Monday, March 11, 2024

490 - Parasitoid Pox Partners

Caterpillar with
parasitoid coccoons
By Jesse Noar
CC BY 4.0

This episode: A virus partners with a parasitoid wasp to help exploit fruit fly victims!
Download Episode (7.7 MB, 11.2 minutes)

Show notes:
Microbe of the episode: Actinomadura livida

Takeaways
Parasitoid wasps have an interesting lifestyle: they inject their eggs into the larvae of other insects, and their young hatch and grow up by consuming the host from the inside. Some of these wasps also inject a virus along with the egg, which supports the wasp offspring by suppressing the host immune system.

Most of these parasitoid helper viruses are integrated into the host wasp genome and are translated and produced as needed, but in this study, an independently replicating entomopoxvirus serves as an example of a virus-wasp mutualism. The study explores how the virus can infect the wasp prey, and how it gets passed on to wasp offspring.

Journal Paper:
Coffman KA, Hankinson QM, Burke GR. 2022. A viral mutualist employs posthatch transmission for vertical and horizontal spread among parasitoid wasps. Proc Natl Acad Sci 119:e2120048119.


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Monday, January 29, 2024

489 - Soil Smell Synthesis Significance

C. elegans nematode
By Bob Goldstein
UNC Chapel Hill
CC BY-SA 3.0
This episode: Many organisms produce the smell of earth, geosmin, and many others can sense it–but why?
Download Episode (6.0 MB, 8.7 minutes)

Show notes:
Microbe of the episode: Acidianus spindle-shaped virus 1
 
 
Takeaways
The smell of soil or earth is one of the most recognizable smells, and comes largely from a chemical called geosmin, produced by many different kinds of bacteria. Many animal species are sensitive to geosmin, some attracted by it and others repelled. But it is still not entirely understood what is the evolutionary benefit to the microbes that produce it, or the reason why different animals are sensitive to it in different ways.

In this study, different geosmin-producing bacteria were paired with tiny bacteria-eating roundworms, nematodes, to see how the chemical affected their interactions. Production of geosmin affected the worms' movement, apparently inducing them to avoid colonies of the producing microbes in some cases, though the worms still sometimes fed on the bacteria. Adding geosmin to colonies of different bacteria did not affect the worms' behavior though, so other factors seem to be involved.


Journal Paper:

Zaroubi L, Ozugergin I, Mastronardi K, Imfeld A, Law C, Gélinas Y, Piekny A, Findlay BL. 2022. The Ubiquitous Soil Terpene Geosmin Acts as a Warning Chemical. Appl Environ Microbiol 88:e00093-22.


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Monday, December 11, 2023

488 - Social Slimes Synchronize Sorties

Fonticula alba
By Toret et al. 2022
Curr Biol 32:1962
CC BY 4.0

This episode: Slime mold amoebas Fonticula alba have interesting and unique foraging and reproductive behaviors!
Download Episode (7.3 MB, 10.6 minutes)

Show notes:
Microbe of the episode: Cajanus cajan Panzee virus

 
Takeaways
How did life develop from single-celled organisms acting independently into the complex, multicellular organisms we see and are today? Although it is difficult to look back through time to study how ancient organisms may have developed along this path, it is possible to investigate modern organisms that occupy a zone in between single-celled and multicellular, to see if we can get some hints to our own development, and also learn about some interesting microbes along the way!

This study into the social amoeba, or slime mold, Fonticula alba, finds that the individual amoebal cells in a population join together into collectives and break apart into individuals at different stages of their complex life cycle, depending on the status of the bacteria around them that they forage as prey. The investigators tease out the various pathways taken by these amoebas.

Journal Paper:

Toret C, Picco A, Boiero-Sanders M, Michelot A, Kaksonen M. 2022. The cellular slime mold Fonticula alba forms a dynamic, multicellular collective while feeding on bacteria. Curr Biol 32:1961-1973.e4.


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Monday, November 20, 2023

487 - Probiotic Pulverizes Pathogen Persisters

E. coli
This episode: A probiotic strain of E. coli can target and destroy pathogens that survive a treatment of antibiotics!
Download Episode (8.2 MB, 12 minutes)

Show notes:
Microbe of the episode: Streptomyces griseoruber
 
Takeaways
Antibiotic resistance is becoming more and more of a problem as bacterial pathogens develop resistance to more and more drugs. For some people who develop an infection that is resistant to everything, it's as if they were living back in the days before antibiotics were discovered, when all they could do was pray for survival. New antibiotics are needed, but even more needed are new ways of approaching treatment of infections, using innovative approaches and combinations of therapeutics.

In this study, a probiotic strain of Escherichia coli was used to target potentially pathogenic E. coli bacteria that can survive treatment with a particularly effective type of antibiotic, fluoroquinolones. This probiotic strain, called Nissle, delivers toxins directly to the survivors, preventing resistant pathogens from proliferating.


Journal Paper:
Hare PJ, Englander HE, Mok WWK. 2022. Probiotic Escherichia coli Nissle 1917 inhibits bacterial persisters that survive fluoroquinolone treatment. J Appl Microbiol 132:4020–4032.


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Monday, October 30, 2023

486 - Biohybrid Bacteria Build Biomass

Azotobacter vinelandii
This episode: Incorporating light-absorbing molecules into bacterial membranes can allow bacteria to use solar energy to transform nitrogen gas into fertilizer!
Download Episode (6.5 MB, 9.9 minutes)

Show notes:
Microbe of the episode: Wheat dwarf virus
 
Takeaways
Turning nitrogen gas into biologically useful compounds, such as protein or ammonia for fertilizer, is an essential part of the global nitrogen cycle and therefore, for agriculture. Today much fertilizer is produced from nitrogen gas by a chemical process that requires large amounts of energy, contributing to global warming. But certain bacteria can perform the same process using special enzymes much more efficiently.

In this study, a light-absorbing molecule was inserted into the cell membrane of some of these bacteria, allowing them to use light energy directly to power the nitrogen converting enzymes. These "biohybrids" were able to produce convert significantly more nitrogen gas and produce additional bacterial biomass from it, showing promise for using such an approach for more sustainable microbial fertilizer production.

Journal Paper:
Chen Z, Quek G, Zhu J, Chan SJW, Cox‐Vázquez SJ, Lopez‐Garcia F, Bazan GC. 2023. A Broad Light‐Harvesting Conjugated Oligoelectrolyte Enables Photocatalytic Nitrogen Fixation in a Bacterial Biohybrid. Angew Chem Int Ed 62:e202307101.

Other interesting stories:
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Monday, October 16, 2023

485 - Small Cell Sculpts Sticky Snot Sphere

Mucosphere with captured prey
Larsson et al. 2022.
Nat Commun 13:1301
CC BY 4.0
This episode: A marine protist predator traps prey microbes in an attractive bubble of mucus, eats what it wants, and lets the rest sink, possibly sequestering significant amounts of carbon!
Download Episode (7.8 MB, 11.4 minutes)

Show notes:
Microbe of the episode: Bat associated cyclovirus 1

News item

Takeaways
The oceans have a lot of unique, unexplored life in them. This is true on a macro level but even more on a microscopic level, with many different kinds of microbes of various groups with fascinating life strategies. And despite being microscopic, with enough of them around, they can affect the whole planet's climate in significant ways.

In this study, one protist species gets most of its nutrients from photosynthesis, but what it can't get from the sun, it takes from prey microbes by force. To catch its prey, it creates an intricate bubble of mucus called a mucosphere, and waits for other microbes to swim into it, thinking it is food, and get stuck. Then the predator chooses the prey cell it wants and abandons the rest, letting them sink to the ocean floor and locking away the carbon they contain in the process.

Journal Paper:
Larsson ME, Bramucci AR, Collins S, Hallegraeff G, Kahlke T, Raina J-B, Seymour JR, Doblin MA. 2022. Mucospheres produced by a mixotrophic protist impact ocean carbon cycling. Nat Commun 13:1301.

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Monday, October 2, 2023

484 - Bacteriophages Boost Brains

Lysogenic phage
By Rolf Lood et al.
BMC Microbiology
2008, 8:139
CC BY 2.5
This episode: Certain phages in the gut are linked with increases in performance on some cognitive tests!
Download Episode (7.5 MB, 10.9 minutes)

Show notes:
Microbe of the episode: Streptomyces bikiniensis

News item

Takeaways
Our gut microbiota includes a large number of viruses, mostly bacteriophages. These fall into two groups, the lytic kind that infects and reproduces itself immediately in a host, and the lysogenic kind that can integrate its genome into the host bacterial genome and remain dormant for long periods.

In this study, a higher proportion of lysogenic phages was correlated with increased performance on cognitive tests in multiple species. In humans, men showed a small increase in some tests and women in others. In mice and fruit flies, transplant or ingestion of phages was linked to increased memory performance.

Journal Paper:
Mayneris-Perxachs J, Castells-Nobau A, Arnoriaga-Rodríguez M, Garre-Olmo J, Puig J, Ramos R, Martínez-Hernández F, Burokas A, Coll C, Moreno-Navarrete JM, Zapata-Tona C, Pedraza S, Pérez-Brocal V, Ramió-Torrentà L, Ricart W, Moya A, Martínez-García M, Maldonado R, Fernández-Real J-M. 2022. Caudovirales bacteriophages are associated with improved executive function and memory in flies, mice, and humans. Cell Host Microbe 30:340-356.e8.


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