Monday, March 18, 2019

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!

Download Episode (6.7 MB, 7.3 minutes)

Show notes:
Microbe of the episode: Listeria virus P70

News item

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.

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Monday, March 11, 2019

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

News item

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.

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Monday, March 4, 2019

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!

Download Episode (9.4 MB, 10.2 minutes)

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.

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Monday, February 25, 2019

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!

Download Episode (8.0 MB, 8.7 minutes)

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.

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Monday, February 18, 2019

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!

Download Episode (6.3 MB, 6.9 minutes)

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.

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Monday, February 11, 2019

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!

Download Episode (7.1 MB, 7.75 minutes)

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.

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Monday, February 4, 2019

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.

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Monday, January 28, 2019

BacterioFiles 371 - Cell Stalker Senses Signals

Vibrio cholerae
This episode: Phages eavesdrop on bacterial communications to attack at the perfect moment!

Thanks to Justin Silpe and Dr. Bonnie Bassler for their contributions!

Download Episode (11.1 MB, 12.2 minutes)

Show notes:
Microbe of the episode: Artichoke Aegean ringspot virus

News item

Takeaways
Even organisms as small as bacteria can, and often do, communicate with each other through a process called quorum sensing, in which each cell releases a small amount of a certain chemical into their surroundings. When the population is large enough that the concentration of this chemical builds up to a certain level, the cells in the population change their behavior. The specifics of this change depend on the species and the situation.

But since this chemical signal is released into the environment, anything around that can sense it can listen in on the communications of a bacterial population. In this study, Justin Silpe and Dr. Bonnie Bassler find a type of virus that uses such a chemical communication as a signal to come out of stasis and hijack a whole population of bacteria at once!

Journal Paper:
Silpe JE, Bassler BL. 2019. A Host-Produced Quorum-Sensing Autoinducer Controls a Phage Lysis-Lysogeny Decision. Cell 176:268-280.E13.

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Monday, January 21, 2019

BacterioFiles 370 - Magnets Make Messenger More Moveable

Baculoviruses in occlusion body
This episode: Enhancing a virus with magnetic nanoparticles and CRISPR-Cas gene editing abilities makes it a good vector for genetic therapies!

Download Episode (11.2 MB, 12.25 minutes)

Show notes:
Microbe of the episode: Staphylococcus virus S253

News item

Takeaways
Gene delivery, getting genetic content for gene therapy to the correct tissues in an organism, has long been a very tricky problem. And genetic modification, making specific changes at a specific place in a genome, is also difficult.

Viruses can help with both delivery and modification, but they're often not specific and targeted enough to be effective, or even safe. Off-target effects could be harmful or even deadly, potentially resulting in cancer.

In this study, a virus is modified with nanotechnology in the form of tiny magnets to allow humans to target it to specific tissues, and given the ability to modify specific genes using the bacterial CRISPR-Cas system. These modifications potentially make this gene delivery system much more safe and effective.

Journal Paper:
Zhu H, Zhang L, Tong S, Lee CM, Deshmukh H, Bao G. 2018. Spatial control of in vivo CRISPR–Cas9 genome editing via nanomagnets. Nat Biomed Eng.

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Monday, January 14, 2019

BacterioFiles 369 - Powering Purple Prokaryote Protonation

This episode: Purple phototrophic bacteria could use certain kinds of wastewater, along with electric current, to produce valuable products like hydrogen without much waste!

Thanks to Dr. Ioanna Vasiliadou for her contribution!

Download Episode (12.7 MB, 13.9 minutes)

Show notes:
Microbe of the episode: Streptomyces tendae

News item

Takeaways
Purple phototrophic bacteria can take light energy and use it to help power their metabolism. They're not dependent on it like plants, but can use light or other energy sources for their versatile metabolism.

This versatility makes them very interesting candidates for industrial biotechnology applications. These bacteria can take in various combinations of nutrients and produce a number of different valuable products, including protein-rich feed, bioplastics, and biofuels such as hydrogen gas.

Today's study shows they can also take up electrons directly to help make their biofuel production process even more environmentally sustainable.

Journal Paper:
Vasiliadou IA, Berná A, Manchon C, Melero JA, Martinez F, Esteve-Nuñez A, Puyol D. 2018. Biological and Bioelectrochemical Systems for Hydrogen Production and Carbon Fixation Using Purple Phototrophic Bacteria. Front Energy Res 6:107.

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Monday, January 7, 2019

BacterioFiles 368 - Prokaryotes Promote Passing Parent Peculiarities

Drosophila fruit fly
By André Karwath, CC BY-SA 2.5
This episode: Fruit fly gut microbes can mediate non-genetic traits passed from parents to offspring!

Thanks to Dr. Per Stenberg for his contribution!

Download Episode (10.0 MB, 10.9 minutes)

Show notes:
Microbe of the episode: Bifidobacterium breve

News item

Takeaways
Heritability of traits is essential for evolution; if an ability can't be passed on from generation to generation, then natural selection can't act on it on a population-wide level.

An organism's genome is the source of most heritable traits, as DNA gets passed on to offspring, but a number of other ways of passing on traits have been discovered, in the field of epigenetics.

In this study, the gut microbes from fruit flies raised in one temperature could affect the gene expression of their offspring raised in a different temperature, compared to flies that had been kept at the latter temperature over both generations. While the effects on fly fitness or behavior are not yet known, these results suggest that gut microbes, transmitted from parents to offspring, could be another mechanism of heritability.

Journal Paper:
Zare A, Johansson A-M, Karlsson E, Delhomme N, Stenberg P. 2018. The gut microbiome participates in transgenerational inheritance of low-temperature responses in Drosophila melanogaster. FEBS Lett 592:4078–4086.

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