Archive for the ‘microbiology’ Category

What’s eating this 400-year-old painting? A whole ecosystem of microbes

December 11th, 2018
The middle image shows the painting as it now appears, with close-ups of four centuries of damage and wear on the right. The asterisks mark the locations of Caselli and her colleagues' samples.

Enlarge / The middle image shows the painting as it now appears, with close-ups of four centuries of damage and wear on the right. The asterisks mark the locations of Caselli and her colleagues' samples. (credit: CC BY license, with permission from )

A new study describes the complex ecosystems of bacteria and fungi that live and feast on a 17th-century painting—and how other species of bacteria may one day help art conservators fight back.

If you could zoom in for a microscopic look at an oil painting on canvas, you would see many thin, overlapping layers of pigments—powdered bits of insects, plants, or minerals—held together with oils or glue made from animal collagens. Many of those pigments and binding materials are surprisingly edible to bacteria and fungi. Each patch of color and each layer of paint and varnish in an oil painting offers a different microbial habitat. So when you look at a painting, you’re not just looking at a work of art; you’re looking at a whole ecosystem.

Microbes’ artistic taste

To better understand these microscopic art vandals, University of Ferrara microbiologist Elisabetta Caselli and her colleagues turned to a Renaissance painting called “Incoronazione della Virgine,” by painter Carlo Bononi. The painting once adorned the ceiling of the Basilica of Santa Maria in Vado, Italy. When an earthquake damaged the church in 2012, staff took down the 2.8 meter (9.18 foot) round canvas from where it had hung since 1620 and leaned it against the wall in an inner niche of the church.

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Posted in art history, microbiology, microbiota, museums, preservation, Renaissance, science | Comments (0)

Bacteria engage in chemical warfare against viruses

December 5th, 2018
Bacteria engage in chemical warfare against viruses

Enlarge (credit: Getty / Aurich)

Bacteria have plenty of ways to combat the viruses that plague them, called phages. The CRISPR-Cas system and restriction enzymes that cleave phage DNA are the best understood, but there are others. They use a variety of different mechanisms and stop phages at various stages of infection, but they all rely on biological actors: proteins and RNA. New work has just revealed, though, that bacteria can use chemical weapons as well.

Bacteria produce a wide range of active small molecules that are not essential for survival but do confer a growth advantage. Some of these small molecules, which kill their fellow microbes, are already used (by us) as antibiotics. It was also observed, more than fifty years ago, that bacteria make molecules that can inhibit the growth of phages. But it wasn't clear whether these molecules are made specifically because they slow down the phages. Only now, with the background knowledge that (a) bacteria make a lot of bioactive compounds, many of which do combat other microorganisms, and that (b) phages are a major scourge for bacteria, did researchers think to check.

Biochemists screened 4,960 compounds for their ability to protect E. coli from phage infection and found 11 that could. Nine out of the 11 were what are termed DNA-intercalating agents. The nucleotides that comprise DNA (A,T, C, and G) are flat molecules, and they're stacked parallel to each other along the DNA helix. DNA-intercalating agents slide in between them, interfering with the copying of DNA during cell division.

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Medieval European plague genomes hint at of Black Death’s travels

December 5th, 2018
Scanning electron micrograph depicting a mass of <em>Yersinia pestis</em> bacteria (the cause of bubonic plague) in the foregut of the flea vector.

Enlarge / Scanning electron micrograph depicting a mass of Yersinia pestis bacteria (the cause of bubonic plague) in the foregut of the flea vector. (credit: Rocky Mountain Laboratories / Wikimedia)

Barbara Bramanti grew up near Florence, Italy, worked for a while in Mainz, Germany, and is now at the University of Oslo in Norway. Her career has taken her across a decent swath of Western Europe—but not nearly across as big of an area as that ravaged by the plague she studies.

In her latest work, she and her colleagues associate Europe's Black Death plague outbreak with a change in trade policy in Asia.

Where’d they come from?

Yersinia pestis, the subject of her research, is the bacterium responsible for three bubonic plague pandemics over human history. The first was the Justinian Plague, which started in Constantinople around the year 541 CE and devastated the Byzantine Empire until the middle of the eighth century. The second began with the Black Death, which killed at least 30 percent of the population of Western Europe between 1346 and 1353 and then continued rampaging over the next 400-ish years. The third started in 1772 in Yunnan province, in southwest China, and is still currently underway.

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Posted in Biology, disease, evolution, microbiology, science, the plague | Comments (0)

Kitchen sponges are festering germ dens—and sanitizing them doesn’t help

July 31st, 2017

Enlarge / Some germy places in the house include the kitchen faucet and sponges. Typically people wash their hands after handling raw meat in the kitchen and frequently use sponges or cloths to wipe germs from surfaces in the kitchen. (Photo by Zbigniew Bzdak/Chicago Tribune/MCT via Getty Images) (credit: Getty | MCT)

Scientists have long thrown shade at the unassuming kitchen sponge. The household staple skulks in sinks amid dirty dishes and soggy food scraps, sopping up and amplifying microbial forces capable of invading clean food spaces. The savvy kitchen-goer may think they have this situation locked down—a simple toss through a sanitizing dishwasher cycle or a sizzling swirl in the microwave… and done. Sudsy germsplosion averted.

Nice try, says science.

In a comprehensive study of 14 household sponges and their microbial inhabitants published in Scientific Reports, researchers confirmed that kitchen sponges are indeed domestic abominations. Moreover, any sterilizing attempts only seem to temporarily free up sponge-space for potential pathogens, which rapidly recolonize the festering scrubber.

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Posted in food safety, infectious diseases, microbes, microbiology, science, sponge | Comments (0)