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Credit: Francis Choi

Submerged 60,000-year-old fossilized forest could be hiding medicines of the future

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Apr 14, 2020, 3:03 AM EDT (Updated)

Not every fossil is a dinosaur skeleton waiting to be unearthed in layers of rock and dust.

Drowned in the depths of the sea, a prehistoric cypress forest that had been lost to time has been rediscovered off the coast of Alabama some 60,000 years later. Eerie images captured through the murk are not even the most fascinating thing about the phantom trees. NOAA has funded a research team from Northeastern University and the University of Utah to go back in time and not only find out what this ancient ecosystem was once like, but potentially bring new medicine and biotechnology to the surface.

How could a forest that perished millennia ago, fell to the ocean floor, and became fossilized in peat and sediment possibly give us biofuels and medications we can hardly imagine? Shipworms.

Creepy name aside, a shipworm is actually a type of clam that gorges on sunken wood, earning itself the nickname “termite of the sea.” These creatures are bivalve mollusks whose appetite for dead trees made them evolve differently from their filter-feeding cousins. Their need to bore into the wood they eat ended up influencing their evolution, turning a hinged shell into a tubular one that appears more wormlike. Because the tough fibers of wood are notoriously hard to digest, symbiotic microbes (symbionts), whose digestive systems can handle it, live in special cells found in shipworms’ gills, helping them convert wood into animal tissue.

“We are particularly interested in a group of bacteria that are symbionts with an ancient history of living inside the cells of shipworms. We named the genus Teredinibacter and were the first to describe them,” Dan Distel, director of the Ocean Genome Legacy Center at Northeastern University, tells SYFY WIRE. “We first got interested in them because they are among the best producers of enzymes that can break down plant cell wall materials, making them a good choice for discovery of enzymes useful for biofuel production.”

What is truly amazing about these bacteria is that, in addition to boosting biofuels, they also contain compounds that have tremendous biopharmaceutical potential. Not only that, but because the microbes themselves have already been accepted by an animal, they are less likely to be toxic to humans. Think of it as a sort of pre-screening. There is already one compound from a shipworm microbe that could possibly be used as an antiparasitic. If you know anything about parasites, you need some powerful meds (often with horrible side effects) to get rid of those body-snatchers.

 “We were actually pretty surprised to discover a few years ago that their genomes are a good source of drug lead candidates too,” Distel says of the bacteria. “So far my colleagues at the University of Utah, Eric Schmidt and Margo Haygood, have discovered and described two new compounds from these bacteria that have antibiotic or antimicrobial activity, and one of these is now being investigated as a potent antiparasitic compound.”

The same enzymes made by the shipworm bacteria to break down wood have coincidentally ended up opening new frontiers for medicine. These enzymes somehow make their way down from the gill, where these microbes live, to the part of the shipworm's digestive tract that excusively breaks down wood. The team hypothesizes that the shipworm's guts have evolved that way since the part that digests wood, which would normally be swarming with microbes, is nearly sterile. It could be that the microbes living in the gill contribute to that by producing antimicrobials. This is being studied further.

Parasites aren’t the only enemy of bacteria from these shipworms. There may be more advantages that have come from living in an environment that remained undisturbed for tens of thousands of years.

"We include the shipworm symbionts in assays for all sorts of other activities, such as neurological, anticancer, anti-HIV, etc," Haygood tells SYFY WIRE. "Shipworm symbionts have the potential to make many complex chemicals that have never been seen before and may have useful activities. The numerous drugs that come from microbes didn't evolve to solve human medical problems, it's more a lucky coincidence."

During a time when many labs have been shut down, Schmidt and Haygood recently received permission to research chemical compounds from the fossilized forest’s bacteria to aid in the fight against COVID-19. It’s as if a forest that died in the distant past somehow had foresight for a dystopian future.

"Typically, it takes months to years to validate an assay, and the fastest advancement to drugs takes several years. Here we are pivoting quickly and hope to accelerate this process, but we are just at the beginning steps," Schmidt tells SYFY WIRE.

Whether these bacteria can take down the virus is still under investigation, so for now we can only hold our breath in quarantine.

(via NOAA)


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