In June 2015, mBioblog became mBiosphere, expanding its scope to all of the research journals published by the American Society of Microbiology. To commemorate the end of the year, we’d like to highlight our most popular stories since the switch. The below stories are fifteen of the top stories from 2015 (post-mBiosphere) – how many do you remember?
Viruses depend on cellular machinery to make their progeny virions, and must get inside their host cells to access this machinery. Research published in June showed that hantaviruses rely on membrane cholesterol to get inside cells. Gene depletions in cholesterol biosynthesis and metabolism were required for hantavirus infection. These findings might lead to cholesterol-manipulating therapeutics to treat these diseases.
How do patients become susceptible to Clostridium difficile infections? A July study suggested the answer is context-dependent, based on the complex makeup of the gut microbiome. A mathematical model based on patient data was accurate for retrospective predictions, and may someday be used in predicting which patients are at risk.
July also featured a study of the CF lung using nontraditional techniques. Using environmental chemistry techniques to measure the lung conditions at microscale resolution, researchers found the microbiologic environment to be much more heterogeneous than previously understood. Sputum differed largely between patients and within a single patient, and parts of the sputum were largely anoxic, and even contained hydrogen sulfide. Understanding the metabolic survival strategies in these conditions may lead to new therapies to treat these infections.
Several incidents in 2015 highlighted still-existent gender equality problems in science. One promising study, published in August, laid out a promising roadmap toward promoting equal representation in scientific presenters among conference-goers. With data to endorse it, a plan including both awareness and direct intervention was enacted over the past three ASM General Meetings, with an improved ratio of men and women speakers.
One of the hurdles in generating biofuel from plant materials is in the high energetic (and financial) cost of degrading lignocellulose material in the plant cell wall. An August study characterized a new tungsten-dependent oxidoreductase in the thermophile Caldicellulosiruptor bescii. The highly-expressed enzyme has an unknown substrate, which, once discovered, may help scientists design better biofuel systems.
Part of what makes Vibrio cholerae deadly is its ability to withstand intestinal bile salts, which kill or inhibit other microbes. How does the bacterium interpret environmental signals to turn on its bile defenses? An August study focused on the signals detected and the subsequent gene expression changes. This study showed a known toxin regulator, ToxR, can also regulate bile resistance, broadening the known effects of this important regulatory protein.
Regardless of the niche size, environmental factors influence population selection. This was demonstrated in two papers covering different scales of niche: one, the global lineages of Cryptococcus gattii, and the other, a the populations of Pseudomonas aeruginosa in a single patient over a year. Both studies used whole-genome sequencing to track population evolution over time, and highlighted pressures that lead to natural selection.
Drug-resistant microbial infections are increasing in hospitals worldwide. A new section in Antimicrobial Agents and Chemotherapy, called “Challenging Clinical Cases of Antimicrobial Resistance,” uses clinical cases as teaching opportunities. An interview with Dr. Cesar Arias discusses the origin and potential application of this column as a way to improve patient care.
One of our bodies’ first line of defenses is the barrier to the outside world, where microbes are blocked or sequestered by our skin and mucus membranes. An October study showed that not all mucus is equally protective, and that its protective properties are influenced by the microbes present. Cervicovaginal mucus protection is changed by different species of Lactobacilli in the vaginal microbiome – which may leave those with less protective flora susceptible to invaders.
After being engulfed by a macrophage, microbes will still try to avoid elimination. If macrophage cells can’t kill bacteria, they may undergo autophagy, sacrificing themselves to also kill their intracellular bacteria. An October article demonstrated that the bacterium Pseudomonas aeruginosa isn’t killed by autophagy, and sometimes will induce autophagy to escape a macrophage cell after phagocytosis.
A rare but deadly bacterium can contaminate baby formula. Cronobacter sakazakii causes up to 40% infant mortality in rare but fatal outbreaks. Formula treatment with a newly described bacteriophage may prevent outbreaks.
What happens when a patient takes a prescribed course of antibiotics? A new study showed there is a long-lasting effect on the microbiome – effects on the gut microbiome composition were seen as long as a year after taking antibiotics. Interestingly, hardly any changes were noticed in the oral microbiome. Discovering how these drugs affect only particular niches may protect patients from off-target antibiotic effects in the future.
Microbial fermentation has always been an important part of cocoa pulp preparation, but food scientists are hoping to increase microbial influence on chocolate flavor. Some Saccharomyces cerevisiae strains are heat-tolerant and some are heavy producers of flavorful metabolites. A hybrid of these two is able to outcompete natural fermenters and may lead to a systematic way to flavor chocolate.
The faster clinical microbiologists can identify the drug resistance profile of an infection, the more quickly doctors can administer proper medication. New advances in mass spectrometry gather information that allows simultaneous identification of microbial infections and detection of certain beta-lactamases. The technique has been verified for clinical application and may already be in use at diagnostic labs.
Just before Christmas, ASM introduced the latest journal to its research publication portfolio. mSystems aims to publish systems-related microbial sciences at the population, culture, and cellular level. An opening editorial and three research articles kick off its inaugural online publication.
In the broad field of microbiology, there is always new research in clinical, environmental, and agricultural microbial sciences. Was your favorite story covered this year? What was your most memorable microbiology moment in 2015? Please leave your comments with features you hope to see covered more heavily as mBiosphere continues.
Happy New Year to mBiosphere readers everywhere! Let's see what new discoveries 2016 will bring!
-- Julie Wolf