The podcast for microbe lovers: reporting on exciting news about bacteria, archaea, and sometimes even eukaryotic microbes and viruses.


  • 458: Slimy Cells Stop Sinking

    19/07/2021 Duração: 15min

    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 Delg

  • 457: Small Cell Studies: Superior Scoops

    28/06/2021 Duração: 08min

    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

  • 456: Invader Induces Increased Immensity

    21/06/2021 Duração: 10min

    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 dominat

  • 455: Marine Microbes Make Megapascal Management Molecule

    07/06/2021 Duração: 09min

    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! Download Episode (6.6 MB, 9.5 minutes) 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:

  • 454: Hitchhiking Horticultural Helpers

    31/05/2021 Duração: 08min

    This episode: Spores of some bacteria latch onto the tails of other bacteria and ride along as they move around in the soil! Download Episode (5.5 MB, 8.0 minutes) 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. Other interesting stories: "How microbes in permafrost could trigger a massive carbon bomb"   Email questi

  • 453: Phenazine Faciliates Phosphorus Feeding

    24/05/2021 Duração: 07min

    This episode: Some bacteria produce antibiotics that can also help them gather more nutrients! Download Episode (5.0 MB, 7.3 minutes) 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 ab

  • 452: Prokaryotic Partner Powers Protist

    03/05/2021 Duração: 18min

    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

  • 451: Phototrophs Fancy Floating Feasts

    19/04/2021 Duração: 07min

    This episode: Despite being photosynthetic, some kinds of algae engage in predatory behavior, hunting and consuming live bacteria! 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 P

  • 450: Subterranean Spotlights Support Cyanobacteria

    05/04/2021 Duração: 09min

    This episode: Lighting in caves open to tourists supports the growth of unwanted photosynthetic bacteria! 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 t

  • 449: Paralyzed Poisons Push Power

    29/03/2021 Duração: 08min

    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–

  • 448: Myxomycete Makes Mycelial Memories

    22/03/2021 Duração: 06min

    Finally found some good stories, so we're back! This episode: How slime molds encode and use memories built into their own bodies! Download Episode (4.6 MB, 6.7 minutes) Show notes: Microbe of the episode: Aeromonas salmoncida News item   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 sof

  • 447: Big Bacteria Bank Behaviors

    08/02/2021 Duração: 12min

    This episode: Giant bacteria with many chromosomes in each cell carry extra genes to help them live in many different environments! Download Episode (8.7 MB, 12.7 minutes) Show notes: Microbe of the episode: Propionibacterium virus SKKY News item   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 differe

  • 446: Biofilm Benefits Bone Braces

    01/02/2021 Duração: 07min

    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 News item   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,

  • 445: Living Lurking Landmine Locators

    25/01/2021 Duração: 09min

    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 immobi

  • 444: Strange Sequence Stops Cell Subjugation

    18/01/2021 Duração: 10min

    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 News item 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 togeth

  • 443: Gut Group Gives Gamma Guard

    11/01/2021 Duração: 10min

    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 News item 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.   Jour

  • 442: Fossil Phototroph Phagocytosis

    28/12/2020 Duração: 10min

    This episode: Algae surviving impact that killed the dinosaurs seem to have consumed other organisms to make it through the dark times! Download Episode (7.1 MB, 10.3 minutes) Show notes: Microbe of the episode: Chaetoceros tenuissimus RNA virus 01 News item Takeaways Being able to look through time and learn about what might have happened to creatures throughout Earth's history is what makes paleontology great. Everyone knows about dinosaurs and what happened to them at the end of the Cretaceous period thanks to science. But what we can learn is not limited just to large organisms; there are ways to learn about microorganisms of the past as well, including by looking at fossils!   In this study, fossils of hard-shelled algae from around the end of the dinosaurs show that many of these microbes in the oceans went extinct at the same time due to the massive space impact. Debris blocked out sunlight for years, making it difficult for photosynthetic organisms to survive. So some of these algae appear to have

  • 441: Hyphal Hijacker Helps Harvests

    21/12/2020 Duração: 08min

    This episode: A fungus-infecting virus transforms the fungal foe into a friend of its host plant! Download Episode (6.1 MB, 8.9 minutes) Show notes: Microbe of the episode: Hepacivirus J   News item Takeaways Viruses can be useful for treating various diseases, especially bacterial infections and cancer. Their ability to target certain cell types specifically makes them great at hunting down and killing disease-causing cells without harming the body's healthy tissue. And just as bacteriophages can work to treat bacterial disease in us, fungal viruses could help to treat serious fungal infections in crop plants.   In this study, a fungus-infecting virus goes beyond treating a deadly fungal disease in rapeseed plants. Fungus infected with this virus no longer causes disease, but lives in harmony with the host plant, protects it from other fungal diseases, and even helps it to grow better.   Journal Paper: Zhang H, Xie J, Fu Y, Cheng J, Qu Z, Zhao Z, Cheng S, Chen T, Li B, Wang Q, Liu X, Tian B, Collinge DB

  • 440: Prokaryotes Pay for Passage

    14/12/2020 Duração: 11min

    This episode: Bacteria pay for the privilege of cruising around soil on fungus filaments! Download Episode (7.7 MB, 11.2 minutes) Show notes: Microbe of the episode: Clostridium acetobutylicum News item Takeaways In the complex environment of soil, many different kinds of organisms coexist. Some compete with each other, while others cooperate in fascinating interactions. One example is how bacteria can swim through a film of water surrounding the filaments of fungi, allowing them to traverse more quickly and reach new locations.   In this study, an interaction between fungus and bacterium is discovered in which the bacteria benefit from the fungus in enhanced ability to travel, and the fungus benefits by absorbing vitamins that the bacteria produce.   Journal Paper: Abeysinghe G, Kuchira M, Kudo G, Masuo S, Ninomiya A, Takahashi K, Utada AS, Hagiwara D, Nomura N, Takaya N, Obana N, Takeshita N. 2020. Fungal mycelia and bacterial thiamine establish a mutualistic growth mechanism. Life Sci Alliance 3(12):202

  • 439: Microbes Mitigate Mushroom Morbidity

    30/11/2020 Duração: 07min

    This episode: Bacteria protect farmed mushrooms from damage by other bacteria by breaking down their toxins! Download Episode (4.9 MB, 7.1 minutes) Show notes: Microbe of the episode: Tomato mosaic virus Takeaways Almost all organisms are vulnerable to pathogenic microbes that make them sick or cause damage. Most also have other microbes that help them grow better or protect them from pathogens. This includes animals, plants, and also fungi. In this study, bacterial pathogens produce a toxin that causes button mushrooms to turn brown and rot. However, other bacteria can degrade this toxin and protect the fungus, and can also degrade molecules the pathogens produce to help them swarm to new places, restricting their movement. Journal Paper: Hermenau R, Kugel S, Komor AJ, Hertweck C. 2020. Helper bacteria halt and disarm mushroom pathogens by linearizing structurally diverse cyclolipopeptides. Proc Natl Acad Sci 117:23802–23806. Email questions or comments to bacteriofiles at gmail dot com. Thanks for listenin

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