Monday, June 22, 2020

425 - Paired Predators Prevent Pathogen Persistence

Haloed plaques, Bdellovibrio,
and bacteriophage
By Hobley et al. 2020,
J Bacteriol 202(6), CC BY 4.0
This episode: A bacteriophage and bacterial predator can wipe out a population of bacteria that could develop resistance to each individually!

Thanks to Laura Hobley, J. Kimberley Summers, and Jan-Ulrich Kreft for their contributions!

Also a note: I will be taking a short break from podcasts while I rebuild my collection of awesome microbiology stories to talk about.


Download Episode (6.8 MB, 9.9 minutes)

Show notes:
Microbe of the episode: Blackbird associated gemycircularvirus 1

Takeaways
Bacteriophages and bacterial predators that prey on other bacteria are both very good at killing large numbers of bacteria. But bacteria as a whole are also very good at surviving being killed in large numbers; there are almost always a few that have the right genes to overcome whatever is doing the killing. This is what makes the threat of antibiotic resistance so scary, and why phage therapy is both very promising and very limited.

In this study, however, a combination of phages and the bacterial predator Bdellovibrio bacteriovorans is able to completely eradicate a population of bacteria, or at least reduce their numbers below a detectable level. A mathematical model based on these data predicts that despite the two killers working independently, they can effectively eliminate all the individual prey organisms that would otherwise be able to resist killing by either one alone.

Journal Paper:
Hobley L, Summers JK, Till R, Milner DS, Atterbury RJ, Stroud A, Capeness MJ, Gray S, Leidenroth A, Lambert C, Connerton I, Twycross J, Baker M, Tyson J, Kreft J-U, Sockett RE. 2020. Dual Predation by Bacteriophage and Bdellovibrio bacteriovorus Can Eradicate Escherichia coli Prey in Situations where Single Predation Cannot. J Bacteriol 202.

Other interesting stories:

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

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Monday, June 15, 2020

424 - Stranger Cells Switch Stable States

Lactobacillus bacteria

Pelzer et al. 2012, PLOS One e49965

This episode: Certain bacteria can greatly affect the makeup of a microbial community, even if they quickly disappear!

Thanks to Dr. Daniel Amor for his contribution!


Download Episode (6.3 MB, 9.2 minutes)

Show notes:
Microbe of the episode: Gadgets Gully virus

News item

Takeaways
Microbial communities show more than just competition between species. Stable assemblies of many species can exist for long periods in places like the human gut, despite constant minor shifts in conditions. More major shifts, or invaders like pathogens coming in and taking over, can cause big disruptions in the community and lead to long-term gut dysbiosis, which can be, interestingly, also a stable community. 

This study shows that invaders into a community, even if they don't persist for very long, can cause a shift from one stable state to another, by favoring the dominance of a species or group that was not dominant before, for example by changing the pH of the environment. So competition is always present. This could be helpful to know for efforts to intentionally shift community structures.

Journal Paper:
Amor DR, Ratzke C, Gore J. 2020. Transient invaders can induce shifts between alternative stable states of microbial communities. Sci Adv 6:eaay8676.

Other interesting stories:

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

Subscribe: Apple Podcasts, Google Podcasts, Android, or RSS. Support the show at Patreon, or check out the show at Twitter or Facebook.

Monday, June 8, 2020

423 - Roundworm Riders Route Rootworm Resistance

Western corn rootworm adult

By Siga, CC BY-SA 4.0

This episode: Helping insect-killing bacterial symbionts of nematodes evolve resistance to chemicals that major corn pests use to defend themselves!


Download Episode (10.0 MB, 14.0 minutes)

Show notes:
Microbe of the episode: Listeria virus PSA

Takeaways
Interactions between species and even kingdoms in nature can be complex and multilayered. This means that when we want to intervene to cause a particular outcome, there may be multiple points at which we can act, but the consequences may be hard to predict.

In this study, action was taken to counteract the damage the Western corn rootworm causes to corn crops, using a tiny roundworm that attacks the insect pest with deadly bacteria. The rootworm defends itself by accumulating plant-produced toxins that inhibit the bacteria. Directed evolution was used to make the bacteria more resistant, and this led to more effective killing of the pest.

Journal Paper:
Machado RAR, Thönen L, Arce CCM, Theepan V, Prada F, Wüthrich D, Robert CAM, Vogiatzaki E, Shi Y-M, Schaeren OP, Notter M, Bruggmann R, Hapfelmeier S, Bode HB, Erb M. 2020. Engineering bacterial symbionts of nematodes improves their biocontrol potential to counter the western corn rootworm. 5. Nat Biotechnol 38:600–608.

Other interesting stories:

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

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Monday, June 1, 2020

422 - Frigid Phototrophs Fuel Fords

Algae growing in 20-liter bioreactor

Kim et. al, 2020. CC BY 4.0

This episode: Producing both biodiesel and bioethanol fuels from cold-loving Arctic algae!


Download Episode (8.7 MB, 12.6 minutes)

Show notes:
Microbe of the episode: Royal Farm virus

Takeaways
Renewable fuels such as biofuels can allow existing infrastructure and vehicles to continue to operate in a more sustainable manner, which could reduce the cost and impact of switching to new/different systems of transportation like electricity. Economically competitive methods of producing biofuels are still being explored and developed.

In this study, Arctic algae are grown in cold temperatures using only light, carbon dioxide, and a few minerals, and then broken down to produce biodiesel and bioethanol, which can be used as fuel in many different internal combustion engines. The amounts produced are comparable to other algae-based systems being researched, and use of the cold-loving organisms could reduce the cost of production in colder latitudes and seasons.

Journal Paper:
Kim EJ, Kim S, Choi H-G, Han SJ. 2020. Co-production of biodiesel and bioethanol using psychrophilic microalga Chlamydomonas sp. KNM0029C isolated from Arctic sea ice. Biotechnol Biofuel 13:20.

Other interesting stories:

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

Subscribe: Apple Podcasts, Google Podcasts, Android, or RSS. Support the show at Patreon, or check out the show at Twitter or Facebook.