A surprisingly specific genetic portrait of the ancestor of all living things has been generated by scientists who say that the likeness sheds considerable light on the mystery of how life first emerged on Earth.
This venerable ancestor was a single-cell, bacterium-like organism. But it has a grand name, or at least an acronym. It is known as Luca, the Last Universal Common Ancestor, and is estimated to have lived some four billion years ago, when Earth was a mere 560 million years old.
The new finding sharpens the debate between those who believe life began in some extreme environment, such as in deep sea vents or the flanks of volcanoes, and others who favor more normal settings, such as the “warm little pond” proposed by Darwin.
Bacteriophages, little-used for decades in the U.S. and much of Europe, are gaining new attention because of resistance to antibiotics
NANTES, France—A hospital nurse soaked a bandage in a colorless liquid containing viruses drawn from a toxic sewer in Paris, a well in Mali and a filthy river in India. Then she daubed it gently on an elderly woman’s severely burned back.
“It’s healing,” said Ronan Le Floch, the doctor overseeing the burned woman’s care. The painful wound’s greenish tinge, the telltale sign of a potentially deadly bacterial infection, had vanished.
The liquid treatment was a cocktail of about one billion viruses called bacteriophages, which are the natural-born killers of bacteria. Little known among doctors in the West, phages have been part of the antibacteria arsenal in countries of the former Soviet Union for decades.
Doctors in the U.S. and much of Europe stopped using phages to fight bacteria when penicillin and other antibiotics were introduced in the 1940s. Now, though, Western scientists are turning back to this Stalin-era cure to help curb the dramatic growth of bacterial resistance to antibiotics.
Modern disease theory must account for communities of commensal bacteria.
At the turn of the last century, German physician Heinrich Koch identified four critical criteria for determining whether or not a particular microbe causes a disease. The ideas behind them were crucial for advancing medicine and formalizing the germ theory of disease. Over the last century, these postulates have been updated as medicine has advanced.
In what may end up being the most recent of these updates, biologists Allyson Byrd and Julia Segre propose some adjustments to these classic medical postulates intended to bring them in line with analytic techniques based on DNA sequencing and the most current understanding of bacterial communities. Just as the previous updates to Koch’s postulates did, these proposed amendments incorporate cutting-edge scientific knowledge and add nuance to our understanding of the causes of disease.
Koch’s original postulates are that, if a microorganism causes a disease, then:
For every single case of the disease, the microorganism will be present.
Healthy people will not carry the microorganism—if they did, they would be sick.
The microorganism can be isolated and cultured in a lab, then used to infect new people.
The microorganism can be re-isolated from a person who was experimentally infected.
Since his discovery in 1991, Ötzi the “Iceman” — an intact, naturally mummified man believed to have lived in the Italian Alps approximately 5,300 years ago — has captured the international imagination and provided a tantalizing glimpse into life during the Copper Age.
Now, a new research project, which analyzed the genetic composition of bacteria in the Iceman’s stomach, is giving scientists insight into not only the Iceman’s personal life, but the history of human geography at large.
The scientists, who published their study in the journal Science on Thursday, focused on a type of common bacteria called Helicobacter pylori, or H. pylori. Found in about two thirds of the world’s population, according to the National Institutes of Health, it usually inhabits the stomach and is capable of causing infections that can lead to ulcers or even stomach cancer.
A newly identified gene that renders bacteria resistant to polymyxin antibiotics—drugs often used as the last line of defense against infections—has the potential to be shared between different types of bacteria. The finding raises concern that the transferable gene could make its way into infectious bacteria that are already highly resistant to drugs, thereby creating strains of bacteria immune to every drug in doctors’ arsenal.
The gene, dubbed mcr-1, exists on a tiny, circular piece of DNA called a plasmid. These genetic elements, common among bacteria, are mobile; bacteria can make copies of them and share them with whatever bacteria happens to be nearby. Though scientists have previously discovered genes for polymyxin resistance, those genes were embedded in bacterial genomes, thus were not likely to easily spread.
Scientists discover a novel antibacterial molecule that targets a vital RNA regulatory element.
Researchers at the pharmaceutical company Merck have identified a new bacteria-killing compound with an unusual target—an RNA regulatory structure called a riboswitch. The team used its drug, described in Nature today (September 30), to successfully reduce an experimental bacterial infection in mice, suggesting that the molecule could lead to the creation of a new antibiotic. Moreover, the results indicate that riboswitches—and other RNA elements—might be hitherto unappreciated targets for antibiotics and other drugs.
“Finding an antibiotic with a new target . . . has always been one of the holy grails of antibiotics discovery,” said RNA biochemist Thomas Hermann of the University of California, San Diego, who was not involved in the work. “It looks like that’s what the Merck group has now accomplished.”
Allergic to penicillin? Then you could be shot full of something that came out of a Sardinian sewer. Here’s the backstory of the important medicine that we found floating around in our own feces.
Typhoid fever is a life-threatening sickness. Although it’s rare in areas with good drinking water purification systems, worldwide it claims 200,000 lives every year. Even when scientists found out that the fever was the result of a bacterial infection, usually picked up through contact with sewage already containing the bacteria, direct treatments were hard to come by, and there was little they could do to purify water supplies for entire regions.
This is why Giuseppe Brotzu, an Italian professor of hygiene, was so surprised that the people in one particular area suffered a very low rate of typhoid casualties during a 1948 epidemic.
Mathematical and computational approaches are making strides in understanding how life might have emerged and organized itself from the basic chemistry of early Earth
Life is a self-sustaining network of chemical reactions. A living system produces its own components from basic food sources in such a way that these components maintain and regulate the very chemical network that produced them. Based on this notion of life, several models of minimal living systems were developed during the 1970s. While these models captured an essential aspect of the organization of living things, however, they could not directly explain how such systems emerged from a primordial soup of basic chemicals.
Over the past several years, one of these early models—that of autocatalytic sets—has been explored in more detail, both mathematically and with computer simulations. Autocatalytic sets are self-sustaining networks of chemical reactions that create and are catalyzed by components of the system itself. Recent research has overturned early criticisms regarding the plausibility of the spontaneous origin of such networks, and scientists have even applied the theoretical concepts to real chemical and biological systems, yielding important insights regarding the possible emergence, structure, and evolution of such systems. While many studying the origin of life are still focused on finding a self-replicating RNA molecule that could have served as the basis for modern life (see “RNA World 2.0,” The Scientist, March 2014), some now consider autocatalytic sets necessary conditions for its start.
Updated classics and new techniques help microbiologists get up close and quantitative
Ever since Antonie van Leeuwenhoek espied the cavorting, swiftly swimming tiny critters he called animalcules through a small sphere of glass held in a metal frame, microscopes have figured into microbiological advances.
The stunning diversity of microbes, whether harvested from the human gut or scraped from the ocean floor, has increasingly led researchers to explore microbial behavior. As research entered the age of DNA, microscopes fell out of favor, and gaps in understanding the twitching, swimming, or creeping movements of microbes individually and as a colony have persisted.
Studying bacterial behavior requires techniques to view, track, and analyze these organisms in motion. Today, this involves new tools, such as genetically encoded fluorescent reporters, and improvements on old ones, such as quantitative methods for analyzing the complex swirls and spirals of bacterial colonies growing on agar plates. Even microscopes have made a comeback over the past two decades, thanks to the advent of small, relatively inexpensive cameras and increasingly sophisticated image-analysis programs, explains biologist Nicolas Biais of Brooklyn College.
The Scientist sought out some creative solutions for studying microbes on the move, en masse or one by one.
Concentrated extracts of maple syrup combined with antibiotics reduced the growth of four common bacterial strains
Maple syrup may help fight disease-causing bacteria, including antibiotic-resistant strains that often grow in health-care settings, says a study published online in Applied and Environmental Microbiology.
Concentrated extracts of maple syrup combined with antibiotics significantly reduced the growth of four common bacterial strains and bacterial communities called biofilms, the study found.
Bacterial biofilms accumulate on medical surfaces and devices, such as catheters and artificial joints, and are responsible for many antibiotic-resistant hospital infections, research has shown.