BacterioFiles 394 - Skinny Cell Structure Supports

Bacillus subtilisBy Y tambe, CC BY-SA 3.0

This episode: Not as simple as it sounds—how rod-shaped bacteria maintain their shape!

Thanks to Dr. Ethan Garner for his contribution!

Download Episode (6.3 MB, 9.2 minutes)

Show notes:
Microbe of the episode: Erwinia virus M7

News item

Takeaways
Microbes seem like they should be a lot simpler than large multicellular organisms, but even what seems like it should be a simple system in microbes can be surprisingly complex. In this case, the system bacteria maintaining their particular cell shape.

Spherical cells have it easier: just add more cell material at every point. But for rods, they must make the cell longer without making it wider. How do they accomplish this? Two groups of proteins work together to help rod-shaped species grow, but how they work wasn't specifically known.

In this study, it was found that one group of proteins adds more cell material as it moves around the circumference, while the other adds structure to the cell that allows it to maintain shape. The more of these structural proteins present, the thinner the cell can stay.

Journal Paper:
Dion MF, Kapoor M, Sun Y, Wilson S, Ryan J, Vigouroux A, van Teeffelen S, Oldenbourg R, Garner EC. 2019. Bacillus subtilis cell diameter is determined by the opposing actions of two distinct cell wall synthetic systems. Nat Microbiol 4:1294–1305.

Other interesting stories:

• Giant viruses have genes encoding interesting chemical-metabolizing enzymes
• Tiny marine animal with two intriguing bacterial symbionts

Check out BacterioFiles featured in Top 10 Microbiology Podcasts

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

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BacterioFiles 393 - Prokaryote Partner Prevents Pathogen Potency

Acanthamoeba
By J Lorenzo-Morales et al. (2015).
Parasite 22: 10, CC BY 4.0

This episode: Bacterial symbionts of amoebas help them survive bacterial infection, and prevent pathogens from spreading to others as much!

Download Episode (7.5 MB, 8.1 minutes)

Show notes:
Microbe of the episode: Eubacterium dolichum

News item

Takeaways
Amoebas are free-living, single-celled organisms, but they have some things in common with some cells of our immune system (macrophages). For example, certain bacterial pathogens can infect both in similar ways. So it can be useful to study the interactions of amoebas and bacteria to learn about our own immune defenses.

In this study, the amoeba Acanthamoeba castellanii has another bacterial symbiont that helps it resist killing by the bacterial pathogen Legionella pneumophila. Once the amoebas recovered from the infection, they were more resistant to future challenges. Even better, the symbiont prevented the pathogen from transforming into a more spreadable form like it does when infecting amoebas alone.

Journal Paper:
König L, Wentrup C, Schulz F, Wascher F, Escola S, Swanson MS, Buchrieser C, Horn M. 2019. Symbiont-Mediated Defense against Legionella pneumophila in Amoebae. mBio 10:e00333-19.

Other interesting stories:

• RNA-cutting CRISPR/Cas system induces bacterial dormancy to prevent phage replication
• Gut bacteria degrade/modify many different kinds of drugs (paper)

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

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BacterioFiles 392 - Magnetic Microbes Maneuver Marine Manager

Calkinsia aureus
By djpmapleferryman
Uploaded by Shureg, CC BY 2.0

This episode: A marine protist can orient itself along magnetic fields thanks to bacterial symbionts on its surface that make magnetic nanoparticles!

Download Episode (7.2 MB, 7.9 minutes)

Show notes:
Microbe of the episode: Chlorocebus pygerythrus polyomavirus 3

Takeaways
Various kinds of bacteria can orient their movement along a magnetic field. These are called magnetotactic, and they use this ability to swim toward or away from the surface of their aquatic habitat, to adjust their oxygen exposure according to their preference.

No eukaryotic microbes have yet been discovered that can sense and react to magnetic fields like these prokaryotes. In this study, however, a protist was discovered that can do it via its partnership with ectosymbionts, or bacteria attached to its surface, that sense magnetism and orient their host's movement. In return, factors of the host's metabolism may feed its symbionts.

Journal Paper:
Monteil CL, Vallenet D, Menguy N, Benzerara K, Barbe V, Fouteau S, Cruaud C, Floriani M, Viollier E, Adryanczyk G, Leonhardt N, Faivre D, Pignol D, López-García P, Weld RJ, Lefevre CT. 2019. Ectosymbiotic bacteria at the origin of magnetoreception in a marine protist. Nat Microbiol 4:1088–1095.

Other interesting stories:

• Fungus infects mosquitoes and quickly kills them with engineered toxin
• Nose microbe helps mediate immune response to flu virus, in mouse study (paper)

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

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No episode this week

Sorry, no episode this week, possibly next week too, but I am working on some good ones.

BacterioFiles 391 - Slime Stores Sodium Sensibility

Physarum polycephalum on a log

By frankenstoen - flickr, CC BY 2.5

This episode: Slime molds can learn to get used to salt and hold on to that memory even after a period of dormancy!

Download Episode (8.9 MB, 9.7 minutes)

Show notes:
Microbe of the episode: Nocardia transvalensis

News item

Takeaways
Slime mold Physarum polycephalum has many surprisingly intelligent abilities, despite being only a single cell. Studying how these abilities work in the cell can teach us new ways that life can do things. The ability of interest here is habituation, or learning not to avoid a chemical that seems unpleasant to the cell but is not necessarily harmful, especially with a food reward.

The slime mold can become habituated to salt, in this case, learning to tolerate it enough to pass through a gradient of increasing concentration to get to some food as quickly as it crosses the same distance with no salt present. The scientists here learned that the cell takes up sodium into itself as it habituates, and holds onto both sodium and its memory through a period of hibernation.

Journal Paper:
Boussard A., Delescluse J., Pérez-Escudero A., Dussutour A. 2019. Memory inception and preservation in slime moulds: the quest for a common mechanism. Phil Trans R Soc B 374:20180368.

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

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BacterioFiles 390 - Friendly Phages Find Foes

E. coli bacteria

This episode: Bacteria carry deadly phages and use them against rival strains!

Download Episode (9.4 MB, 10.2 minutes)

Show notes:
Microbe of the episode: Bifidobacterium bifidum

News item

Takeaways
Bacteria such as Escherichia coli live in environments such as the gut with many other types of microbes, and often develop communities of microbes cooperating and/or competing with each other for resources. But in order to cooperate or compete, bacteria must first be able to identify and discriminate between themselves and others. Sometimes microbes do this by exchanging membrane molecules, or secreting chemical signals that only partners can detect, or transferring plasmids or producing antimicrobial compounds that kill competitors.

In the current study, scientists discovered a strain of E. coli that carries around phages that help them distinguish other strains and compete with them. When this strain encounters another, the phages it carries attack and destroy cells of the other strain, while leaving the carrier strain mostly unharmed. This strategy is not without cost, though; the viral proteins take resources to produce, and when there's no competing strains around, the virus can attack its carrier to some extent.

Journal Paper:
Song S, Guo Y, Kim J-S, Wang X, Wood TK. 2019. Phages Mediate Bacterial Self-Recognition. Cell Reports 27:737-749.e4.

Other interesting stories:

• E. coli adjusts its swimming to get around obstacles

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

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BacterioFiles 389 - Prokaryotes Pacify Protein Problem

E. coli bacteria

This episode: Engineered bacteria could help people digest an essential nutrient when they can't digest it themselves!

Download Episode (8.5 MB, 9.3 minutes)

Show notes:
Microbe of the episode: Kadipiro virus

News item (paywall)

Science-Based Medicine blog article about phenylketonuria, Synlogic, and engineering bacteria to treat this disorder, with lots of good detail

Takeaways
Treating genetic disorders can be very difficult. Sometimes they can be managed, with lifestyle, diet, or medication, but cure has almost always been out of the picture. With a disorder such as phenylketonuria (PKU), for example, in which the body is unable to fully metabolize the amino acid phenylalanine, diet and medication may work to some extent.

In an effort to provide better options for PKU, scientists at Synlogic, Inc have created a strain of Escherichia coli that produces phenylalanine-degrading enzymes in the gut. The hope is that ingesting this bacterium could allow PKU patients to be less restrictive with their diet.

Journal Paper:
Isabella VM, Ha BN, Castillo MJ, Lubkowicz DJ, Rowe SE, Millet YA, Anderson CL, Li N, Fisher AB, West KA, Reeder PJ, Momin MM, Bergeron CG, Guilmain SE, Miller PF, Kurtz CB, Falb D. 2018. Development of a synthetic live bacterial therapeutic for the human metabolic disease phenylketonuria. Nat Biotechnol 36:857–864.

Other interesting stories:

• Probiotic molecule induces protection in mice against viral brain infection
• E. coli growing with artificially synthesized genome (Extra information)

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

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