Micro Eclectics

Given a critical change in the environment, how exactly do species adapt?  To find the answer you need controlled experiments and a variable. A team recently did just that to to get at the heart of this evolutionary question, by measuring the growth rates and DNA mutations of 8 different species of Pseudomona s bacteria.  They controlled a single but vital variable during growth, the dose of the antibacterial drug rifampicin, and challenged 480 populations from 8 different strains of Pseudomonas (3840 total) with adapting to the minimal concentration of rifampicin that is needed to completely inhibit the growth of the ancestral strain of each species. They carried out the experiment over 30 generations of bacteria.  Next, the researchers selected 75 randomly chosen rifampicin-resistant mutants from 8 different clonal bacterial strains and sequenced the rpoB gene in all 600 mutants, identifying 47 different mutations. They measured both the growth...

It's hard to have our steak and eat it too. Red meat was once implicated in a wave of studies and linked to heart disease and other maladies, before being absolved. But the microbiome and the surge in advertising for probiotics to promote 'healthy' gut bacteria has implicated red meat again - this time by correlating a nutrient that the authors say is changed by gut bacteria into an atherosclerosis-causing metabolite, which means hardening of the arteries. Writing in Cell Metabolism , Dr. Stanley Hazen, of the Cleveland Clinic and colleagues implicated a bacteria in the gut that converts L-carnitine, a nutrient abundant in red meat, into a compound called trimethylamine, which in turn changes to a metabolite named trimethylamine-N-oxide (TMAO), which promotes atherosclerosis. Now they believe another metabolite, called gamma-butyrobetaine, is generated to an even greater extent by gut bact...

The adult human body is made up of about 37 trillion cells. Microbes, mainly bacteria, outnumber body cells by 10 to 1. This huge community of microbes, called the microbiome, affects the health, development and evolution of all multicellular organisms, including humans, according to the latest craze in health supplement marketing and plenty of science papers latching onto the fad. Symbiotic microbes can help prevent infection by disease-causing pathogens but sometimes the interaction goes the other way, with a pathogen or disease disrupting the normal community of symbiotic bacteria. In a new paper in the Proceedings of the National Academy of Sciences , a team of scientists from UC Santa Barbara say that a fungal pathogen of amphibians does just that. Experiments with model organisms such as mice have shown that infectious pathogens can disrupt the "normal" microbiome, but the extent to which this p...

Archaea are a family of single-celled organisms that can thrive in environments like boiling hydrothermal pools and smoking deep sea vents deep underground, which are too extreme for most other species to survive. Until the late 1970s, biologists thought that Archaea were just weird bacteria, but then a landmark analysis of their DNA showed that they represent an independent branch on the tree of life that stretches back more than three billion years.  Now they may be a new source of antibacterial drugs.  Researchers have discovered a functional antibacterial gene in Archaea  The realization that Archaea could be a source of novel pharmaceuticals emerges from a study of widespread horizontal gene transfer between different species conducted by a team of scientists from Vanderbilt University and Portland State University in Oregon. The researchers were investigating a gene that produces a type of enzyme found in tears, saliva, milk and mucu...

Yeast cells can sometimes reverse the protein misfolding and clumping associated with diseases such as Alzheimer's, according to new research which contradicts the idea that once prion proteins have changed into the shape that aggregates, the change is irreversible. Prions are proteins that change into a shape that triggers their neighbors to change, also. In that new form, the proteins cluster. The aggregates, called amyloids, are associated with diseases including Alzheimer's, Huntington's and Parkinson's. For yeast, having clumps of amyloid is not fatal. In a new study, researchers exposed amyloid-containing cells of baker's yeast to 104 F (40 C), a temperature that would be a high fever in a human.  When exposed to that environment, the cells activated a stress response that changed the clumping proteins back to the no-clumping shape. The finding suggests artificially inducing stress responses may one day help develop treatments for diseas...

Microbiologists rarely wash their jeans. The reason is because they know how to keep the color looking new without getting odors - they freeze their pants.  Freezing can even work in more extreme scenarios, like with waste water.  When waste water freezes, it is purified through the formation of a cleaner layer of ice. Then the clean layer of ice can be removed from the rest of the waste water, and the remaining waste water is more concentrated, which can be treated as needed with a lot less outside processing. Energy is required only for breaking the ice and transporting it from the waste water pool. Credit: Lappeenranta University of Technology, LUT The most practical application is leaving waste water from mines to freeze in special pools and then removing the cleaner part by breaking the ice. Then the treated waste water would be recycled, or undergo further treatment using membrane filtration, reducing the amount of fresh water that is us...

Bacteria communicate using chemical signals and now scientists have described a previously unknown communication pathway that appears to be widely distributed - and even leads to pathogens. The investigation of bacterial communication is valuable because those pathways are a possible therapeutic target for new medicines. If the relevant communication options are prevented, the bacteria cannot develop their pathogenic properties. Different types of bacteria also have different methods of communication. A team led by Dr. Helge B. Bode, a Merck-endowed professor for molecular biotechnology at the Goethe University in Frankfurt, and Dr. Ralf Heermann from the department of microbiology at the Ludwig Maximilian University in Munich, had already discovered a new bacterial communication pathway in 2013. Now they have succeeded in decoding a further new and widely distributed chemical type of bacterial communication. To date, the best known communication between bacteria oc...

Every summer, there are reports linking a bacterium called Vibrio vulnificus to people getting sick or dying. The bacteria are found in warm saltwater and problems occur after eating raw tainted shellfish or when an open wound comes in contact with seawater. People with a weakened immune system, chronic liver disease or iron overload disease are most at risk for severe illness. Vibrio vulnificus infections in high-risk individuals are fatal 50 percent of the time. Now, researchers at UCLA have figured out why those with iron overload disease are so vulnerable. People with the common genetic iron overload disease called hereditary hemochromatosis have a deficiency of the iron-regulating hormone hepcidin and thus develop excess iron in their blood and tissue, providing prime growth conditions for Vibrio vulnificus. A microscopic look at Vibrio vulnificus bacteria swimming around. Credit: Paul Gulig/University of Florida The study also found that minihepcidin, a medi...

We have beneficial bacteria because of symbiosis: the success of the host determines the survival and spread of the microbe. But if bacteria grow too much they may become deadly. In a new study, a research team from Instituto Gulbenkian de Ciencia found that a single genomic change can turn beneficial bacteria into pathogenic bacteria, by boosting bacterial density inside the host. Ewa Chrostek and Luis Teixeira studied the symbiosis between a fruit fly (Drosophila melanogaster) and the bacterium Wolbachia to answer how benign bacteria become pathogenic. Wolbachia is present in most insect species and protects some of them against viruses, including the dengue fever virus.  Previous studies conducted by Luis Teixeira's team showed that the number of Wolbachia inside the fruit fly determines its effect on the host. Bacteria that reach very high levels inside the fly become harmful. Hence, this research team set out to investigate the genetic basis that contr...

Just about everyone in the developed world has taken an antibiotic to treat a bacterial infection and the instructions are well-known; don't stop after you start to feel better, even though you know they are killing machines. Yet the picture may be more complex, according to a new paper, and it might change our understanding of why bacteria produce antibiotics in the first place.  "For a long time we've thought that bacteria make antibiotics for the same reasons that we love them - because they kill other bacteria," said  Elizabeth Shank, an assistant professor of biology at University of North Carolina at Chapel Hill. "However, we've also known that antibiotics can sometimes have pesky side-effects, like stimulating biofilm formation."  Shank and her team now show that this side-effect - the production of biofilms - is not a side-effect after all, suggesting that bacteria may have evolved to produce antibiotics in order to p...

Oats are often touted for lowering bad cholesterol,  improving the immune system, lowering blood pressure and, more recently, being gluten-free, but a new study finds that some oat-based breakfast cereals in the U.S. contain a mold-related toxin called ochratoxin A (OTA) that's been linked to kidney cancer in animal studies.  Natural or not, they may need closer monitoring for potential mold contamination, warns a paper in the Journal of Agricultural and Food Chemistry .  Dojin Ryu and Hyun Jung Lee note that ochratoxin A is one of the most common toxic products released by molds in the world. Previous studies have found the toxin in samples of pork, dried fruits, wine, coffee and other products. Scientists don't yet know how the toxin affects human health, but the International Agency for Research on Cancer, which is part of the World Health Organization, classifies it as a possible human carcinogen.  Animals exposed to ochrato...

Viruses that invaded the DNA of humanity's ancestors millions of years ago may now play critical roles in the earliest stages of human development, researchers say. The discovery sheds light on the key part that viruses may have played in human evolution, scientists added. The early stages of embryonic development lay the foundation of what become the organs and tissues of an organism. Past research had revealed that a host of factors can influence early human development, such as the diets and environments of parents. Now researchers find that viruses incorporated into the human genome may be another major factor. Viruses infect cells in order to hijack their machinery and make copies of themselves. One type of virus known as a retrovirus does this by weaving its own genes into the DNA of its hosts. The most infamous retrovirus is HIV, the virus that causes AIDS. In rare instances, retroviruses infect sperm or egg cells. If those cells go on to become part...

There is microbiology and then there is micro-micro-microbiology. The existence of ultra-small bacteria has been debated for decades, but now there is comprehensive electron microscopy and DNA-based evidence of the elusive microbes that are about as small as life can get.  The cells have an average volume of 0.009 cubic microns (a micron is one millionth of a meter). About 150 of these bacteria could fit inside an Escherichia coli cell and more than 150,000 cells could fit onto the tip of a human hair.  The diverse bacteria were found in groundwater and are thought to be quite common. They're also quite odd, which isn't a surprise given the cells are close to and in some cases smaller than several estimates for the lower size limit of life. This is the smallest a cell can be and still accommodate enough material to sustain life. The bacterial cells have densely packed spirals that are probably DNA, a very small number of ribosomes, hair-like appendag...

In parts of the country that do not have icebergs washing up on shore or falling from the sky, it is almost spring planting season.  For tomatoes, that mean unless you use a toxic organic or synthetic chemical, there is a chance of bacterial infection, leading to stunted growth and less nutritional value. The discovery of new regulations of defense pathways for plants could lead to helping those home-grown tomatoes fight off certain bacteria better and even have implications for pear trees, roses, soybeans and rice. Tomatoes infected with speck disease often have wilted leaves and damaged fruit. Credit: University of Missouri "Each year, millions of dollars are lost from damage to crops and ornamental plants caused by pathogens, which include a bacteria known as Pseudomonas Syringae," said Antje Heese, assistant professor of biochemistry at MU. "This bacteria directly affects tomatoes and causes speck disease that permanently damages the frui...

Antibiotic resistance is poised to spread globally among bacteria frequently implicated in respiratory and urinary infection, according to new research. A recent study shows that two genes that confer resistance against a particularly strong class of antibiotics can be shared easily among a family of bacteria responsible for a significant portion of hospital-associated infections. Drug-resistant germs in the same family of bacteria recently infected several patients at two Los Angeles hospitals. The infections have been linked to medical scopes believed to have been contaminated with bacteria that can resist carbapenems, potent antibiotics that are supposed to be used only in gravely ill patients or those infected by resistant bacteria. The researchers studied a family of bacteria called Enterobacteriaceae, which includes E. coli, Klebsiella pneumoniae and Enterobacter. Some strains of these bacteria do not cause illness and can help keep the body healthy. But i...

Methicillin-resistant Staphylococcus aureus (MRSA), an antibiotic-resistant superbug, can cause life-threatening skin, bloodstream and surgical site infections or pneumonia - a new reports finds that cigarette smoke may make things even worse. "We already know that smoking cigarettes harms human respiratory and immune cells, and now we've shown that, on the flipside, smoke can also stress out invasive bacteria and make them more aggressive," said senior author Laura E. Crotty Alexander, MD, assistant clinical professor of medicine at UC San Diego and staff physician at the Veterans Affairs San Diego Healthcare System. Crotty Alexander is a pulmonologist who sees many patients who smoke cigarettes. She also sees many MRSA infections, and that got her wondering if one might influence the other. To test the hypothesis, Crotty Alexander and her team infected macrophages, immune cells that engulf pathogens, with MRSA. Some of the bacteria were grown normally...

A new study shows that the microbial communities we carry in and on our bodies, the human microbiome, contain the potential to uniquely identify individuals, much like fingerprints.  Researchers and demonstrated that personal microbiomes contain enough distinguishing features to identify an individual over time from among a research study population of hundreds of people. The study, the first to rigorously show that identifying people from microbiome data is feasible, suggests that we have surprisingly unique microbial inhabitants, but could raise potential privacy concerns for subjects enrolled in human microbiome research projects. They used publicly available microbiome data produced through the Human Microbiome Project (HMP), which surveyed microbes in the stool, saliva, skin, and other body sites from up to 242 individuals over a months-long period. The authors adapted a classical computer science algorithm to combine stable and distinguishing sequence...

The bacteria that sneak past the brain's defenses to cause deadly bacterial meningitis are clever adversaries - they convince their host that they are harmless yet then have freedom to cause disease by taking advantage of a molecular warning signal and inducing the brain's cellular armor to temporarily break down, letting in the bacterial horde. The blood-brain barrier is a thin network of blood vessels whose cells abut each other very closely, forming protein junctions too tight for bacteria and viruses to fit through. The barrier's purpose is to prevent unwanted material from crossing over from the surrounding bloodstream into brain tissue. "You can think of the blood-brain barrier as a brick wall," explains Brandon Kim, a biology graduate student at San Diego State University. "Each cell of the blood-brain barrier is a brick and these tight junctions are the mortar." Like castle guards, the cells that form this barrier can selectiv...

Hope you washed your hands. n4i , CC BY A recent eye infection suffered by 18-year-old Nottingham University student Jess Greaney is the kind of story that fills us with horror. Greaney had keratitis, an inflammation of the cornea, caused by Acanthamoeba castellanii , a parasite that was living and feasting on her eye. A. castellanii is a ubiquitous organism, found in many eco-systems worldwide. It is able to survive in harsh environmental circumstances – even in some contact lens solutions – and this is not the first occurrence of A. castellanii appearing in the eye. Acanthamoeba keratitis (AK) is a neglected malady frequently associated with contact lens wear and it is thought Greaney caught the bug after splashing tap water on her contact lenses . Not a great friend to have Acanthamoeba infection of the cornea causes severe inflammation, intense pain and impaired vision, which is blinding if left untreated . Infection begins when the para...

Antibiotic-resistant bacteria are on the rise and they pose a global threat to public health. Common antibiotics are often ineffective in treating infectious diseases because pathogens acquire resistance genes. These antimicrobial resistance genes are obtained in different ways. There are different explanations for how resistances are transferred and a now study found phages - viruses that exclusively infect bacteria - in chicken meat that are able to transfer antimicrobial resistance to bacteria.  Phages do not directly pose a risk to humans because they can only infect bacteria. No other cells or organisms can be infected.  Researchers isolated phages from 50 chicken samples purchased from Austrian supermarkets, street markets and butchers. They found phages in 49 samples. Their analysis showed that one quarter of the phages under study were able to transduce antimicrobial resistance to E. coli bacteria under laboratory conditions. Th...

Bacteria and viruses have an obvious role in causing infectious diseases, but microbes have also been identified as the surprising cause of other illnesses, including cervical cancer (Human papilloma virus) and stomach ulcers (H. pylori bacteria). A new study by University of Iowa microbiologists now suggests that bacteria may even be a cause of one of the most prevalent diseases of our time - Type 2 diabetes. The research team led by Patrick Schlievert, PhD, professor and DEO of microbiology at the UI Carver College of Medicine, found that prolonged exposure to a toxin produced by Staphylococcus aureus (staph) bacteria causes rabbits to develop the hallmark symptoms of Type 2 diabetes, including insulin resistance, glucose intolerance, and systemic inflammation. "We basically reproduced Type 2 diabetes in rabbits simply through chronic exposure to the staph superantigen," Schlievert says. The UI findings suggest that therapies aimed at eliminating staph bacteria or...