Mysterious ‘ship goo’ contains new life forms

It came from the deep: a viscous black gunk oozing from the rudder shaft of a ship. At the end of August 2024, the crew of the Great Lakes research vessel R/V Blue Heron, first spotted the substance when the boat was brought to a Cleveland shipyard for propeller repairs. From the outset, no one was sure what to make of it, according to Doug Ricketts, Marine Superintendent at the University of Minnesota Duluth, Large Lakes Observatory.

The muck looked like thick grease or oil, Ricketts tells Popular Science, but the rudder shaft wasn’t supposed to be lubricated by anything more than lake water. Instead of a strong petroleum odor, the goop had a metallic smell. It also didn’t leave a sheen on water, nor burn up in a blowtorch flame, during informal tests conducted by Blue Heron Captain Rual Lee. So, what was it?  

A cup half full of goo

On the quest for answers, Ricketts brought a paper coffee cup half-filled with the mystery goop (labeled “ship goo” in haphazard marker strokes) to university scientists. Laboratory analysis has prompted more questions than clarity, but the initial assessment of the “ship goo” yielded at least one startling discovery. The mysterious tar-like material contained previously unidentified forms of life. 

“I really didn’t think we’d get anything, to be honest,” Cody Sheik, a microbial ecologist at the University of Minnesota Duluth tells Popular Science. “Usually, when you’re given a cup of tar,” you don’t expect much, he adds. Under that assumption, he “handed it off to a graduate student and said ‘good luck’.” 

The graduate student successfully extracted DNA from the goo, defying Sheik’s initial expectations– but still, he thought it might be routine sample contamination. It was only after the lab sent the extracted DNA off for preliminary, single-gene sequencing that Sheik realized he was in uncharted territory. When the results came back, he was shocked. “A lot of the sequences came out really novel. I was like, ‘oh, oh no, okay– this is a whole different story’,” he says. 

[ Related: Pollution-eating microbes are thriving in infamous NYC canal. ]

ShipGoo01 and friends

For a deeper look into the goo’s microbial makeup, Sheik and his colleagues sent the sample for a second round of sequencing. This time, they examined the whole genomes inside of the goo, instead of just a single key gene region. The analysis confirmed that, though the goop microbes weren’t especially diverse, they were unique. They reconstructed the genomes of more than 20 microbes, and compared them to comprehensive databases of previously identified organisms. According to Sheik, they found several novel archaea– members of a domain of single-celled, prokaryotic life that are distinguished from bacteria by their cell membrane composition. 

One of the microbes they found represents, not just a new species, but an entirely new order of archaea. For now, the scientists are officially referring to it as ShipGoo01. Another promising, oddball microbe could be a whole new bacterial phylum, Sheik says. If confirmed, that would probably be christened ShipGoo002. Others, too, might prove new to science. “There’s several of them that may be new genus, may be new families, for sure,” he notes.

ShipGoo01 seems to be anaerobic, meaning it prefers an oxygen-free environment. Other microbes in the goo seem to gobble oxygen up and Sheik suggests that it’s possible these exist in a mutually beneficial balance.

Building a 1,000 piece puzzle without a picture

Of the more familiar microbes and genetic markers, database comparison indicates that the bulk of the teeny tiny organisms are similar to those associated with oil wells, tar pits, and other hydrocarbon systems. Several seem to be related to microorganisms with international origins– from places like Germany. “That’s been kind of fun– trying to figure out where [it’s from] and why it’s in the rudder system here. It’s becoming quite baffling,” Sheik says. In part, again, because the Blue Heron’s rudder isn’t regularly greased with oil, and because it sails on the Great Lakes in the Midwest. 

The ship hasn’t always been in University of Minnesota custody. It was purchased pre-owned in 1997, Ricketts says, so it’s entirely possible that the prior owners of the vessel did apply some sort of petroleum-based lubricant to the rudder shaft. But generally microbes need a steady food supply. Without any additional influx of grease in over 25 years, it’s hard to know what the oil-associated microbes might be eating after all this time. 

Perhaps they’re subsisting off of the metal itself, though Ricketts notes that the rudder shaft didn’t look particularly damaged. Maybe organic matter from the lake water feeds the micro-beasts. Or maybe some secret third thing is going on. 

“The more we start getting into this, the more I’m kind of clueless here,” Sheik says. “We’re doing a lot of sleuthing to try to figure this thing out.” 

He’s hoping to get better answers on what the microbes are floating around in, and all of the microbial metabolic pathways present in the goop. Sheik also imagines using chemical isotope analysis down the line to establish where the atoms in the system are coming from. The carbon and nitrogen in algae, for instance, have a very different profile from the equivalent molecules in motor lube. “It’s like a 1,000 piece puzzle that we’re trying to put together,” without any picture on the box to go off of, Sheik says. Once more of the image becomes clear, his lab plans to publish their findings in a peer-reviewed scientific journal. 

[Related: Can microbes that devour plastic waste be transformed into food for humans?]

Goo be gone?

But there’s one big challenge the scientists might not be able to overcome. The cup of goo (comprising about 100 milliliters of gunk) was the only sample taken, and getting more could be difficult–nigh impossible. The ship would have to be put in dry dock, with the rudder, once again, disassembled. And “unfortunately, they did a really good job cleaning it last time before they put it back,” Sheik says. The rest of the ship goo “may be lost forever.”   

Or maybe not. “I don’t think this ship is unique. I really strongly suspect that if you took the rudder post of any ship anywhere, there’s a possibility of finding some organism–maybe a new organism–in that space,” Ricketts says. 

Before this, it would’ve been easy for him to imagine strange microorganisms popping up in a ship galley or on a fuel filter. But of all the places for something like this to be found, the mechanical rudder shaft at the far end of a ship is among the weirdest, Ricketts says. It just goes to prove, “microbes are everywhere.” 

To better understand more of those undiscovered lifeforms, hiding in plain sight, Sheik says his lab would need secure funding and resources. Like many university science labs that rely, in large part, on taxpayer dollars, the future of his work is up in the air. 

“Right now we’re in this weird spot where we’re just trying to struggle to keep our labs open,” he says. He worries that, moving forward, we’ll miss out on ShipGoo3– but also on all the would-be advances that might come from it. 

Many prior microbe discoveries have proved useful in fields as varied as waste management and pollution remediation to life-saving drug development. “As these dollars go away, our ability to do this primary research that can drive innovation goes away and could be lost for a very long time.”

 

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