bacteria – Page 4

02.07.2013

bacteria colonizing the antarctic

This drill recovered intact water samples from Lake Whillans

The New York Times has an interesting write up on the discovery of bacteria species in one of the frozen lakes of Antarctica. The bacteria were found about four feet deep in the sediment of Lake Whillans. They survive apparently requiring little oxygen or exposure to sunlight. Bacterial species have been previously discovered but the possibility of contamination couldn’t be ruled out during the previous expeditions. Here’s an excerpt on the discovery from the article:

After drilling through a half-mile of ice into the 23-square-mile, 5-foot-deep Lake Whillans, the expedition scientists recovered water and sediment samples that showed clear signs of life, Dr. Priscu said, speaking from McMurdo Station in Antarctica on Tuesday. They saw cells under a microscope, and chemical tests showed that the cells were alive and metabolizing energy.

Dr. Priscu said that every precaution had been taken to prevent contamination of the lake with bacteria from the surface or the overlying ice. In addition, he said, the concentrations of life were higher in the lake than in the borehole, and there were signs of life in the lake bottom’s sediment, which would be sealed off from contamination.

Much more study, including DNA analysis, is needed to determine what kinds of bacteria have been found and how they live, Dr. Priscu said. There is no sunlight, so the bacteria must depend on organic material that has drifted into the lake from other sources — for instance, decaying microbes from melting glaciers — or on minerals in the rock of the Antarctic continent.

More here.

01.30.2013

electric bacteria

Bacteria on the surface of an electrode

Scientists have taught bacteria to feed on electricity. Because the bacteria feed on iron, they were well suited for this kind of study. From Popular Science:

Researchers at the University of Minnesota, St. Paul, have coaxed a species of bacteria into trading their usual diet of partially-oxidized iron for a small current of electricity–a trick that may eventually make the microorganisms useful producers of biofuels.

The bacterium involved in the study was Mariprofundus ferrooxydans, a species that makes its home around hydrothermal vents on the seafloor. Like other iron-oxidizing bacteria, M. ferrooxydans relies on a form of soluble iron, called ferrous iron, or Fe(II), as a source of the electrons it needs to breathe. When plenty of oxygen is present, ferrous iron readily gives up its extra electron to the oxygen, to become the more stable Fe(III), or ferric iron–the kind of iron oxide we know of as rust. But in lower-oxygen environments, M. ferrooxydans’ can do oxygen’s job for it, thereby gaining energy from the extra electron.

In their experiment, the researchers deposited some M. ferrooxydans onto the surface of an electrode, which was tuned to release electrons at the same energy level that Fe(II) would provide. To get the organisms started in their new habitat, the scientists also added some of the bacterium’s natural food–Fe(II)–to the mix.

After letting the microbes multiply over the surface of the electrode for four weeks, they scraped some away and started a new colony on an electrode with no Fe(II) around. Amazingly, the bacteria continued to thrive, even after some were transplanted onward to a third electrode. Some nutrients were still provided to this colony, the study noted, but in amounts much too small to support the bacterium’s apparent growth.

01.17.2013

poo transplants

Clostridium difficile.

Count on Ed Yong to keep us updated on the wonderful world of gut bacteria. Today he brings news of clinical trials where fecal transplants are used to ward off infection by C. difficile. An excerpt is below. Click here for more.

Last week, I wrote about scientists who developed a stool substitute and used it to cure gut infections in two women. This sham poo contained 33 gut bacteria, which were meant to displace the harmful ones that were causing diarrhoea in the patients.

For decades, doctors have been doing the same thing using actual faeces. This unorthodox technique, known as a faecal transplant, has been used to treat over 500 people with recurring infections of the diarrhoea-causing bacteriumClostridium difficile.

The concept is inherently revolting, and many mistake it for pseudoscience. But faecal transplants work. Over 90 percent of patients make a full recovery, far greater than the proportion who responds to conventional antibiotics. (In fact, it may be antibiotics that cause recurring C.difficile infections in the first place, by annihilating the beneficial gut bacteria that normally keep such infections at bay.)

Some might argue that all of this amounts of anecdotal evidence. Faecal transplants have never been tested in a randomised clinical trial – the gold standard of medicine. But that objection no longer applies. The first results from a faecal transplant trial have been published in the New England Journal of Medicine, and they are a resounding vindication for the technique.

GOLLYGEE!

Tag: bacteria (page 4 of 5)

bacteria colonizing the antarctic

electric bacteria

poo transplants