BacterioFiles 407 - Fungus Facilitates Phototroph Feeding

Various Phomopsis fungi

Probably the last episode of the year. See you in the next!

This episode: Fungus living inside plants helps them form partnerships with nitrogen-fixing bacteria!

Download Episode (5.9 MB, 8.5 minutes)

Show notes:
Microbe of the episode: Prevotella intermedia

Takeaways
Plants are very good at acquiring carbon, but they can often use some help with other nutrients. Many form partnerships with microbes such as nitrogen-fixing bacteria or mycorrhizal fungi that can help gather nutrients from the soil better than the plants' own roots.

In this study, legume plants could form a partnership with nitrogen-fixing bacteria in its roots, but a fungus living inside the plant could enhance this partnership even more, increasing the amount of nitrogen acquired and influencing the community of microbes around the plant roots in ways favorable to all partners.

Journal Paper:
Xie X-G, Zhang F-M, Yang T, Chen Y, Li X-G, Dai C-C. 2019. Endophytic Fungus Drives Nodulation and N₂ Fixation Attributable to Specific Root Exudates. mBio 10:e00728-19, /mbio/10/4/mBio.00728-19.atom.

Other interesting stories:

• Diet could affect antibiotic impact on the gut microbiome
• Feeding gut microbes particular preferred foods can manipulate the community structure

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

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BacterioFiles 406 - Different DNA Destroys Disease Drivers

Neisseria gonorrhoeae colonies on agar
By Xishan01, CC BY-SA 3.0

This episode: DNA from related species can kill certain pathogens when they incorporate it into their genome!

Download Episode (7.9 MB, 11.5 minutes)

Show notes:
Microbe of the episode: Ungulate tetraparvovirus 3

Paper summary (paywall)

Takeaways
Neisseria gonorrhoeae, the bacteria that cause gonorrhea, have the unusual ability of taking up DNA from their surroundings at any time and making use of it in their own genome. This helps them acquire useful traits that help them survive better, such as antibiotic resistance. But it turns out that the ability is also a secret weakness!

This study showed that when N. gonorrhoeae takes up DNA from harmless, commensal species of Neisseria in the body, the DNA is similar enough to be incorporated into the genome but different enough that it kills the pathogen. This effect also occurs with a serious pathogen in the same genus, N. meningitidis.

Journal Paper:
Kim WJ, Higashi D, Goytia M, Rendón MA, Pilligua-Lucas M, Bronnimann M, McLean JA, Duncan J, Trees D, Jerse AE, So M. 2019. Commensal Neisseria Kill Neisseria gonorrhoeae through a DNA-Dependent Mechanism. Cell Host Microbe 26:228-239.e8.

Other interesting stories:

• Kombucha could be good model system for studying microbial cooperation
• Antidepressants can modify bacterial metabolism of serotonin in the gut

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.

BacterioFiles 405 - Coated Colonizers Counteract Corrosion

Coated bacteria on a coated surface
Rijavec et al. 2019, Adv Sci 1901408

This episode: Coating metal surfaces with artificial biofilms could help keep the surfaces corrosion-free even in the ocean!

Download Episode (6.3 MB, 9.1 minutes)

Show notes:
Microbe of the episode: Hymenopteran ambidensovirus 1

Takeaways
The ocean can be a harsh place for metal surfaces. Between the water, the salt, and oxygen (near the surface), corrosion is a common reality. Microbes in the ocean can contribute to this too, degrading metal structures to obtain energy for their metabolism. They colonize surfaces in biofilms that can be difficult to remove, a process called biofouling.

In this study, instead of trying to remove or prevent biofilms on surfaces, artificial biofilms were created by coating the surfaces and specially selected bacterial cells with polymers. This approach did not prevent colonization by other organisms in the sea, but preliminary results suggested that the community that did take up residence was not as corrosive as the communities found on uncoated steel.

Journal Paper:
Rijavec T, Zrimec J, Spanning R van, Lapanje A. 2019. Natural Microbial Communities Can Be Manipulated by Artificially Constructed Biofilms. Adv Sci 6:1901408.

Other interesting stories:

• Some microbe biofilms can protect outdoor metal sheets from corrosion
• How bacteria can be helpful for growing edible mushrooms (review)

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.

BacterioFiles 404 - Phages Force Food Finding

Synechococcus cyanobacteria

This episode: Another climate-related story: Cyanobacteria infected by viruses continue taking up nutrients from their environment, using it to make more viruses than would otherwise be possible!

Download Episode (6.3 MB, 9.2 minutes)

Show notes:
Microbe of the episode: Microcystis virus Ma-LMM01

News item

Takeaways
Though global warming is a global problem, accurate models for predicting where things are headed need to incorporate the activity of even the smallest organisms, if they're numerous enough. Photosynthesis and other activities of microbes in the oceans are a big sink for carbon, but cycles of other nutrients and also viruses can affect the carbon cycle.

In this study, phages infecting photosynthetic ocean bacteria were able to continue their host's uptake of nitrogen from the environment even after mostly shutting down the host's own protein production and growth. This has implications for how viruses affect carbon cycling by cyanobacteria and how quickly populations of these bacteria may grow or die off.

Journal Paper:
Waldbauer JR, Coleman ML, Rizzo AI, Campbell KL, Lotus J, Zhang L. 2019. Nitrogen sourcing during viral infection of marine cyanobacteria. Proc Natl Acad Sci 116:15590–15595.

Other interesting stories:

• Transplants of gut microbes help koalas eat wider range of food
• Skin bacteria can help attract (or repulse) mosquitoes (paper)

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.

BacterioFiles 403 - Mercury Modifies Microbe Metabolism

This episode: First episode of a climate-related arc! Considering microorganisms is important when predicting the amount of carbon coming from soil as temperature increases!

Download Episode (4.7 MB, 6.75 minutes)

Show notes:
Microbe of the episode: Streptomyces virus Zemlya

News item

Takeaways
Soil as a whole has a big influence on the climate of the planet, by enabling the communities of organisms that live in it to interact and grow, taking up gases from the atmosphere and putting others back in. Even aside from plants that grow in it, the other organisms in soil can respire and break down compounds to produce CO₂, adding to what's in the atmosphere already.

There has long been observed a relationship between ambient temperatures and this respiration in soil, such that more heat means more activity and more gases released from the soil, but today's study found that the microbial biomass in a given piece of land can have a big effect on the temperature/respiration relationship.

Journal Paper:
Čapek P, Starke R, Hofmockel KS, Bond-Lamberty B, Hess N. 2019. Apparent temperature sensitivity of soil respiration can result from temperature driven changes in microbial biomass. Soil Biol Biochem 135:286–293.

Other interesting stories:

• Phosphate-solubilizing bacteria could help replace fertilizer for plants (paper)
• Ciliate protists have bacterial microbiomes too

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.

BacterioFiles 402 - Microbe Membranes Mobilize Microglia

Microglia in rat brain tissue

This episode: Gut microbes can stimulate immune cells in mouse brains to fight off viral infections!

Download Episode (9.0 MB, 13.0 minutes)

Show notes:
Microbe of the episode: Streptoverticillium mobaraense

News item

Takeaways
The central nervous system, including the brain, is a protected area of the body. Pathogens that get in can do a lot of damage, including memory loss, paralysis, and death, so there's a strict barrier in healthy people that keeps most things out of this area: the blood-brain barrier. The immune system is also kept separate, so special cells called microglia do the patrolling and protection of the brain.

Nevertheless, microbes in the gut can influence the function of the immune system in the brain, even from a distance. In this study, mice lacking gut microbes did not have as effective an immune response to a virus infecting the brain, and it was found that molecules from bacterial outer membranes were sensed by microglia to activate their defensive response.

Journal Paper:
Brown DG, Soto R, Yandamuri S, Stone C, Dickey L, Gomes-Neto JC, Pastuzyn ED, Bell R, Petersen C, Buhrke K, Fujinami RS, O’Connell RM, Stephens WZ, Shepherd JD, Lane TE, Round JL. 2019. The microbiota protects from viral-induced neurologic damage through microglia-intrinsic TLR signaling. eLife 8:e47117.

Other interesting stories:

• Certain microbes associated with slower progression of degenerative disease in mice
• Fungus produces compound that neutralizes skunk odor

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.

BacterioFiles 401 - Phototrophs Fill Fungal Filaments

Algae inside fungal hypha

By Du et al. 2019

eLife e47815

This episode: In this partnership between fungus and algae, the algae eventually take up residence inside their partner!

Download Episode (8.4 MB, 12.1 minutes)

Show notes:
Microbe of the episode: Erwinia tracheiphila

News item/Summary article

Takeaways
Partnerships and cooperation between otherwise free-living organisms is common in the natural world. Partnering with a photosynthetic organism is a smart approach, allowing the partner to get its energy from the sun and making gathering nutrients easier for the phototroph, and possibly offering protection as well. But in most partnerships, each partner stays separated by its own cell membrane.

In this study, a fungus and an alga grow well together, exchanging carbon for nitrogen, similar to how lichens operate. But after a month or so of co-culture, the algae apparently enter the cells of the fungus somehow and live inside it, happily growing and dividing, turning the fungus green.

Journal Paper:
Du Z-Y, Zienkiewicz K, Vande Pol N, Ostrom NE, Benning C, Bonito GM. 2019. Algal-fungal symbiosis leads to photosynthetic mycelium. eLife 8:e47815.

Other interesting stories:

• Skin microbe transplants could produce healthier skin communities
• Algae took genes from bacteria to deal with harsh conditions

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.