mBiosphere

Bacteriophage are viruses that target a bacterial host for infection. Their specificity is often constrained not only by a particular species, but can also be restricted to infect only a specific strain of that particular species.
Inflammation is a normal part of the host response to bacterial infection. Activation of pathogen recognition receptors leads to cytokine release and the influx of immune cells. Eradicating microbes via inflammation can result in collateral damage: healthy tissues can be damaged by the immune response, but at least the microbial infection is also eliminated. Right?
Ebola hemorrhagic fever is a scary disease. Not only a scary disease to contract and experience, but also a scary disease to survive: news this week has covered the deteriorating condition of the Scottish nurse who survived acute Ebola infection in 2014. Stories of survivors with sudden onset of complications have highlighted how little we know about this disease and those who survive it.
When a Wisconsin state epidemiologist called food microbiologist Kathleen Glass last fall to inquire if she thought caramel apples would be a source of listeriosis, her immediate reaction was no.
Monday, 12 October 2015 15:50

Slo-ing down Streptococcus mutans

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One of my favorite diseases is dental caries. I remember learning, as a wee microbiologist, that cavities were an infectious disease. The idea seemed revolutionary to me at the time. This idea is fairly routine in the world of dentistry nowadays, but it wasn’t always that way.
Global warming (or climate change, if you prefer) doesn't only mean bad things for polar bears. Some immediate implications will hit much closer to readers’ homes (assuming you don’t live at the north pole) and involve much smaller animals.
When a foreign object (such as a microbe) first invades our bodies, there are two broad niches it may land on: wet or dry. The dry option, our skin, allows direct microbial interaction with our cells, though the outermost layer is dead or dying cells that will be lost by desquamation. The wet option, our mucous membranes, is covered by a layer of viscous mucins, glycoproteins, and water (namely, mucus), which acts as a barrier between invading microbes and the underlying cells. Almost anything that isn’t skin – eyes, oral cavity, GI tract, genital tract, lungs – is part of…
Wednesday, 30 September 2015 15:36

Microbiology at the iGEM competition

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How do new scientists learn important skills and concepts? The traditional didactic lecture has fallen out of favor, with students passively listening (or texting in the back) in a top-down knowledge dissemination model. Current curricula utilize several teaching methodologies to engage students both in the classroom and in teaching labs, and there’s no substitute for research as a learning experience. This past weekend, I had the pleasure to attend the 2015 iGEM Giant Jamboree, a team-based molecular cloning biotechnology competition. As a team mentor for several years, I highly recommend this experience as a learning technique for students and team…
Friday, 25 September 2015 15:32

Battling boring beer: new diversity for lagers

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Have you ever brewed beer at home? As a trained yeast geneticist, I felt compelled to at least experience home brewing, and have made dozens of one-gallon brews – amber ales are my favorite. Unfortunately (but probably fortunately for my liver), my small apartment doesn’t facilitate the five-gallon set up that many home-brewers use. But even a gallon’s worth of beer has allowed me to utilize the microbial metabolisms involved in taking a sugar source and turning it into ethanol and other palatable molecules. Brewing is truly one of the best ways to appreciate microbial growth, biochemistry, and a good…
Tuesday, 22 September 2015 15:29

Cerebral Malaria and HIV

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As an infectious diseases physician, Kami Kim says she had long been interested to find the link between HIV and malaria, even if one initially didn’t seem to exist.
Monday, 21 September 2015 15:18

When too much of a good thing is a bad thing

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We’ve discussed the role of cyclic-di-GMP (c-di-GMP) in Pseudomonas biofilm formation on this blog recently. This type of modified nucleotide molecule acts as a second messenger (an amplified product that influences  phenotypes in response to stimuli) in many varied types of bacteria. Cyclic mono- and dinucleotides, such as cyclic AMP (cAMP) and c-di-GMP, are common secondary messengers.
Thursday, 17 September 2015 15:16

Small compound, big implications

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When walking by a pride of lions, I wouldn’t want to wear eau de antelope. Yes, the lions might decide to eat me anyway, but smelling like their favorite food wouldn’t do me any favors. This delicious type of camouflage is what the malaria parasite does after infecting its human hosts: it makes them smell more appealing to nearby mosquitos. The research behind this discovery was published in mBio by Megan Kelly and Dr. Audrey Odom this past spring.
The human microbiome is a collection of all the microorganisms living in association with the human body. This includes bacteria, viruses, eukaryotes, and archaea (single-celled prokaryotic organisms that are not bacteria or eukaryotes). In recent years, the human microbiome has been shown to play a role in various autoimmune diseases; the gut microbiome has been shown to play a role in obesity. Now, new research has demonstrated that the composition of the skin microbiome influences whether a person will clear infection by Haemophilus ducreyi.
Microbes may be single-celled life forms, but they can also work socially, as plenty of research has shown. Social behaviors may involve formation of a reproductive body, forming complex communities, or even altruistic behavior for the sake of the larger population. One of the first observations of social microbial interaction was in the now-famous quorum sensing of Aliivibrio fischeri, in which a bacterial population that has replicated to a certain density will change its gene expression pattern, and thus its behavior – in this case, turning on bioluminescence pathways that allow the colony to glow.
Friday, 11 September 2015 15:03

That'll do, (MRSA-covered) pig

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One of the most pressing scientific problems of our era is antibiotic resistance. After the golden era of antibiotic discovery, liberal use of these drugs in numerous settings has led to regular appearance of antibiotic-resistant outbreaks and 23,000 deaths in the US each year. The situation has become so dire that the President issued an Executive Order today, setting up a task force to revisit regulations of hospital, food, and farm use, calling for standardized practices across hospital settings.
The bacterium that causes cholera, Vibrio cholerae, can grow both aquatically and in a human host. To survive, the bacterium must be able to live in very distinct conditions: imagine how different the temperature, available nutrients, and neighboring microbes are between these two niches. To adapt, V. cholerae must turn on and off the genes appropriate for its current environment. How does the bacterial cell know what its current environment is and which genes it needs?
Wednesday, 26 August 2015 14:56

The anti-HIV properties of breast milk

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One of the most successful battles in the war on HIV has been stemming mother-to-child transmission of the virus. By treating expectant mothers with antiretrovirals that limit the virus numbers in the blood, HIV-infected women are able to have healthy, uninfected babies. However, babies are still susceptible to HIV virions that can be found in breastmilk, and breastfeeding is not recommended for new mothers in the U.S. Since these recommendations were made in the 1990s, infections passed to newborns right after birth have decreased 90% in the U.S.
Roughly 75% of all new, emerging, or re-emerging diseases affecting humans at the beginning of the 21st century are zoonotic diseases, meaning they originated in animals. For the past several years, researchers with the United States Agency for International Development’s PREDICT project have been working to discover and characterize viruses at the wildlife-human interface in order to be better prepared against future epidemics.
We’re approaching the end of summer, and many mBiosphere readers may want to take advantage of the hot weather to go hiking and camping before the chill of autumn sets in. But be prepared – in certain parts of North America, hikers are advised to wear protective clothing to help avoid tick bites, which may carry the causative agent of Lyme Disease, Borrelia burgdorferi. Where did this bacterium come from and why does it infect humans? In Applied and Environmental Microbiology this week, a new review by Dr. Nicholas Ogden et. al. covers the evolutionary and geographical history of Lyme…
Streptococcus species are a natural part of the microflora: its ability to survive under a variety of conditions allow it to colonize several niches on the human body. Some of these species live as mostly harmless commensals, while some of these are potential pathogens that can cause disease under the right circumstances. Group B Streptococcus (GBS), or Streptococcus agalactiae, falls under both categories, as healthy adults rarely present GBS disease symptoms, but those with immunocompromised immune systems – especially the very young and the elderly – can be susceptible to invasive disease.

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