491 - Less Liquid Lands Losing Lichens

Lichens on rock By Jesse Noar CC BY 4.0

This episode: Trends of declining lichen populations and biocrust cover overall match trends of increasing temperatures in Colorado dryland!
Download Episode (6.4 MB, 9.3 minutes)

Show notes:

Microbe of the episode: Cherry chlorotic rusty spot associated partitivirus

Takeaways:

Global climate change is affecting almost every natural system on the planet, in predictable and also sometimes unexpected, complex ways. Microbes perform key roles in many different ecosystems, providing and recycling important nutrients and even macroscopic structure. One example of this is biocrusts in dryland environments, such as areas in the western US with low annual rainfall. Microbes other organisms form a stable surface binding soil and sand particles together, helping to retain moisture and prevent erosion and transformation of land into desert.

In this study of a Colorado park over more than 20 years, important species of symbiotic fungi and photosynthetic microbes in the form of lichens have declined significantly. The land is mostly untroubled by grazing or human activity, but changes in climate and moisture and the presence of invasive plants could affect lichens. However, the temperature increase over the decades showed the best correlation with the lichen decline. The loss of these species could lead to nutrient shortages in the long term for these communities.

Journal Paper:

Finger-Higgens R, Duniway MC, Fick S, Geiger EL, Hoover DL, Pfennigwerth AA, Van Scoyoc MW, Belnap J. 2022. Decline in biological soil crust N-fixing lichens linked to increasing summertime temperatures. Proc Natl Acad Sci USA 119:e2120975119.

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

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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.

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.

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

 

News item

 

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.

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.