Contrary to their name, extremophiles are not contestants on extreme entertainment shows like Fear Factor or really rad snowboarders. Extremophiles are bizarre microbes that lurk in places formerly considered too hostile to support life. Although extremophiles may live in all sorts of marginal environments, such as your office cubicle, they can thrive only in a very narrow range of specialized environmental conditions.
Most extremophiles aren't bacteria (simple cells without a nucleus), or the more complicated eukarya. Rather, they're members of a recently inaugurated group, archea (which sounds like a strange band name, but they didn't ask me). While archeans act like bacteria and lack a nucleus, they also share genes in common with eukarya and possess a number of genes unique to themselves.
Discovered in the 1960s at the hot springs of Yellowstone National Park by the research team of Thomas D. Brock, thermophiles like it hot. Regular bacteria get hot and bothered above 104 degrees Fahrenheit. Thermophiles prefer temperatures above 176 degrees, and some hyperthermophiles are happiest at 212 degrees F, the boiling point of water at sea level. You can find extremophiles adapted to a variety of really far-out environments, such as 10,000 leagues beneath the sea next to a thermal vent, or deep in the Earth's hot crust.
Other extremophiles include psychrophiles (cold lovers), acidophiles (which frolic in corrosive acid), alkaliphiles (found in the soda lakes of the Great African Rift), and halophiles (which are fond of extremely salty snacks).
Because extremophiles are suited to unusual environments, scientists (and corporations) are examining how they can be used for commercial or life-science research.
- The enzyme Tac polymerase, derived from thermophilic microbes such as T. acquaticus, is used in polymerase chain reaction technology (PCR) and DNA fingerprinting. Unlike standard enzymes, T. polymerase doesn't conk out during the heat cycle of copying DNA, so the PCR process could be automated, speeding up the Human Genome Project.
- One pint-size beastie puts Worldwide Wrestling Foundation luminaries such as Stone Cold Steve Austin, the Undertaker, and Tazz to shame. Deinococcus radiodurans, known informally as Conan the Bacterium, gobbles radiation like nobody's business. Isolated from a can of irradiated meat that had spoiled, D. radiodurans can suck up to 1.5 million rads of radiation, a dose 3,000 times higher than would kill most other living things.
- Some bugs like to eat oil, or toxic chemicals. Bioremediation applications are hoped for, but they are still in the early stages. Astrobiologists love studying these organisms because they are the closest analogy to putative life in the hostile conditions of other planets.
- Maybe they will do your homework. Weird organisms also may be pointing toward eventual biological computing applications. Laura Landweber, professor of molecular biology at Princeton, examines how directed test tube molecular evolution experiments can be used to develop DNA computing in peculiar cells with scrambled DNA, called ciliates. Mindful that these cells routinely perform complex computations as a chemical process, Landweber fused computers' binary coding of information with the cells' own DNA information to handle a complicated computing problem. The genes solved the puzzle as they unscrambled their tangled DNA.
No More Ring Around the Collar
I don't want you to think that this subject is unrelated to your everyday life. For the laundry detergent industry, eliminating Ring Around the Collar remains the Holy Grail, and they're really interested in this stuff (aside from the normal human fascination with the strange growths inside the coffee cups you left in the conference room over the weekend).
Collar soil, it turns out, contains lipids, proteins, and waxy build-up. Detergents are formulated primarily to attack oil and grease, so they have a hard time removing protein-based "ring around the color" stains such as blood stains, sweat, grass, and slime splotches.
Remember those detergent commercials where disembodied hands poured liquid on a spotless nappie? How exactly did they get the whites so white? They used major doses of bleach or enzymes. A century ago, clothes were washed in near-boiling water, but current cold-water detergents depend on enzymes derived from the type of common bacteria, like Bacillus subtilis or Bacillus licheniformis, that can be found loitering in trash heaps. About half of liquid detergents, a quarter of powder detergents, and almost all powdered bleach additives contain enzymes to get out stains that conventional surfactants won't touch.
Companies that make industrial enzymes are interested in extremophiles because the enzymes derived from them, called extremozymes, are stable, and they're exquisitely attuned to different temperatures, pH, salinity, and ionic strength. Because extremophiles already function in unusual natural conditions, they can be modified to work in the harsh conditions of industrial applications.
Employees of biotech companies like Genencor and Diversa, which make industrial enzymes, send their employees out to scour the far reaches of the globe to collect extremophiles. Dr. Brian Jones at Genencor International, The Netherlands, collects extremophiles from the Soda Lakes of the Great Rift Valley in East Africa. Conditions during your washing cycle, it turns out, have much in common with an alkaline soda lake fed by boiling hot springs.
Using recombinant DNA technology, Genencor developed an extremophile-derived detergent enzyme called Puradox that works in conjunction with other detergent additives and removes pills from cotton fabric. The enzyme was selected from a new species of obligatory alkaliphilic Bacillus (that's alkaline-loving BCE103, in case you're taking notes) representing a novel Bacillus RNA group. Dr. Jones also found a similar microbe that produced an enzyme that is being used to stonewash jeans for the fashion-conscious.
Despite the promised magic of the commercials, "Laundry detergents contain infinitesimal amounts of living material," says Tom Morrison, director of biomolecular discovery at BioTrove. Typically the proteases found in nature already are "pretty darn good enzymes," Morrison says, but laundry detergent companies, in a drive to reduce costs, rely on directed evolution to make them better.
To perfect these enzymes, biotech company Maxygen uses gene shuffling to mechanically recombine genes within the organisms, effectively swapping pieces of protein to get the desired functionality.
Directed evolution has nothing to do with the unmatched socks that keep proliferating in the dryer. Rather, scientists using a process of "controlled chaos" to get the perfect enzyme create a population of mutant enzyme "progeny" that each behave slightly differently from the parent molecule. Then they repeatedly screen the mutant progeny to find individual enzymes with the desired properties. (For more than you ever wanted to know about how enzymes work, check out this site.)
"We are seldom able to directly engineer unique characteristics," says Morrison. "Following mutagenesis [inducing mutations] you end up with thousands to billions of variants, each of which needs to be screened. In the process, 99.9% go down the drain. Arriving at the perfect enzyme is a major effort."
The Last Of The Great Explorers
As an extremophile buff, you can attend meetings with titles like "The Life of Brine: Halophiles in 2001" that cover archaea, bacteria, fungi, and algae adapted to living hypersaline environments. The organizers confess, "One of the perks of working with extremophiles is the opportunity to visit extreme environments." Perhaps joining the ranks of the fearless extremophile explorers in the far reaches of Antarctica or deep beneath the sea will provide you, too, with exotic adventure.
In the meantime, after the spin cycle is done, you might want to contemplate attending the next meeting: Halophiles 2004 will be held in Ljubljana, Slovenia.
Wendy Wolfson is living la vida loca near Boston. Share your extremophile experiences and laundry tips with her in her Listening Post discussion forum.