BacterioFiles 378 - Medusa Makes Marble Microbes

Medusavirus

Yoshikawa et al. 2019 J Virol.

This episode: Newly discovered giant virus from a hot spring turns its amoeba hosts to stone!

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Show notes:
Microbe of the episode: Listeria virus P70

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Takeaways
Viruses come in endless different shapes, sizes, and genetic configurations. Even within the group called giant viruses there is a large amount of variety. Many of their genes are unknown, without homology to any other sequences we have acquired in other areas of life. There is great potential to learn interesting things from these viruses.

In this study, a new giant virus is discovered. Like many others, this infects amoebas, and causes them to transform from dynamic, shape-shifting cells into hard little cyst-like circles. This ability gave it the name Medusavirus. It's the first giant virus found in a relatively hot environment (a hot spring), and among other interesting features, it shows signs of multiple instances of gene transfer to and from its amoeba host.

Journal Paper:
Yoshikawa G, Blanc-Mathieu R, Song C, Kayama Y, Mochizuki T, Murata K, Ogata H, Takemura M. 2019. Medusavirus, a novel large DNA virus discovered from hot spring water. J Virol JVI.02130-18.

Other interesting stories:

• Bacteria on frog skin have antifungal potential
• Phages could enhance effectiveness of antibiotics against pathogen biofilms (paper)
• Cement-generating bacteria could make coal ash easier to store safely

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

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BacterioFiles 377 - Distributed Defense-Defeating Devices

This episode: Newly discovered CRISPR-inhibiting genes are found in many different bacterial groups!

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Show notes:
Microbe of the episode: Borrelia mazzottii

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Takeaways
The discovery of the microbial immune system, CRISPR-Cas, changed many things about the way we think of microbial ecology and interactions with microbe-infecting viruses. The CRISPR-Cas system can learn to detect new threats by capturing bits of their genetic sequences and using these to target the Cas proteins to chop up any such sequences that make it into the cytoplasm. This can greatly increase microbial survival in certain ecosystems in which viruses regularly kill a large percentage of the microbial population.

To overcome this defense, a virus has to adapt, either by acquiring mutations that change its sequence, thus escaping detection, or by acquiring anti-CRISPR proteins that shut down the microbial defense directly. These possibilities make the complex ecology even more interesting.

In this study, scientists develop a clever method for screening for new anti-CRISPR genes, and go searching for them in samples from various places (soil, animal guts, human gut). They find several new examples, which turn out to be found in many different kinds of species in many different environments.

Journal Paper:
Uribe RV, Helm E van der, Misiakou M-A, Lee S-W, Kol S, Sommer MOA. 2019. Discovery and Characterization of Cas9 Inhibitors Disseminated across Seven Bacterial Phyla. Cell Host & Microbe 25:233-241.e5.

Other interesting stories:

• Figuring out how phages gain new hosts (paper)
• Yeast cells modified to produce cheap medical cannabinoids
• Type of bacteria that digest parasitic roundworms from inside out

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

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BacterioFiles 376 - Pressurized Pollutant Pulls Products

Bacillus megaterium
By Osmoregulator, CCBY-SA 3.0

This episode: Supercritical carbon dioxide and bacteria that can grow in it make a great combination for biofuel production!

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Show notes:
Microbe of the episode: Flexibacter aggregans

Takeaways
Biofuels are an important part of humanity's move away from non-renewable resources. They have a higher energy density than batteries are yet able to achieve, giving them significant advantages for transportation purposes in which tapping into an electric grid isn't possible. Depending on the biofuel, they also have the advantage of existing infrastructure: we don't need to build a whole new system of charging or refueling stations, but can use the systems already in place.

However, biofuels as a collection of technologies still need some refinements. Yields for the more potentially sustainable approaches are low, and the lower the concentration of a soluble fuel, the more difficult it is to separate it from the non-fuel components of a fermentation. Microbial products also face the risk of contamination of a fermentation by unwanted organisms that use up the substrate without producing desirable products.

In this study, supercritical carbon dioxide is considered as a fix for both of these problems. The gas is pressurized to a point at which it is indistinguishable from liquid. A strain of Bacillus megaterium is specially selected as capable of growing and fermenting in this environment, while contaminants are inhibited. The solvent potential of supercritical carbon dioxide also serves as a way to extract the biofuel product—in this case, isobutanol—from the aqueous part of the culture medium. While it needs some development, this approach yields promising results.

Journal Paper:
Boock JT, Freedman AJE, Tompsett GA, Muse SK, Allen AJ, Jackson LA, Castro-Dominguez B, Timko MT, Prather KLJ, Thompson JR. 2019. Engineered microbial biofuel production and recovery under supercritical carbon dioxide. Nat Commun 10:587.

Other interesting stories:

• Yeast adopted useful iron-capturing bacterial protein

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

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BacterioFiles 375 - Prepared Pathogen Preserves Perception

This episode: A cancer-killing virus could help increase success of treatment of a form of eye cancer in children!

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Show notes:
Microbe of the episode: Acanthamoeba polyphaga mimivirus

News item

Takeaways
Cancer obviously is a serious concern, and can be tricky to treat because there are endless varieties in all different places in the body, each of which can have its own expected progression, aggressiveness, and methods of treatment to take into account.

Even more serious is when the cancer is in very young children, as is often the case with a cancer of the eye called retinoblastoma. There are about 8000 cases of this disease per year, and when treatment is unsuccessful, it can lead to the loss of one or both eyes.

In this study, investigators looked into using a cancer-targeting, oncolytic virus to complement the normal treatment of chemotherapy. The virus for the most part remained localized to the eye where it should be, and targeted the cancer instead of healthy cells, and so seems promising. In the small trial with two patients included in this study, the virus didn't cause a complete recovery, but showed some modest promising results.

Journal Paper:
Pascual-Pasto G, Bazan-Peregrino M, Olaciregui NG, Restrepo-Perdomo CA, Mato-Berciano A, Ottaviani D, Weber K, Correa G, Paco S, Vila-Ubach M, Cuadrado-Vilanova M, Castillo-Ecija H, Botteri G, Garcia-Gerique L, Moreno-Gilabert H, Gimenez-Alejandre M, Alonso-Lopez P, Farrera-Sal M, Torres-Manjon S, Ramos-Lozano D, Moreno R, Aerts I, Doz F, Cassoux N, Chapeaublanc E, Torrebadell M, Roldan M, König A, Suñol M, Claverol J, Lavarino C, De TC, Fu L, Radvanyi F, Munier FL, Catalá-Mora J, Mora J, Alemany R, Cascalló M, Chantada GL, Carcaboso AM. 2019. Therapeutic targeting of the RB1 pathway in retinoblastoma with the oncolytic adenovirus VCN-01. Sci Transl Med 11:eaat9321.

Other interesting stories:

• Exploring how microbes can influence the flavor of coffee

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

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BacterioFiles 374 - Microbes Muzzle Malicious Metal

Elemental arsenic
By Tomihahndorf
CC BY-SA 3.0

This episode: Mouse gut microbes, from mice or from human donors, can protect mice against arsenic toxicity!

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Show notes:
Microbe of the episode: Streptomyces griseus

News item

Takeaways
Our gut microbes benefit us in many ways, including nutritionally—by producing vitamins and helping to digest food—and by helping us in defense against pathogens and other immunological threats.

Many things we do can affect our gut microbes too, positively or negatively. What we eat, toxins we encounter, and other aspects of lifestyle can damage our microbial communities.

In this study, we see that the reverse could be true, that gut microbes, and specifically one called Faecalibacterium prausnitzii, can protect their host against toxins such as arsenic.

Journal Paper:
Coryell M, McAlpine M, Pinkham NV, McDermott TR, Walk ST. 2018. The gut microbiome is required for full protection against acute arsenic toxicity in mouse models. Nat Commun 9:5424.

Other interesting stories:

• Using bacteria to remediate rust on iron (paper)
• New large viruses discovered infecting bacteria in human gut
• Cool podcast about gardening that often mentions microbes

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

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BacterioFiles 373 - Plant Pilots Prevent Parching

Emmer wheat

This episode: Beneficial fungi found inside wild grain plants help wheat plants grow better with less water!

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Show notes:
Microbe of the episode: Beijerinckia indica

Takeaways
As we have microbial communities in our guts, on our skin, and in various other places in and on our bodies, plants also have beneficial microbial symbionts around their roots, on their leaf surfaces, and even inside their tissues. These microbes can be bacteria, fungi, or other, and can help plants gather nutrients, resist diseases or pests, and other things.

In this study, some fungi living in grain plants—called endophytes, or "inside plants"—can help wheat tolerate drought and grow better with less water. Studying this system could lead to breakthroughs in wheat farming, all thanks to microbes.

Journal Paper:
Llorens E, Sharon O, Camañes G, García‐Agustín P, Sharon A. Endophytes from wild cereals protect wheat plants from drought by alteration of physiological responses of the plants to water stress. Environ Microbiol.

Other interesting stories:

• Searching bacterial metabolites for new insect repellants
• Antibiotic disruption of gut microbes can also mess with skeletal health
• Fibers derived from wood could encourage healthy gut microbes (paper)

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

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BacterioFiles 372 - Roundworm Riders Repel Raiders

Nematode
By Bob Goldstein, UNC Chapel Hill
CC BY-SA 3.0

This episode: Bacteria that help nematodes prey on insects also help keep fungi from stealing their kills!

Download Episode (7.4 MB, 8.1 minutes)

Show notes:
Microbe of the episode: Artogeia rapae granulovirus

Takeaways
Soil is an incredibly complex ecosystem, with many different interactions constantly happening between plants, insects, bacteria, fungi, and other organisms, not to mention a large variety of shifting environmental conditions. All of these are competing with some and cooperating with others to try to survive and thrive the best they can.

One interesting interaction takes place between small roundworms in the soil, called nematodes, and bacteria they carry around that cause disease in insects. These nematodes prey on insects by injecting the bacteria into them, which kill and start digesting the insects. The nematodes then feed on the insects and the bacteria until the resources have been exhausted, and then move on to the next insect, taking some bacteria with them again.

In this study, the scientists wondered how these partners deal with competitors in the soil that might want to take advantage of their resources. They discover that the bacteria produce compounds that can repel and inhibit fungi that might otherwise steal their kills.

Journal Paper:
Shan S, Wang W, Song C, Wang M, Sun B, Li Y, Fu Y, Gu X, Ruan W, Rasmann S. The symbiotic bacteria Alcaligenes faecalis of the entomopathogenic nematodes Oscheius spp. exhibit potential biocontrol of plant- and entomopathogenic fungi. Microb Biotechnol.

Other interesting stories:

• Mice given gut microbes from healthy human babies don't get milk allergies
• New fungal species living in glaciers are losing their homes as glaciers disappear
• Toxins from cyanobacterial blooms can product tiny animals from pathogens

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

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