Bacteriofiles

This episode: A phage both kills bacterial pathogens and selects for reduced virulence! Download Episode (6.3 MB, 9.9 minutes) Show notes: Microbe of the episode: Helminthosporium victoriae 145S virus   News item   Takeaways Using bacteria-killing viruses to treat bacterial infections, or phage therapy, can be a good alternative to antibiotics in some situations when there are no effective antibiotics for a particular infection. But bacteria can evolve resistance to phages as well as antibiotics, often with little cost to their fitness. In this study, a phage not only could treat an infection by attacking the bacteria, but the bacterial hosts that do evolve resistance to the phage do so by getting rid of certain structures that help them to cause more serious infection. Thus, therapy with this phage may both reduce the bacterial load and also make those remaining less virulent.   Journal Paper: Kortright KE, Done RE, Chan BK, Souza V, Turner PE. 2022. Selection for Phage Resistance Reduces Virulence of Sh

This episode: Tiny bacteria that live on larger bacteria reduce the inflammation and gum disease the bigger microbes cause in the mouths of mice! Download Episode (6.3 MB, 9.2 minutes) Show notes: Microbe of the episode: Actinomadura viridilutea   Takeaways Even bacteria can be hosts to smaller symbionts living on them. Some kinds of these extremely tiny bacteria live in various parts of our bodies, and are sometimes associated with inflammation and the resulting disease. But being associated with something isn't necessarily the same as causing that thing. In this study, tiny bacteria living on other bacteria in the mouths of mice were found to reduce the inflammation caused by their bacterial hosts, resulting in less gum disease and bone loss in the jaw. Even when the tiny bacteria were no longer present, their former bacterial hosts were still less disruptive to the mouse mouth.   Journal Paper: Chipashvili O, Utter DR, Bedree JK, Ma Y, Schulte F, Mascarin G, Alayyoubi Y, Chouhan D, Hardt M, Bidlack F,

This episode: A virus lurking in a bacterial genome protects its host population from infection with other phages, by killing off infected cells! Download Episode (7.6 MB, 11.0 minutes) Show notes: Microbe of the episode: Olive latent ringspot virus   Takeaways Many bacteriophages just go in and gobble up all their host's resources to make a bunch of new viruses right away. Others play a longer game, splicing into and lurking in the host's genome across multiple generations until conditions are right to multiply more rapidly. It is beneficial to these latter kind when their host is resistant to the fast-killing variety, but how can bacteria be resistant to some phages but not others?   In this study, one prophage (the phage genome integrated into the bacterial genome) carries a gene that does this in an interesting way. It prevents invading phages from replicating and kills the host cell so the infection can't spread, protecting the population (and all the other cells containing the prophage). It also con

This episode: Harmless gut microbes resist cholera with good defense or better offense! Download Episode (5.8 MB, 8.4 minutes) Show notes: Microbe of the episode: Streptomyces corchorusii   News item   Takeaways The community of microbes in our guts is highly diverse, yet generally they all coexist relatively peacefully. Some pathogens can invade this community and cause massive disruptions. Cholera is a disease caused by a pathogen that injects its competing bacteria with toxins and disrupts the health of the gut, leading to very watery diarrhea that can quickly dehydrate victims.   This study found that some microbes commonly found harmlessly existing in the gut can resist destruction by the cholera pathogen. One of these resists by striking back with its own toxin injection system; the other creates a barrier of slime around itself that keeps the invader's toxins from reaching it. Such resistant gut microbes could help to reduce the threat of diseases such as cholera.   Journal Paper: Flaugnatti N, Is

This episode: Prions in yeast can allow better adaptation to changing conditions! Download Episode (9.5 MB, 13.9 minutes) Show notes: Microbe of the episode: Hepatovirus F   News item   Takeaways Prions can be deadly. They're misshapen proteins that cause a cascade of misfolding of similar proteins if they get into the nervous system, resulting in neurodegeneration in mammals. But in other organisms, they are not always so scary; some fungi use prions to regulate their behavior in varying conditions.   In this study, a prion allows yeast to switch between a fast-growing lifestyle with shorter reproductive lifespan that can be beneficial in conditions where nutrients are often plentiful, and a slower-growing but more enduring lifestyle that helps in more scarce conditions.   Journal Paper: Garcia DM, Campbell EA, Jakobson CM, Tsuchiya M, Shaw EA, DiNardo AL, Kaeberlein M, Jarosz DF. 2021. A prion accelerates proliferation at the expense of lifespan. eLife 10:e60917. Other interesting stories: Modified

This episode: Bacteria are able to extract metals from rocks for industrial use, even in microgravity! Download Episode (6.2 MB, 9.0 minutes) Show notes: Microbe of the episode: Decapod ambidensovirus 1   News item   Takeaways As humanity makes progress toward becoming an interplanetary species, consideration is needed on how travelers can survive and thrive in distant places. These methods may look very different from what works well on Earth, with differences in gravity, atmosphere, and access to resources. For example, mining for materials for construction may not be feasible using methods common on Earth. An alternative may be biomining, using microbes that can selectively extract and purify specific metals from minerals.   In this study, the European Space Agency tested the ability of several microbes to extract vanadium from rocks in different gravity conditions, on the International Space Station. Two out of three microbes were able to extract twice as much vanadium as was extracted in the absence

This episode: Bacteria living inside soil fungus produce toxins that can protect their host from tiny predators! Download Episode (7.7 MB, 11.2 minutes) Show notes: Microbe of the episode: Mycobacterium virus DLane Takeaways Soils have many different organisms cooperating and competing for resources. Some little worms called nematodes prey on fungi in the soil, while fungi may effectively defend themselves or strike back with toxins or traps that catch and kill the worms. On top of these interactions are other organisms that interact in various ways. In this study, bacteria living inside a kind of soil fungus produce toxins that defend the fungus against predatory nematodes.   Journal Paper: Büttner H, Niehs SP, Vandelannoote K, Cseresnyés Z, Dose B, Richter I, Gerst R, Figge MT, Stinear TP, Pidot SJ, Hertweck C. 2021. Bacterial endosymbionts protect beneficial soil fungus from nematode attack. Proc Natl Acad Sci 118:e2110669118. Other interesting stories: Sequencing stomach bacteria to find out how pre

This episode: Certain nectar-dwelling bacteria can induce pollen to germinate to access their tasty proteins! Download Episode (6.0 MB, 8.8 minutes) Show notes: Microbe of the episode: Clostridium oceanicum   News item   Takeaways Nectar in flowers seems like it would be a great place for microbes to live, since it has so much sugar, but it's actually somewhat difficult to thrive solely in and on nectar. The carbon in sugar is only one essential element for life, and there's enough of it that it can be overwhelming to the osmotic balance of many microbes. Pollen could provide more nutrients in the form of protein and the nitrogen that comes with it, but it is difficult to penetrate its hard shell.   In this study, certain kinds of bacteria that live in nectar were able to access more pollen protein than other microbes by inducing pollen to germinate, growing out of its shell, or burst and release the protein directly. These microbes only benefited from pollen that were still alive and able to germinate, a

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 int

This episode: A eukaryote has symbionts living in it: green algae and also purple bacteria, a combo never seen before! Download Episode (6.1 MB, 8.8 minutes) 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.

This episode: Training a phage strain on bacteria can increase its ability to control those bacteria for much longer than an untrained phage! Download Episode (5.7 MB, 8.3 minutes) 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 resi

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

This episode: Transplanting microbes from some corals to others could help the corals survive high temperatures! Download Episode (5.7 MB, 8.3 minutes) 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.   Journa

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

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

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

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:

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

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

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