ramasamy
CC BY-SA 3.0

This episode: Prions in yeast can allow better adaptation to changing conditions!

Thanks to David Garcia for his contribution!

Download Episode (9.5 MB, 13.9 minutes)

Show notes:
Microbe of the episode: Hepatovirus F

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Takeaways

Prions can be deadly. They're misshapen proteins that cause a cascade of misfolding of similar proteins if they get into the nervous system, resulting in neurodegeneration in mammals. But in other organisms, they are not always so scary; some fungi use prions to regulate their behavior in varying conditions.

In this study, a prion allows yeast to switch between a fast-growing lifestyle with shorter reproductive lifespan that can be beneficial in conditions where nutrients are often plentiful, and a slower-growing but more enduring lifestyle that helps in more scarce conditions.

Journal Paper:
Garcia DM, Campbell EA, Jakobson CM, Tsuchiya M, Shaw EA, DiNardo AL, Kaeberlein M, Jarosz DF. 2021. A prion accelerates proliferation at the expense of lifespan. eLife 10:e60917.

Other interesting stories:

• Modified yeast probiotic could tune its effects as needed by sensing bowel inflammation

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466 - Microbes Mining Mars Minerals

Basalt close up
By Helgi, CC BY-SA 4.0

This episode: Bacteria are able to extract metals from rocks for industrial use, even in microgravity!

Download Episode (6.2 MB, 9.0 minutes)

Show notes:
Microbe of the episode: Decapod ambidensovirus 1

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Takeaways

As humanity makes progress toward becoming an interplanetary species, consideration is needed on how travelers can survive and thrive in distant places. These methods may look very different from what works well on Earth, with differences in gravity, atmosphere, and access to resources. For example, mining for materials for construction may not be feasible using methods common on Earth. An alternative may be biomining, using microbes that can selectively extract and purify specific metals from minerals.

In this study, the European Space Agency tested the ability of several microbes to extract vanadium from rocks in different gravity conditions, on the International Space Station. Two out of three microbes were able to extract twice as much vanadium as was extracted in the absence of microbes, both on a planet and up in space.

Journal Paper:
Cockell CS, Santomartino R, Finster K, Waajen AC, Nicholson N, Loudon C-M, Eades LJ, Moeller R, Rettberg P, Fuchs FM, Van Houdt R, Leys N, Coninx I, Hatton J, Parmitano L, Krause J, Koehler A, Caplin N, Zuijderduijn L, Mariani A, Pellari S, Carubia F, Luciani G, Balsamo M, Zolesi V, Ochoa J, Sen P, Watt JAJ, Doswald-Winkler J, Herová M, Rattenbacher B, Wadsworth J, Everroad RC, Demets R. 2021. Microbially-Enhanced Vanadium Mining and Bioremediation Under Micro- and Mars Gravity on the International Space Station. Front Microbiol 12:663.

Other interesting stories:

• A prokaryote with internal metabolic compartments (paper)

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465 - Partners Produce Predator Prevention

Fungus cells with 
bacterial symbionts
By Büttner et al. 2021
PNAS 118:e2110669118
CC BY-NC-ND 4.0

This episode: Bacteria living inside soil fungus produce toxins that can protect their host from tiny predators!

Download Episode (7.7 MB, 11.2 minutes)

Show notes:
Microbe of the episode: Mycobacterium virus DLane

Takeaways

Soils have many different organisms cooperating and competing for resources. Some little worms called nematodes prey on fungi in the soil, while fungi may effectively defend themselves or strike back with toxins or traps that catch and kill the worms. On top of these interactions are other organisms that interact in various ways. In this study, bacteria living inside a kind of soil fungus produce toxins that defend the fungus against predatory nematodes.

Journal Paper:
Büttner H, Niehs SP, Vandelannoote K, Cseresnyés Z, Dose B, Richter I, Gerst R, Figge MT, Stinear TP, Pidot SJ, Hertweck C. 2021. Bacterial endosymbionts protect beneficial soil fungus from nematode attack. Proc Natl Acad Sci 118:e2110669118.

Other interesting stories:

• Sequencing stomach bacteria to find out how prehistoric populations migrated

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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