Monday, September 20, 2021

463 - Selectively Stimulating Cell Squatters

Bacteriophages
By Jancheva and Böttcher
2021, JACS 143:8344-8351
CC BY 4.0
This episode: Bacteria produce a compound that causes a phage lurking in the genome of a competing species to wake up and start killing that competitor!

Download Episode (8.2 MB, 12.0 minutes)

Show notes:
Microbe of the episode: Zaire ebolavirus

News item

Takeaways
Some bacteriophages infect and immediately destroy their hosts in a burst of new viruses, while others can be stealthier, integrating their genome into the genome of the host and remaining there quietly even over multiple generations of the bacteria. When something stresses the host, such as DNA damage, these integrated phages (prophages) become active and start producing new viruses, killing their host like the other kind does.

In this study, one kind of bacteria release a chemical that wakes up phages in a competitor species of bacteria. This is helpful for competition, but even more interesting is that out of the six prophages in the competitor species, the chemical wakes up only one of them. Such selective phage induction could be interesting to study.

Journal Paper:
Jancheva M, Böttcher T. 2021. A Metabolite of Pseudomonas Triggers Prophage-Selective Lysogenic to Lytic Conversion in Staphylococcus aureus. J Am Chem Soc 143:8344–8351.

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Monday, September 13, 2021

462 - Super Ciliate Symbiont Set

Pseudoblepharisma tenue
By Muñoz-Gómez et al, 2021,
Sci Adv 7:eabg4102, CC BY 4.0
This episode: A eukaryote has symbionts living in it: green algae and also purple bacteria, a combo never seen before!

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Show notes:
Microbe of the episode: Staphylococcus virus phiETA

News item

Takeaways
Having bacteria as endosymbionts is fairly common in life on Earth: almost all eukaryotes have them in the form of mitochondria and sometimes chloroplasts. These former bacteria somehow got inside the ancestral eukaryote, either as parasites or as prey, and ended up as integral parts of their host's metabolic functions. Some organisms, especially insects, obtained bacterial endosymbionts more recently, that help them balance their metabolic needs when living on limited diets.

Algae have been known to be endosymbionts also, performing photosynthesis for their host. But in this study, a ciliate with both algae and purple photosynthetic bacteria as endosymbionts was discovered. Purple bacteria as symbionts is rare, and this combination has not been observed before. Interestingly, though algae produce oxygen through their photosynthesis, the ciliate prefers living in low-oxygen sediment at the bottom of a pond. The symbionts and their host seem to adjust their metabolisms as needed depending on the needs at the time; they may each perform photosynthesis, fermentation, or respiration if light, organic carbon, or oxygen are available.

Journal Paper:
Muñoz-Gómez SA, Kreutz M, Hess S. 2021. A microbial eukaryote with a unique combination of purple bacteria and green algae as endosymbionts. Sci Adv 7:eabg4102.

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Monday, September 6, 2021

461 - Ingrained Invader Inhibits Infectors

Lambda phage
By Hans-Wolfgang Ackermann
Swiss Institute of Bioinformatics
CC BY 4.0
This episode: Training a phage strain on bacteria can increase its ability to control those bacteria for much longer than an untrained phage!

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Show notes:
Microbe of the episode: Pepper yellow leaf curl Indonesia virus

News item

Takeaways
With resistance to antibiotics spreading more and more among deadly bacteria, finding alternatives to treat infections is becoming more important. One option is phage therapy, using viruses that infect bacteria to weaken or wipe out pathogens, but this can be tricky. Sometimes it takes too long to prepare an effective population of phage for treatment, and sometimes the target pathogen evolves resistance to the phage too quickly

In this study, a phage that was trained, or pre-evolved, to infect specific bacteria more effectively, was able to dominate the population consistently and prevent it from becoming fully resistant. For comparison, against an untrained strain of the same phage, the bacteria developed almost complete resistance after several days.

Journal Paper:
Borin JM, Avrani S, Barrick JE, Petrie KL, Meyer JR. 2021. Coevolutionary phage training leads to greater bacterial suppression and delays the evolution of phage resistance. Proc Natl Acad Sci 118.

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Monday, August 16, 2021

460 - Prokaryote Publicity Prevents Protist Processes

Emiliania huxleyi
By Alison R. Taylor
UNC Wilmington Microscopy
PLoS Biology, June 2011 Cover
CC BY 2.5
This episode: A bacterial communication signal makes algae stop growing, which helps them survive virus attacks!

Download Episode (5.3 MB, 7.7 minutes)

Show notes:
Microbe of the episode: Veillonella parvula

Takeaways
Many interesting interactions between microbes take place in the ocean. As single-celled organisms lacking complex sensory organs, many such interactions and communications are mediated by chemical signals. Some bacteria, for example, each produce small amounts of certain chemicals and release them into the environment. When the concentration of the chemical signal builds up to a certain point, the bacteria change their behavior to take advantage of their high numbers that must be present to produce so much of the signal. This process is called quorum sensing.

Some of these chemical signals can affect the behavior of organisms other than bacteria also. In this study, a common marine algal species was found to stop growing in response to a certain bacterial signal. This chemical inhibits an enzyme required for the algae to produce nucleotides to replicate their genomes. As a result, the algae are able to resist destruction by a virus that would otherwise decimate their populations.

Journal Paper:
Pollara SB, Becker JW, Nunn BL, Boiteau R, Repeta D, Mudge MC, Downing G, Chase D, Harvey EL, Whalen KE. 2021. Bacterial Quorum-Sensing Signal Arrests Phytoplankton Cell Division and Impacts Virus-Induced Mortality. mSphere 6:e00009-21.

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Monday, August 2, 2021

459 - Prokaryotes Provide Polyp Perserverance

Coral
By Brocken Inaglory
CC BY-SA 4.0
This episode: Transplanting microbes from some corals to others could help the corals survive high temperatures!

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Show notes:
Microbe of the episode: Streptomyces olivaceoviridis

News item

Takeaways
The ever-rising temperatures of our modern world are putting more and more stress on various ecosystems. This is true even on the ocean floor: record-high temperatures damage reefs by causing coral bleaching, in which corals lose their photosynthetic endosymbionts. If conditions do not improve, these corals eventually die.

Corals have microbial symbionts other than the phototrophs, also. We know from ourselves and from plants that microbes can have big effects on their hosts, so it seemed worth testing whether symbionts from more heat-resistant corals could transfer heat resistance to more vulnerable individuals. Recipients of this treatment did show enhanced heat resistance, but the microbial community composition did not always change after the treatment.

Journal Paper:
Doering T, Wall M, Putchim L, Rattanawongwan T, Schroeder R, Hentschel U, Roik A. 2021. Towards enhancing coral heat tolerance: a “microbiome transplantation” treatment using inoculations of homogenized coral tissues. Microbiome 9:102.

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Monday, July 19, 2021

458 - Slimy Cells Stop Sinking

Colonies of strains with
different floating strengths
By Kessler et al. 2021,
J Bacteriol 203(11):e00023-21
CC BY 4.0
This episode: Bacteria can resist the force of gravity in liquid culture by covering themselves with goopy sugar polymers like parachutes!

Download Episode (10.4 MB, 15.2 minutes)

Show notes:
Microbe of the episode: Brevicoryne brassicae virus

Takeaways
Put bacteria in a centrifuge, and most of the time you end up with a compact pellet of cells at the bottom of the tube, and mostly cell-free liquid above it. Bacteria do have ways to remain suspended in liquid, even without constant stirring or shaking of the container, but swimming, for example, consumes energy.

In this study, artificial selection allowed the discovery of bacteria that could resist centrifuging speeds up to 15000 times the force of gravity, remaining suspended in liquid instead of forming a pellet. Production of polysaccharide was important, but not sufficient; for the most resistance to sinking, bacteria had to attach the polysaccharide to their cell surface, to act as a sort of parachute.

Journal Paper:
Kessler NG, Caraballo Delgado DM, Shah NK, Dickinson JA, Moore SD. 2021. Exopolysaccharide Anchoring Creates an Extreme Resistance to Sedimentation. J Bacteriol 203(11):e00023-21.

Other interesting stories:

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Monday, June 28, 2021

457 - Small Cell Studies: Superior Scoops

Plant microbiome
By KMG Dastogeera et al.
CC BY-SA 4.0
This episode: Newspapers report on scientific studies about microbiomes a fair amount, but certain kinds of studies are more likely than others to show up in the news!

Download Episode (5.7 MB, 8.3 minutes)

Show notes:
Microbe of the episode: Cafeteriavirus-dependent mavirus

Takeaways
Research into the human microbiome has generated a lot of interest, even among non-scientists. This is especially true since the beginning of the Human Microbiome Project in 2007. But sometimes things are lost in translation from published studies into general news.

This study is a survey of microbiome studies reported in six different news sources from three different countries, either general news or business news. General news did a better job reporting on different kinds of microbiome studies proportionally, but certain kinds of studies were reported on proportionally more or less frequently than they were published.

Journal Paper:
Prados-Bo A, Casino G. 2021. Microbiome research in general and business newspapers: How many microbiome articles are published and which study designs make the news the most? PLOS ONE 16:e0249835.

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Monday, June 21, 2021

456 - Invader Induces Increased Immensity

Sulfolobus infected
with STSV1
By Xiangyux
From Wikipedia
This episode: A virus of archaea stops cells from dividing, so they just keep getting bigger and releasing more viruses!

Download Episode (6.9 MB, 10.1 minutes)

Show notes:
Microbe of the episode: Streptomyces caelestis

Takeaways
Viruses affect their hosts many different ways: instant hostile takeover of cellular machinery, lurking unseen in the genome for generations, inducing reduced cell division or excessive cell division, and more. Archaeal viruses are relatively unknown in their genetic abilities and lifestyles, but we do know that they tend not to destroy their hosts through explosive viral reproduction, and that some archaea have eukaryote-like cell cycle phases.

In this study, some viruses infecting a thermophilic archaeon interrupt its cycle in the growth phase, so hosts expand in size up to around 17 times normal, continuously releasing new viruses over time. Eventually some archaea in the population gain resistance to the viruses via their CRISPR/Cas systems, and normal-sized cells dominate the population again.

Journal Paper:
Liu J, Cvirkaite-Krupovic V, Baquero DP, Yang Y, Zhang Q, Shen Y, Krupovic M. 2021. Virus-induced cell gigantism and asymmetric cell division in archaea. Proc Natl Acad Sci 118:e2022578118.

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Monday, June 7, 2021

455 - Marine Microbes Make Megapascal Management Molecule

Myroides profundi
By Qin et al. 2021,
Sci Adv 7:eabf9941
CC BY-NC 4.0
This episode, in honor of World Ocean Day: Bacteria that may move between high and low pressure areas in the ocean use a particular molecule to protect their cells from being crushed!

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Show notes:
Microbe of the episode: Rickettsia rickettsii

News item

Takeaways
Life in the ocean can have many challenges, depending on the organism and where it lives. Microbes can be found in almost every region, from the warmest to coldest, brightest to darkest, and shallowest to deepest. Sometimes microbes are carried from shallow to deep regions, where the weight of so much water causes immense pressure, which can inhibit cellular structural integrity and function. So life in the deep sea must have ways to deal with this pressure to survive. In this study, bacteria transform a fairly common chemical into a molecule that cushions and protects their cellular structures from the effects of high pressure, allowing them to survive lower down than they would otherwise.

Journal Paper:
Qin Q-L, Wang Z-B, Su H-N, Chen X-L, Miao J, Wang X-J, Li C-Y, Zhang X-Y, Li P-Y, Wang M, Fang J, Lidbury I, Zhang W, Zhang X-H, Yang G-P, Chen Y, Zhang Y-Z. 2021. Oxidation of trimethylamine to trimethylamine N -oxide facilitates high hydrostatic pressure tolerance in a generalist bacterial lineage. Sci Adv 7:eabf9941.

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Monday, May 31, 2021

454 - Hitchhiking Horticultural Helpers

Bacteria carrying spores
By Muok et al. 2021
ISME J, CC BY 4.0
This episode: Spores of some bacteria latch onto the tails of other bacteria and ride along as they move around in the soil!

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Show notes:
Microbe of the episode: Bohle iridovirus

News item

Takeaways
The soil is a complex environment, and microbes that live in soil need complex lifestyles to thrive. There are many examples of cooperation, competition, and other adaptations to highly varied situations.

In this study, bacteria that grow like filamentous fungi don't have the mechanisms to move autonomously, but their spores can hitch rides on other kinds of bacteria that swarm through the soil using their propeller-like tails called flagella to push themselves toward the plant roots they prefer to grow near.

Journal Paper:
Muok AR, Claessen D, Briegel A. 2021. Microbial hitchhiking: how Streptomyces spores are transported by motile soil bacteria. ISME J.

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Monday, May 24, 2021

453 - Phenazine Faciliates Phosphorus Feeding

Pseudomonas aeruginosa
By Y_tambe, CC BY-SA 3.0
This episode: Some bacteria produce antibiotics that can also help them gather more nutrients!

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Show notes:
Microbe of the episode: Diadromus pulchellus toursvirus

News item 1

Takeaways
Antibiotics have saved a lot of lives since they were discovered and used to treat many previously untreatable bacterial infections. But bacteria themselves have been making antibiotics much longer than we have, to help compete in their environment. However, sometimes these compounds are not produced in large enough concentrations to act as antibiotics, killing or inhibiting rival bacteria. Why waste energy on this sublethal production? Are there other functions these molecules can perform?

In this study, bacteria produce an antibiotic called phenazine that can damage cell components by redox reactions, transferring electrons. But it can also help liberate the essential nutrient phosphorus from being bound to insoluble particles, allowing the bacteria to grow better even in the absence of competitors.

Journal Paper:
McRose DL, Newman DK. 2021. Redox-active antibiotics enhance phosphorus bioavailability. Science 371:1033–1037.
Other interesting stories:

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Monday, May 3, 2021

452 - Prokaryotic Partner Powers Protist

Anaerobic ciliate
By Graf et al. 2021
Nature, CC BY 4.0
This episode: Single-celled eukaryotes can thrive without oxygen with the help of bacterial endosymbionts that respire nitrate the way our mitochondria respire oxygen!

Thanks to Jon Graf for his contribution!

Download Episode (12.4 MB, 18.1 minutes)

Show notes:
Microbe of the episode: Brenneria salicis

News item 1 / News item 2

Takeaways
The combination of a bacterium and other microbe into the first eukaryote was a big advance in evolutionary history; it made possible the huge variety of different body shapes and sizes we see today. This is thanks to the bacterial endosymbiont, the mitochondrion, taking on specialized metabolic tasks for the cell.

We already knew about endosymbionts that help with oxygen respiration, with photosynthesis (chloroplasts), and with amino acid synthesis (certain endosymbionts in insects). But bacteria have other metabolic abilities that are very useful in certain conditions; do these bacteria ever team up with other organisms? The answer is yes! In this study, ciliates were discovered at the bottom of a lake in oxygen-free waters. These protists have an bacterial endosymbiont that helps them respire, not oxygen, but nitrate instead, generating more energy than most anaerobic ciliates.

Journal Paper:
Graf JS, Schorn S, Kitzinger K, Ahmerkamp S, Woehle C, Huettel B, Schubert CJ, Kuypers MMM, Milucka J. 2021. Anaerobic endosymbiont generates energy for ciliate host by denitrification. Nature.

Other interesting stories:

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Monday, April 19, 2021

451 - Phototrophs Fancy Floating Feasts

Prasinophyte algae
By Bock et al. 2021, ISME J
CC BY 4.0
This episode: Despite being photosynthetic, some kinds of algae engage in predatory behavior, hunting and consuming live bacteria!

Thanks to Nicholas Bock for his contribution!

Download Episode (4.9 MB, 7.1 minutes)

Show notes:
Microbe of the episode: Paramecium bursaria Chlorella virus 1

News item

Takeaways
Although most of them are microscopic, algae perform a significant portion of the photosynthesis on the planet, because there are so many of them. But even though photosynthesis seems like a reliable way of acquiring energy, there are conditions under which even algae benefit from gathering energy and nutrients from other organisms. This is called phagomixotrophy, when algae hunt and consume bacteria.

In this study, scientists developed fluorescence methods for detecting and studying this predation in a group of algal phytoplankton that's not well-studied, prasinophytes. They found that all five species they looked at engaged in bacterivory under nutrient-depleted conditions, and that they preferred live bacteria to killed ones.

Journal Paper:
Bock NA, Charvet S, Burns J, Gyaltshen Y, Rozenberg A, Duhamel S, Kim E. 2021. Experimental identification and in silico prediction of bacterivory in green algae. ISME J.

Other interesting stories:

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Monday, April 5, 2021

450 - Subterranean Spotlights Support Cyanobacteria

Carlsbad Caverns
By Eric Guinther, Marshman
CC BY-SA 3.0
This episode: Lighting in caves open to tourists supports the growth of unwanted photosynthetic bacteria!

Thanks to Zoë Havlena for her contribution!

Download Episode (6.6 MB, 9.5 minutes)

Show notes:
Microbe of the episode: Dill cryptic virus 2

Takeaways
Caves can contain amazing beauty, intricate geological formations formed by minerals, water, and time. Some, such as Carlsbad Caverns in New Mexico, have been fitted with instruments to allow tourists to pass through and see the wonders within; definitely a worthwhile experience.

Caves also have their own natural microbiota that can live within them, in the dark, somewhat cold, and nutrient-poor conditions. But with the lighting installed to allow tourism, photosynthetic microbes have been able to take hold in the communities of these show caves. These microbes can outcompete the natural microbes, and can cause discoloration and unwanted growths on cave formations. They are difficult to remove without much effort and the risk of damaging the cave formations themselves. 

This study looked at the effects of the color of lighting in the caves, as well as other factors, on the growth of these so-called "lampenflora." It supports new efforts and methods to control the issue.

Journal Paper:
Havlena Z, Kieft TL, Veni G, Horrocks RD, Jones DS. 2021. Lighting Effects on the Development and Diversity of Photosynthetic Biofilm Communities in Carlsbad Cavern, New Mexico. Appl Environ Microbiol 87.

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Monday, March 29, 2021

449 - Paralyzed Poisons Push Power

Hydrothermal vent
This episode: Deep-sea bacteria can detoxify cadmium and convert it to light-capturing particles!

Download Episode (5.8 MB, 8.4 minutes)

Show notes:
Microbe of the episode: Arthrobacter virus Sonny

Takeaways
Hydrothermal vents can have thriving communities, despite being too deep for much light to penetrate. Microbes can derive energy from chemicals coming out of the vent, and form the foundation of the food chain. But toxic heavy metals also come out of the vent, including lead, mercury, and cadmium.

The microbes in this study were found to be resistant to cadmium, which they can detoxify by combining it with the sulfur found in the amino acid cysteine. This forms cadmium-sulfur nanoparticles, which can function as light-absorbing semiconductors, allowing the bacteria to harvest light energy.

Journal Paper:
Ma N, Sha Z, Sun C. 2021. Formation of cadmium sulfide nanoparticles mediates cadmium resistance and light utilization of the deep-sea bacterium Idiomarina sp. OT37-5b. Environ Microbiol 23:934–948.

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Monday, March 22, 2021

448 - Myxomycete Makes Mycelial Memories

Slime mold on a log
By frankenstoen, CC BY 2.5
Finally found some good stories, so we're back! This episode: How slime molds encode and use memories built into their own bodies!

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Show notes:
Microbe of the episode: Aeromonas salmoncida

Takeaways
Despite being single-celled organisms, slime molds have fairly complex behavior, including a basic form of memory. They often grow as a network of tubes of cytoplasm branching out from one place to find and exploit new sources of food in their environment. When these tubes connect to new food, other less productive branches of its body shrink away.

As it turns out, this body form serves a role in memory also. This study determined that the slime mold's tubes undergo constant squeezing, which moves cell contents around and also shrinks them. When tubes are connecting to a food source though, they secrete a softening agent that allows the pressure to expand the tubes instead of shrinking them. These larger tubes consequently are capable of transporting more softening agent farther away to newer food sources, so the history of food discoveries is recorded in the slime mold's own body, which also influences its responses to new discoveries.

Journal Paper:
Kramar M, Alim K. 2021. Encoding memory in tube diameter hierarchy of living flow network. Proc Natl Acad Sci 118.
Other interesting stories:

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Monday, February 8, 2021

447 - Big Bacteria Bank Behaviors

Achromatium
By Ionescu et al. Mol Biol Evol
DOI: 10.1093/molbev/msaa273
CC BY-NC 4.0
This episode: Giant bacteria with many chromosomes in each cell carry extra genes to help them live in many different environments!

Thanks to Dr. Danny Ionescu for his contribution!

Download Episode (8.7 MB, 12.7 minutes)

Show notes:
Microbe of the episode: Propionibacterium virus SKKY

Takeaways
We think of bacteria a certain way: too small to see and having mostly just a single large chromosome with all the genes they need for their lifestyle and not much more. And most bacteria are like that. But not all! Giant bacteria exist, some of which can be so large that individual cells can be seen without a microscope.

Achromatium species are one such kind of bacteria. They form clumps of minerals that take up most of their internal volume, but their cells are big enough to see and handle. In order to supply all parts of their vast innards with proteins, they have many copies of their chromosome distributed throughout their cytoplasm.

In this study, a survey of Achromatium genomes from all different kinds of ecosystem revealed that even different species in very different environments all seem to share one set of genetic functions, but only use the ones they need for their particular lifestyle while archiving the rest.

Journal Paper:
Ionescu D, Zoccarato L, Zaduryan A, Schorn S, Bizic M, Pinnow S, Cypionka H, Grossart H-P. Heterozygous, Polyploid, Giant Bacterium, Achromatium, Possesses an Identical Functional Inventory Worldwide across Drastically Different Ecosystems. Mol Biol Evol https://doi.org/10.1093/molbev/msaa273.

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Monday, February 1, 2021

446 - Biofilm Benefits Bone Braces

Biofilm-coated implant
By Tan et al. 2020,
Sci Adv 6:eaba5723
CC BY-NC 4.0
This episode: The biofilm that probiotic bacteria can leave behind on a titanium implant seems to help it integrate better with the existing skeleton, with less inflammation and risk of infection!

Download Episode (5.5 MB, 7.9 minutes)

Show notes:
Microbe of the episode: Methylobacterium organophilum

Takeaways
Skeletal implants make it a lot easier for many people to stay mobile as they age, but the surgical procedure of implanting is risky. Its invasive nature puts stress on the immune system, which puts stress on other systems, and the spread of antibiotic resistance is increasing the risk of a hard-to-treat infection.

In this study, probiotic bacteria grow in a biofilm on titanium implants before being inactivated, leaving only the biofilm behind on the implant. This biofilm-coated implant showed improved bone integration, antimicrobial resistance that was not toxic to the body's own tissues, and reduced inflammation when implanted into rats.

Journal Paper:
Tan L, Fu J, Feng F, Liu X, Cui Z, Li B, Han Y, Zheng Y, Yeung KWK, Li Z, Zhu S, Liang Y, Feng X, Wang X, Wu S. 2020. Engineered probiotics biofilm enhances osseointegration via immunoregulation and anti-infection. Sci Adv 6:eaba5723.

Other interesting stories:

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Monday, January 25, 2021

445 - Living Lurking Landmine Locators

Bioluminescence over landmine
By Shemer et al. 2020,
Microb Biotechnol
CC BY-NC
This episode: Engineered bacteria encapsulated in little beads sense chemicals from landmines and give off light!

Download Episode (6.4 MB, 9.3 minutes)

Show notes:
Microbe of the episode: Bifidobacterium pullorum

Takeaways
Landmines are a good way to take an enemy by surprise and do some damage. They're so good that some places in the world still aren't safe to go decades after a conflict, due to intact landmines hidden in the area. In order to detect them from a distance to aid in disarming efforts, we need something very good at detecting the faint odor they give off—something like bacteria!

In this study, bacteria are engineered to detect breakdown products of TNT in landmines and produce light—bioluminescence. These bacteria are encapsulated in polymer beads and are stable for months in the freezer, and could accurately pinpoint a landmine buried in sand for a year and a half.

Journal Paper:
Shemer B, Shpigel E, Hazan C, Kabessa Y, Agranat AJ, Belkin S. Detection of buried explosives with immobilized bacterial bioreporters. Microb Biotechnol https://doi.org/10.1111/1751-7915.13683.

Other interesting stories:

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Monday, January 18, 2021

444 - Strange Sequence Stops Cell Subjugation

T4 Bacteriophage
By Victoramuse,
CC BY-SA 4.0
This episode: An interesting bacterial genetic element protects against viruses in a unique way!

Download Episode (7.1 MB, 10.3 minutes)

Show notes:
Microbe of the episode: Mongoose associated gemykibivirus 1


Takeaways
Even single-celled, microscopic organisms such as bacteria have to deal with deadly viruses infecting them. And while they don't have an immune system with antibodies and macrophages like we do, they still have defenses against infection, mostly based on sensing and destroying viral genomes. Restriction enzymes cut viral genomes at specific places, and CRISPR/Cas targets and destroys specific viral sequences. Knowing this, when microbiologists contemplate a strange genetic element of unknown function in bacteria, it's worth considering that it may be relevant to defense against phages.

The strange element in this case is retrons: a special reverse transcriptase enzyme takes a short non-coding RNA transcript and transcribes it into DNA, then links the RNA and DNA sequences together. These retrons are found in a variety of forms in a variety of microbes, and their function has been unknown up till now. In this study, one specific retron was found to defend bacteria against a number of phages. By comparing viruses, they discovered that this retron functions by sensing viruses' attempts to defeat another bacterial defense, a sort of second level of defenses. How common such a system is, what variants may exist, and how we may be able to use it for research or biotech purposes remain to be determined.

Journal Paper:
>Millman A, Bernheim A, Stokar-Avihail A, Fedorenko T, Voichek M, Leavitt A, Oppenheimer-Shaanan Y, Sorek R. 2020. Bacterial Retrons Function In Anti-Phage Defense. Cell 183:1551-1561.e12.

Other interesting stories:

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Monday, January 11, 2021

443 - Gut Group Gives Gamma Guard

Lachnospiraceae
By Public Health Image Library
Attribution
This episode: Certain gut microbes protect mice from harmful effects of high-energy radiation!

Download Episode (7.3 MB, 10.6 minutes)

Show notes:
Microbe of the episode: Solenopsis invicta virus-1


Takeaways
High-energy radiation can be very dangerous. Besides a long-term increased risk of cancer due to DNA damage, a high enough dose of radiation can cause lethal damage to multiple systems in the body, especially the gastrointestinal tract and the immune system. Finding new ways to treat or prevent damage from radiation would be very helpful for improving the safety of space travel, nuclear energy, and radiotherapy for cancer.

In this study, some mice exposed to a typically lethal dose of radiation survived without ill effects, thanks to certain microbes in their gut. Transferring these microbes to other mice helped those mice survive radiation as well, and even just the metabolites that the bacteria produced were helpful for protecting the cells in the body most affected by radiation.

Journal Paper:
Guo H, Chou W-C, Lai Y, Liang K, Tam JW, Brickey WJ, Chen L, Montgomery ND, Li X, Bohannon LM, Sung AD, Chao NJ, Peled JU, Gomes ALC, van den Brink MRM, French MJ, Macintyre AN, Sempowski GD, Tan X, Sartor RB, Lu K, Ting JPY. 2020. Multi-omics analyses of radiation survivors identify radioprotective microbes and metabolites. Science 370:eaay9097.

Other interesting stories:

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.