Big Ideas: Germ Warfare
Lechuguilla cave runs beneath new Mexico's Carlsbad Caverns National Park like a hidden vein. It reaches depths of more than 1,600 feet and stretches on for more than 140 miles. Water rising through an aquifer originally carved out the meandering tunnels and soaring chambers, and until 1986, the sprawling space remained submerged in darkness.
The fifth-longest cave in the world went undiscovered until a group of Colorado cavers requested government permission to dig there, believing there was more to the then-400-foot, dead-end passage. Skeletons of bats found inside the cave show that the previous opening to the outside disappeared around 50,000 years ago. But life was there millions of years earlier — consuming, evolving and surviving.
Hazel Barton, an associate professor of biology, geology and environmental science at the University of Akron, helped map the 4 million-year-old cave system that lies beneath the Chihuahuan Desert. Barton, who was featured in the 2001 Imax film Journey Into Amazing Caves, returns to Lechuguilla Cave a few times a year. A permit is needed to enter, and she was among just 36 people the National Park Service granted the privilege to in 2012.
But it was bacteria she collected from deep within an isolated portion of the cave during a 2007 trip that has the biggest implications for those of us living on the surface. She catalogued 93 antibiotic-resistant bacteria strains. All were resistant to at least one antibiotic that doctors currently use. Some were resistant to as many as 14. As a whole, they showed resistance to every pharmaceutical antibiotic now in use.
The bacteria inside Lechuguilla Cave aren't harmful to humans, but they show that antibiotic resistance is hard-wired rather than something that develops from overuse of pharmaceuticals in treating infectious disease. Barton says such traits in bacteria that have never been exposed to anything manmade can help scientists better understand resistance and develop new medicines.
Barton was originally collecting bacteria samples from Lechuguilla Cave because she found that the diversity of microbial organisms there was much greater than she initially expected in such a bleak and barren environment. She was curious about why they were there, and how they grew.
"It's so limited in energy, the bacteria will start attacking each other," Barton says. "They are actually the top predators in their own ecosystem."
Looking at that moment of interaction interests Barton. When bacteria fight, they create and release antibiotic weapons to kill their rivals. When that struggle for survival and eons of evolution collide, those chemicals are more varied and sophisticated than what can be created in a lab, opening the door for the discovery of new antibiotics.
"They have a lot of very clever pathways that let them cheat and do synthesis that we could never do," Barton says. "And they've been testing this for, potentially, billions of years. They've come up with this arsenal that works. It's up to us to find these organisms that kill other organisms and steal that arsenal. It's what virtually every [antibiotic] on the market is."
Barton discovered the antibiotic resistance of bacteria she collected from Lechuguilla Cave through her work with Gerry Wright from McMaster University in Ontario, Canada. The pair also work with Brian Bachmann of Vanderbilt University in Nashville, who focuses on the development of new antibiotics. "We're kind of like this triangle," she says. "I do the [bacteria] culture work and these guys do the production and look for resistance."
Barton is involved with several different projects related to her library of organisms from Lechuguilla Cave. One looks at how the microbials there take in nitrogen gas. Another looks at how they signal and communicate with each other. Yet another is the development of a new antibiotic from bacteria collected from inside Lechuguilla Cave. She says that may just be the start, too.
"There are a lot of antibiotics out there waiting to be discovered," Barton says. "With the work that Brian and I have done, we've already found one organism from that library that made 36 antimicrobial agents, so the potential is huge."
in the cle
12:00 AM EST
March 23, 2013