Tag Archives: bacteria

Amazing Designs of Life

The More We Know About Genes, the Less We Understand by Carl Zimmer

All living things, ourselves included, turn genes on and off in a similar way, by making switch-like proteins called transcription factors. And as scientists have identified more of these, they’ve discovered something remarkable: They form a chain of command. The job of some transcription factors is to switch others on and off, and they in turn are controlled by other transcription factors. Even a seemingly simple microbe like E. coli has an impressive hierarchy. Just nine genes rule over about half of the 4,000-odd genes in E. coli.

E. coli’s network allows it to respond quickly to the challenges it meets, from starvation to heat to the loss of oxygen. It can rapidly reorganize itself, switching on hundreds of genes and switching off hundreds of others. What makes this network all the more impressive are the feedback loops that keep it from spinning out of control. When one gene switches on, for example, it may make a protein that shuts down the gene that switched it on in the first place.

Yet even as scientists uncover this network, they discover yet another mystery. In the latest issue of Nature, scientists reported an experiment in which they wreaked havoc with E. coli’s network. They randomly added new links between the transcription factors at the top of the microbe’s hierarchy. Now a transcription factor could turn on another one that it never had before. The scientists randomly rewired the network in 598 different ways and then stepped back to see what happened to the bacteria.

You might expect that they all died. After all, if you were to pop open the back of an iPod and start linking its components together in random ways, you’d expect it to crash. But that’s not what happened.

About 95 percent of the rewired bacteria did just fine with their new networks. They went on with their lives, feeding, growing and dividing. Some even performed better than microbes with the original wiring, under some conditions.

Clay Versus MRSA Superbug

“Healing clays” hold promise in fight against MRSA superbug infections and disease

Scientists from Arizona State University report that minerals from clay promise could provide inexpensive, highly-effective antimicrobials to fight methicillin-resistant Staphylococcus aureus (MRSA) infections that are moving out of health care settings and into the community.
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Unlike conventional antibiotics routinely administered by injection or pills, the so-called “healing clays” could be applied as rub-on creams or ointments to keep MRSA infections from spreading
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In their latest study, funded by the National Institutes of Health, Williams, Haydel and their colleagues collected more than 20 different clay samples from around the world to investigate their antibacterial activities… The researchers identified at least two clays from the United States that kill or significantly reduce the growth of these bacteria

Also listen to a podcast with the researchers, Lynda Williams and Shelly Haydel, that provides much more detail. The Science Studio podcasts from Arizona State University provides great science podcasts.

Bacteria Survive On All Antibiotic Diet

Bacteria Survive on All-Antibiotic Diet

The scientists wanted to make sure they had a good control—a group of bacteria that didn’t grow at all—so they bathed some of the bacteria in antibiotics. But there was a problem: The bacteria didn’t just survive in the antibiotics, they consumed them. The researchers then gathered soil from 11 sites with varying degrees of exposure to human-made antibiotics (from manure-filled cornfields to an immaculate forest) and found that every site contained bacteria, including relatives of Shigella and the notorious E. coli that could survive solely on antibiotics. And these weren’t just piddling doses—the bacteria could tolerate levels of antibiotics that were up to 100 times higher than would be given to a patient, and 50 times higher than what would qualify a bacterium as resistant.

Radiation Tolerant Bacteria

metallireducens bacteria

This image is from the Eye of Science web site (which has many great images):

Bacteria: Uranium waste bacteria (metallireducens bacteria) [the green in the image] Electron microscopy… This bacteria is able to survive in radioactive environments and turn the uranium waste from a soluble form (that can contaminate water supplies) to a solid form.

Other species of Geobacter bacteria can eliminate petroleum contamination in polluted water and convert waste organic matter to electricity. Geobacter sp. are anaerobic bacteria (living without oxygen) that use metals to gain energy in the same way that humans use oxygen. Coloured scanning electron micrograph, Magnification: x3,600 and x4,800

Secret Life of Microbes

New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems

Nowhere is the principle of “strength in numbers” more apparent than in the collective power of microbes: despite their simplicity, these one-cell organisms–which number about 5 million trillion trillion strong (no, that is not a typo) on Earth–affect virtually every ecological process, from the decay of organic material to the production of oxygen.

But even though microbes essentially rule the Earth, scientists have never before been able to conduct comprehensive studies of microbes and their interactions with one another in their natural habitats.
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Because microbes are an ecosystem’s first-responders, by monitoring changes in an ecosystem’s microbial capabilities, scientists can detect ecological responses to stresses earlier than would otherwise be possible–even before such responses might be visibly apparent in plants or animals, Rohwer said.

Evidence that viruses–which are known to be ten times more abundant than even microbes–serve as gene banks for ecosystems. This evidence includes observations that viruses in the nine ecosystems carried large loads of DNA without using such DNA themselves. Rohwer believes that the viruses probably transfer such excess DNA to bacteria during infections, and thereby pass on “new genetic tricks” to their microbial hosts. The study also indicates that by transporting the DNA to new locations, viruses may serve as important agents in the evolution of microbes.

Vaccine For Strep Infections

Engineered Protein Shows Potential as a Strep Vaccine

A University of California, San Diego-led research team has demonstrated that immunization with a stabilized version of a protein found on Streptococcus bacteria can provide protection against Strep infections, which afflict more than 600 million people each year and kill 400,000.
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Group A Streptococcus (GAS). GAS causes a wide variety of human diseases including strep throat, rheumatic fever, and the life-threatening “flesh-eating” syndrome called necrotizing fasciitis. Studies were performed using M1 protein, which represents the version of M protein present on the most common disease-associated GAS strains.
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“We created a modified version of M1 with a more stable structure, and found that it is just as effective at eliciting an immune reaction, but safer than the original version of M1, which has serious drawbacks to its use in a vaccine.”

Clouds Alive With Bacteria

Clouds above the Mesa Trail by John Hunter

Earth’s Clouds Alive With Bacteria

Clouds are alive with tiny bacteria that grab up water vapor in the atmosphere to make cloud droplets, especially at warmer temperatures, a new study shows.

The water droplets and ice crystals that make up clouds don’t usually form spontaneously in the atmosphere – they need a solid or liquid surface to collect on. Tiny particles of dust, soot and airplane exhaust – and even bacteria – are known to provide these surfaces, becoming what atmospheric scientists call cloud condensation nuclei (CCN).
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These microbes could be carried into the atmosphere from an infected plant by winds, strong updrafts or the dust clouds that follow tractors harvesting a field. Christner and others suspect that becoming cloud nuclei is a strategy for the pathogen to get from plant to plant, since it can be carried for long distances in the atmosphere and come down with a cloud’s rain.

The next step in determining how big a role biological particles play in cloud droplet formation is to directly sample the clouds themselves, Christner says.

Bacteria Can Transfer Genes to Other Bacteria

From page 115 of Good Gems, Bad Germs:

Microbiologists of the 1950’s did not appreciate the stunning extent to which bacteria swap genes… In 1959 Japanese hospitals experience outbreaks of multidrug-resistant bacterial dysentery. The shigella bacteria, which caused the outbreaks, were shrugging off four different classes of previously effective antibiotics: sulfonamides, streptomycins, chloramphenicols, and tetracyclines… In fact, the Japanese researches found it quite easy to transfer multidrug resistance from E. coli to shingella and back again simply by mixing resistant and susceptible strains together in a test tube.

One Reason Bacteria Gain Tolerance So Quickly

I recently read Good Gems, Bad Germs as part of my effort to learn more about bacteria, viruses, how are bodies work, cells, microbiology etc.. It is a great book, I highly recommend it. Page 111:

In 1951 the husband-wife team of Joshua and Esther Lederberg, microbiologists at the University of Wisconsin, demonstrated that their elegantly simple proof that preexisting mutations, not gradual tolerance, accounted for the many instances of new drug resistance… This meant that every new antibiotic became a powerful new force for bacterial evolution, winnowing away every bacterium but the otherwise unremarkable one that could survive its effects. With its competition gone, that lucky mutant could populate, giving rise to a newly resistant colony overnight.

Since bacteria can grow remarkably quickly, eliminating all but a small number just means that the new population boom will come from those few, resistant, ancestors. But that is not the only reason bacteria are so challenging to fight. They have been around billions or years and have survived because they can adapt well. Bacteria, in fact, can get their genes from distantly related bacteria. So if one bacteria gains immunity another bacteria can get that immunity by getting genes from that other bacteria (seems like science fiction but it is actually science fact).

People Have More Bacterial Cells than Human Cells

Humans Carry More Bacterial Cells than Human Ones

All the bacteria living inside you would fill a half-gallon jug; there are 10 times more bacterial cells in your body than human cells
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The infestation begins at birth: Babies ingest mouthfuls of bacteria during birthing and pick up plenty more from their mother’s skin and milk—during breast-feeding, the mammary glands become colonized with bacteria. “Our interaction with our mother is the biggest burst of microbes that we get,”
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there are estimated to be more than 500 species living at any one time in an adult intestine, the majority belong to two phyla, the Firmicutes (which include Streptococcus, Clostridium and Staphylococcus), and the Bacteroidetes (which include Flavobacterium).
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probiotics – dietary supplements containing potentially beneficial microbes – have been shown to boost immunity. Not only do gut bacteria “help protect against other disease-causing bacteria that might come from your food and water,” Huffnagle says, “they truly represent another arm of the immune system.”
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But the bacterial body has made another contribution to our humanity – genes. Soon after the Human Genome Project published its preliminary results in 2001, a group of scientists announced that a handful of human genes – the consensus today is around 40 – appear to be bacterial in origin.

How cool is science? Very, I think 🙂