Will Cameron's deep-sea voyage yield breakthrough drugs?
Moviemaker's expedition to the Mariana Trench could usher in a new type of undersea lab that can extract chemical compounds from microorganisms living in the deepest parts of the ocean.
Blockbuster-moviemaker-turned-aquanaut James Cameron's solo dive in the Pacific to the Mariana Trench's Challenger Deep site last month opens up a vast, under-explored region of the world's oceans to researchers. There, scientists hope to discover, retrieve, and study a host of previously unknown organisms and chemical compounds that may someday help solve decades-old medical mysteries.
"What better place to look for adaptations and unusual compounds that have unusual characteristics than in the most extreme environments we can go to on this planet," says Richard Lutz, a professor of marine ecology and biology of deep-sea hydrothermal vents at Rutgers University and director of the school's Institute of Marine and Coastal Sciences.
In the April 12 issue of the journal Science, Lutz and co-author Paul Falkowski, a professor in Rutgers' departments of Geological Sciences and Marine and Coastal Sciences, point out that the handful of samples taken thus far from the ocean's depths have introduced scientists to new strains of an anaerobic bacteria known as actinomycetes, which Lutz calls "fascinating organisms with profound medical possibilities." Lutz and Falkowski cite one study where unique chemical compounds isolated from an actinomycete strain inhabiting deep-sea sediments about 3.3 kilometers down in the South China Sea have shown potent activities against three cancerous tumor cell lines and also showed antibacterial activities. Several different types of actinomycetes found in much-easier-to-reach terrestrial soils are already used to produce antibiotics such as streptomycin.
The success of Cameron's Deepsea Challenger submersible, which dove to 11 kilometers and spent about three hours there, means more biological samples can be collected from the deepest spots on the planet. Three other vessels have been to Challenger Deep, but two of those were robotic. The only other humans to see the Challenger Deep were U.S. Navy Lt. Don Walsh and Swiss oceanographer Jacques Piccard on board the bus-size bathyscaph Trieste in 1960. Japan's Kaiko robotic sub in March 1995 and the Nereus, an autonomous sub built by Woods Hole Oceanographic Institution engineers, made the trip in May 2009.
The Deepsea Challenger's ability to linger at the ocean bottom for an extended period of time means scientists on future dives might be able to study microbes such as actinomycetes in their natural environments. "We've never had the luxury of bringing back microbes that are what you call strict barophiles, microorganisms that can survive under great pressures," Lutz says. Typically, such organisms live at depths of greater than 5,000 meters. "If you take them to lower pressures, most likely they won't live due to the change in pressure, so you literally don't have a way of studying these organisms." With specially pressurized containers, a Deepsea Challenger aquanaut might even be able to bring living deep-sea microbes to the surface for study.
Lutz compares Walsh and Piccard's 1960 journey to the Challenger Deep to Sir Edmund Hillary's ascent of Mount Everest in 1953 and the 1969 Apollo 11 moon landing -- all manned, monumental accomplishments to extreme locations that could not easily be repeated at the time. Cameron's accomplishment re-ignites excitement for exploration in part because he is a hugely successful filmmaker, but also because he made the trip to the deepest part of the ocean himself in a well-designed vehicle expected to make many subsequent trips to Challenger Deep. Lutz is acquainted with the moviemaker, having worked as science director on the iMAX film "Volcanoes of the Deep Sea," which Cameron co-produced.
Other manned submersibles cannot dive deeper than about 7 kilometers, says Lutz, who has made more than 85 underwater voyages on board the mini sub Alvin and was part of the first deep-sea exploration of hydrothermal vents in 1979, when he was a postdoc at Yale University. Alvin, a Woods Hole submersible that has made 4,500 dives and served as the workhorse of the oceanographic community since the 1960s, is being rebuilt to travel to a maximum depth of about 6.5 kilometers. Meanwhile, China's manned submersible Jiaolong, which reached a depth of about 5 kilometers in 2011, is expected to make a 7-kilometer dive this year. Neither of these will be able to reach the 16 trenches throughout the world's oceans that extend deeper than 7 kilometers.
"When the hydrothermal vents were discovered, it sent shock waves throughout the scientific community and opened up a new area of research that has spanned the last three decades and spawned some of the best science that we've had in the ocean," Lutz says. With the Deepsea Challenger, "you now have access to a suite of organisms that you didn't previously."
Researchers at Scotland's University of Aberdeen Marine Biodiscovery Center (MBC) are studying the potential of deep-sea marine organisms as a source for new chemical compounds, which could be used to develop novel treatments for cancer, inflammation, infection and parasitic diseases. One organism they have studied is the bacterial species Dermacoccus abyssi sp. nov., found in a mud sample harvested via a robotic submarine from the Mariana Trench.
"We are currently working towards growing the Challenger Deep strains that we have under stress conditions -- including pressure -- to see if this affects their production of new chemicals," says Marcel Jaspars, Aberdeen's chair of organic chemistry.
The number of samples taken from depths below 6 kilometers is in the "low hundreds," Jaspars says. "At the moment more than half of species recovered from deeper than 3 kilometers are new to science. The trenches are mainly isolated ecosystems, so we expect there to be some very unusual endemic species of microorganisms there."
Less clear is whether the chemistry of these microorganisms is unique to deep-sea environments. Scientists do know that marine and terrestrial chemistries are "wildly different," he adds. "Seventy-five percent of marine chemical scaffolds are unique to the marine environment."
Cameron's journey to the Challenger Deep is a significant feat, but it is unlikely that technology as advanced as the Deepsea Challenger can be made widely available at this time, Jaspars acknowledges. Rather, he is hoping that the moviemaker's high-profile expedition will inspire a new generation of marine scientists and engineers to develop inexpensive sampling devices that can be used on any ship, something that Jaspars is working on with his Aberdeen colleagues. "This will be much more useful, as cost is the barrier to wider exploration," he says.