Symbiotic algae that live within reef-forming corals scoop up available nitrogen, store the excess in the form or uric acid crystals, and slowly feed it to the coral as needed, according to a study in mBio this week. Scientists have known for years that these symbiotic microorganisms serve up nitrogen to their coral hosts, but this new study sheds light on the dynamics of the process and reveals that the algae have the ability to store excess nitrogen, a capability that could help corals cope with the ups and downs of nitrogen concentrations in the environment. "It was a great... Continue reading

To infect its host, the respiratory pathogen Pseudomonas aeruginosa takes an ordinary protein usually involved in protein synthesis and adds three small molecules to turn it into a key virulence factor according to a study in mBio this week, economically employing one protein in two different ways. Scientists at Emory University School of Medicine, the University of Virginia, and Universidad de las Islas Baleares in Mallorca, Spain, uncover this previously unknown virulence factor in P. aeruginosa, one of the most common causes of hospital-acquired pneumonia. How is EF-Tu like a spork? P. aeruginosa uses it for two purposes: protein synthesis... Continue reading

Researchers at NIAID have devised a method for delivering tumor cell-killing enzymes in a way that protects the enzyme until it can do its work inside the cell. In their study in mBio this week, researchers assembled microscopic protein packages that can deliver an enzyme called PEIII to the insides of cells. By attaching a protein called ubiquitin to the enzyme, they were able to protect the PEIII from degradation by the cell, allowing the PEIII to complete its mission of cell assassination. The results indicate that ubiquitin may be a useful addition to targeted toxins, therapies that specifically target... Continue reading

"Like rolling back a rock and seeing the ecosystem change," says the lead author of a study in mBio this week. It's a classical experiment in grade school ecology, except that the ecosystem in question is the microbiome of the human penis. And the "rock" is the foreskin, removed in adulthood for the sake of preventing HIV infection. In the study, Liu et al. show that circumcision drastically alters the microbiome of the penis, changes that could explain why circumcision offers protection against HIV and other viral infections. Researchers from the Translational Genomics Research Institute (TGen) and other institutions studied... Continue reading

Who knew frozen mice could be so useful? Mouse viruses discovered in a bank of frozen rodents could pave the way for future progress in hepatitis research, enabling scientists to study human disease and vaccines in the ultimate lab animal. In mBio this week, authors from Colombia University and elsewhere describe their search for viruses related to the human hepatitis C virus (HCV) and human pegiviruses (HPgV) in freezer stocks of wild mice. The discovery of several new species of hepaciviruses and pegiviruses that are closely related to human viruses suggests they might be used to study these diseases and... Continue reading

Luminescent bacterial symbionts inside squids use light and chemical signals to control circadian-like rhythms in the animals, according to a study to in mBio this week. The Hawaiian bobtail squid, Euprymna scolopes (left), houses a colony of Vibrio fischeri bacteria in its light organ, using the bacteria at night as an antipredatory camouflage while it ventures out to hunt. Testing with defective V. fischeri symbionts that lack the ability to make light and with squids that lack symbionts altogether shows that, in addition to acting as a built-in lamp, V. fischeri also controls when the squid expresses a gene that... Continue reading

A Commentary in mBio today takes issue with a recent study of research misconduct among life scientists. Molly Carnes and her coauthors say the data may not be as straightforward as they appear at first blush, and that we shouldn't be too quick to condemn men for activities that hew close to gender stereotypes. In their analysis published in January, Fang et al. say data from the Office of Research Integrity indicates male researchers funded by the Department of Health and Human Services commit research misconduct more often than their female peers, a gender disparity that is most pronounced among... Continue reading

Humans don't make chitin. So why do many bacterial pathogens require chitinases to maintain an infection? A study in mBio this week reveals that in Listeria monocytogenes, at least, chitinase helps the environmental pathogen live a double life, digesting chitin while the bacterium lives in the soil and attacking the innate immune system when it makes its way into the human host. This is the first study to demonstrate chitinase activity against a specific host immune response, say the authors. The fact that chitinase is involved in the pathogenicity of certain environmental pathogens has been known for a while. Chitin... Continue reading

Geobacter's pili conduct electrons along their length using the rings on aromatic amino acids, according to a study in mBio this week. Contrary to all other known forms of biological electron transport, in which electrons are carried by discrete entities and passed from one to another, Geobacter's pili have a core of aromatic amino acids that turn these hair-like appendages into functioning electron-carrying biological wires, adding credence to a controversial idea in biology. "It's the aromatic amino acids that make it a wire," says lead author Derek Lovley. Lovley and his colleagues developed a strain of Geobacter, Aro-5, that lacked... Continue reading

It may well be snowing where you live, but if you're in the Northern Hemisphere, spring isn't far off. Spring means flowers. And what is a flower to a microbiologist? It's a niche. Yes, flowers are a microbial habitat like any other, and though they start out with few microbial members, these communities quickly acquire a broad range of microbial types and progress through a classical succession of different groups. In mBio this week, Shade et al. describe the unexpectedly great microbial diversity of apple blossoms, communities marked by the consistent presence of groups that are well-known for their abilities... Continue reading

Offense or defense? Quorum sensing has been tied to a number of bacterial functions, many of them involving virulence, but could quorum sensing also be used in defense? In mBio this week, there's new evidence that E. coli uses quorum sensing to trigger an antiphage mechanism that defends against at least two very different types of phage. In evading phages, timing is everything. There are any number of ways for a bacterium to defend itself, but the benefits of evading an attack have to be weighed against the metabolic costs or readiness, so it makes sense to set up defenses... Continue reading

The new coronavirus that has emerged in the Middle East is well-adapted to infecting humans but could potentially be treated with immunotherapy, according to a study in mBio this week. The HCoV-EMC and SARS-CoV Replicating within human cells study indicates that the virus HCoV-EMC can penetrate the bronchial epithelium and evade the innate immune system as easily as a cold virus can, signs that HCoV-EMC is well-equipped for infecting human cells. The study also reveals that the virus is susceptible to treatment with interferons, immune proteins that have been used successfully to treat other viral diseases, opening a possible mode... Continue reading

Epigenetic controls like histone modification and chromatin remodeling play important regulatory roles in all cellular processes requiring access to the genome. So when a herpes simplex virus or varicella-zoster virus infects a human cell, one of the first things it does is attack the cell’s epigenetic modifications so it can gain access to a chromosome. Once these epigenetic controls are down, the lytic process can begin. In mBio this week, scientists from NIAID and elsewhere found a way to suppress the herpes virus’ ability to alter these epigenetic controls. An important part of the lytic replication cycle, viral protein LSD1... Continue reading

Bacteria and fungi: are they friends of foes? In the case of Pseudomonas aeruginosa and Candida albicans, they’re definitely foes. A study in mBio this week reveals that P. aeruginosa puts the kibosh on C. albicans' growth by altering the fungus’ respiratory activity. C. albicans and P. aeruginosa are often found together in the lungs of patients with cystic fibrosis, so you can imagine they either compete for resources or help each other maintain their respective niches (or both?). In mixed culture, P. aeruginosa forms a biofilm and basically smothers C. albicans filaments, eventually killing the hypha. C. albicans, in... Continue reading

Iron oxidizing bacteria aren’t exactly rare, but they’re hard to study in the lab because of the copious amounts of oxidized iron (Fe(III)) they produce. In mBio this week, a group at the University of Minnesota – Twin Cities describes a new method for growing iron-oxidizing bacteria Reactor for growing iron oxidizers. No orange slime in sight... using a steady flow of electrons, an advance that will allow them to better study the organisms. It also opens the possibility that one day electricity generated from renewable sources like wind or solar could be funneled to iron oxidizing bacteria that combine... Continue reading

It’s not hard to see that men are more likely to engage in risky behaviors than women, or that crime rates are many times higher among men, but this tendency to break the rules also extends to male scientists, according to a study in mBio this week. An analysis of data from the Office of Research Integrity reveals that men commit research misconduct more often than their female peers, a gender disparity that is most pronounced among senior scientists. In their study in mBio, co-authors Ferric C. Fang of the University of Washington School of Medicine in Seattle, Joan W.... Continue reading

Is the new coronavirus the next SARS? A Commentary in mBio comes on the same week scientists are convening at a WHO meeting in Cairo to share information about the novel coronavirus that is causing alarm in the public health community. In their Commentary, Stanley Perlman and Jincun Zhao of the University of Iowa discuss the recent work of Muller et al., delving into important details about the virus’ receptor on human cells and its troubling ability to infect numerous different species. In December, Muller et al. revealed that the new coronavirus, called HCoV-EMC, does not share the same receptor... Continue reading

In mBio this week, a new study offers hope for a vaccine against group A Streptococcus (GAS). GAS is familiar to most of us as the cause of Strep throat, but it’s more than that. It’s also the cause of some Predicted Structure of streptolysin O serious and invasive infections, including septic arthritis, impetigo, and necrotizing fasciitis, so a vaccine for group A Strep (GAS) could not only keep Strep-throat-prone kids in school, it could potentially spare a great deal of human suffering. The study in mBio follows up on earlier work that found the GAS protein streptolysin O was... Continue reading

This week in mBio: A (surprisingly small) team of researchers have sequenced the genome of the fungus Pneumocystis jirovecii, an advancement that could help identify new targets for drugs to treat and prevent Pneumocystis pneumonia, a common and often deadly infection in immunocompromised patients. The organism cannot yet be isolated and grown for study in the lab, so details about Pneumocystis pneumonia, the biology of P. jirovecii, and its pathogenicity are hard to come by. The genome sequence represents a wealth of new information for doctors and researchers tackling this disease. Pneumocystis pneumonia is an opportunistic infection that strikes most... Continue reading

Scientists trying to put HIV-prevention methods in the hands of women have been disappointed so far in their efforts with vaginal microbicides. In the lab, in vitro testing of microbicides like nonoxynol-9, and cellulose sulfate have produced promising results, but when subjected to clinical trials, each of these compounds has failed miserably. Not only do nonoxynol-9, and cellulose sulfate fail to protect against HIV infection, when a woman uses the stuff frequently she actually has an increased risk of HIV infection. Why the tragic paradox? Do microbicides like these change the vaginal microbiome? The authors of a paper in mBio... Continue reading

A few decades ago, emerging infectious diseases were not the subject of interest they are today. What put them on the map, in part, was the AIDS epidemic, a disease that seemingly came out of nowhere and grabbed the international spotlight overnight. But a 1992 report from the Institute of Medicine that highlighted the from threat new diseases also played a significant role, write David Morens and Anthony Fauci of the NIAID this week in mBio. The IOM report spurred institutional progress and research advances, they write, and today we see a very different lansdscape in emerging infections, one marked... Continue reading

The SARS epidemic of 2002-2003 was short-lived, but the new human coronavirus that is alarming public health authorities can infect cells from humans and bats alike, a fact that could make the animals a continuing source of infection, according to a study to be published in mBio today. The new coronavirus, called hCoV-EMC, is now blamed for five deaths and several other cases of severe disease originating in countries in the Middle East. According to the new results, hCoV-EMC uses a different receptor in the human body than the SARS virus, and can infect cells from a wide range of... Continue reading

The adaptive immune system known as CRISPR-Cas (clustered regularly interspaced short palindromic repeats and CRISPR-associated genes) is found in 90% of fully sequenced thermophiles, but in less than 50% of mesophilic bacteria. Why the discrepancy? In their study in mBio this week, researchers from Harvard Medical School and from the National Center for Biotechnology Information at NIH used a computer model to sort this out. The upshot? When viruses mutate quickly, as they do at middle-of-the-road temperatures, they can overwhelm CRISPR-Cas systems. CRISPRs in bacteria and archaea use “spacers”, DNA sequences that are designed based on a viral or plasmid... Continue reading

New clues about the evolution and ecology of Borellia burgdorferi could point the way to a vaccine for immunizing white-footed mice against the bacteria, according to a study in mBio this week. The study sheds some light on how the immune system of the white-footed mouse responds differently to different strains of the bacterium and could help vaccine developers find ways to immunize the animals against infection. The white-footed mouse is a very common natural reservoir for Lyme-causing bacteria, so a vaccine that keeps these wild mice free of the pathogen could significantly curb the spread of the disease from... Continue reading

In mBio this week there's some interesting news about horizontal gene transfer on surfaces. E. coli and Klebsiella strains with antibiotic resistance genes not only survive for weeks on dry stainless steel surfaces, they share their resistance genes instantly. But put those same bacteria on a copper alloy surface? “Rapid death, inhibition of respiration, and destruction of genomic and plasmid DNA of both pathogens,” write the authors. They conclude, "The use of copper alloys in clinical and community settings could help reduce infection spread and also reduce the incidence of horizontal transmission genes conferring drug resistance, virulence, and pathogenesis and... Continue reading