Monday, November 18, 2019

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!

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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:
ńĆapek 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.

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Monday, November 11, 2019

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!

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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.

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Monday, November 4, 2019

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.

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Monday, October 21, 2019

BacterioFiles 400 - Considering Consumables' Community Correlations

Fusobacterium
This episode: Figuring out how gut communities change with changes in diet!

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Show notes:
Microbe of the episode: Hepacivirus A

News item

Takeaways
Diet can play a big role in our health. It's not a magic pill that can cure or prevent anything, but a good diet can significantly reduce many health risks for the average person, compared with a bad diet.

Diet also has a big effect on the community of microbes in our gut, and this may play a role in the health effects we see from diet, so understanding how food and microbes interact is important. This study looked at the diet quality of participants in several food categories, and correlated this with various kinds of microbes found inside them.

Journal Paper:
Liu Y, Ajami NJ, El-Serag HB, Hair C, Graham DY, White DL, Chen L, Wang Z, Plew S, Kramer J, Cole R, Hernaez R, Hou J, Husain N, Jarbrink-Sehgal ME, Kanwal F, Ketwaroo G, Natarajan Y, Shah R, Velez M, Mallepally N, Petrosino JF, Jiao L. 2019. Dietary quality and the colonic mucosa–associated gut microbiome in humans. Am J Clin Nutr 110:701–712.

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Monday, October 14, 2019

BacterioFiles 399 - Conductor Creating Carbon Canvases

Scanning probe microscope
image of graphene
By U.S. Army Material Command
CC BY 2.0
This episode: Bacteria can aide the production of the useful material graphene, using their ability to add electrons to external surfaces!

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Show notes:
Microbe of the episode: Brevibacterium frigoritolerans

News item

Takeaways
Advanced materials often take advanced techniques to create, but they offer numerous benefits: increased strength and flexibility, smaller size, more options. One such material is graphene, which is basically a sheet of carbon atoms linked together like chainmail. It is only a single atom thick but is amazingly strong, mostly transparent, and good at conducting heat and electricity.

The trick is, it's hard to make in large quantities cheaply and easily. Sheets of carbons can be obtained from blocks of graphite, but these sheets are graphene oxide, which lack the desirable properties of graphene. Chemical methods can be used to remove the oxidation, but they are harsh and difficult. Luckily, bacteria are great at microscopic remodeling. In this study, electron-transferring bacteria are able to reduce the graphene oxide to graphene with properties almost as good as are achieved by chemical reduction.

Journal Paper:
Lehner BAE, Janssen VAEC, Spiesz EM, Benz D, Brouns SJJ, Meyer AS, van der Zant HSJ. 2019. Creation of Conductive Graphene Materials by Bacterial Reduction Using Shewanella oneidensis. ChemistryOpen 8:888–895.

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Monday, October 7, 2019

BacterioFiles 398 - Marathon Microbes Maximize Mileage

Veillonella parvula
Stand Genomic Sci 2(1): 57-65
This episode: Bacteria found in the guts of serious athletes help mice exercise longer by transforming their metabolic waste!

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Show notes:
Microbe of the episode: Aggregatibacter (Actinobacillus) actinomycetemcomitans

News item

Takeaways
Our gut microbes affect many aspects of health, and many aspects of how we live affect our microbes. One such aspect is physical exertion, which has been associated with enrichment of various microbes in the guts of athletes. This observation led to the question: are these microbes just benefiting from the high levels of exertion, or are they able to contribute also?

This study found that certain such bacteria, when given to mice, enabled the mice to run for a longer period on a treadmill. These microbes break down lactic acid, which is generated in our bodies when we push our physical limits, but the study provided evidence that the longer run times were due not to removal of this waste product, but to the propionate compound produced by its degradation.

Journal Paper:
Scheiman J, Luber JM, Chavkin TA, MacDonald T, Tung A, Pham L-D, Wibowo MC, Wurth RC, Punthambaker S, Tierney BT, Yang Z, Hattab MW, Avila-Pacheco J, Clish CB, Lessard S, Church GM, Kostic AD. 2019. Meta-omics analysis of elite athletes identifies a performance-enhancing microbe that functions via lactate metabolism. Nat Med 25:1104–1109.

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Monday, September 30, 2019

BacterioFiles 397 - Plant Promotes Pathogen-Prohibiting Partner

Bacillus subtilis
By Y tambe, CCBY-SA 3.0
This episode: Plants stimulate their root bacteria to compete better, and these bacteria help the plants resist disease!

Download Episode (7.3 MB, 10.6 minutes)

Show notes:
Microbe of the episode: Bacillus circulans

Takeaways
In some ways, plants' roots are like our gut. They both absorb nutrients, and they both have complex communities of microbes living alongside the host cells. These microbes can assist their hosts in various ways, and get fed in return.

In this study, one species of root bacterium is able to compete against others by producing an antimicrobial compound. The plant stimulates this production with chemical signals, and benefits from its symbionts' increased competitiveness because the bacterium helps the plant resist infection.

Journal Paper:
Ogran A, Yardeni EH, Keren-Paz A, Bucher T, Jain R, Gilhar O, Kolodkin-Gal I. 2019. The Plant Host Induces Antibiotic Production To Select the Most-Beneficial Colonizers. Appl Environ Microbiol 85:e00512-19.

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