As a result of an oil spill, it is usually the smallest organism that does most of the cleaning. Surprisingly, scientists don’t know much about the tools that these small cleaning teams have.
But now, thanks to a new study, researchers have discovered an entirely new cycle of natural hydrocarbon emissions and recycling enabled by a diverse range of tiny organisms – could help us better understand how some microbes have the power to clean the oil. shedding leaves in the ocean.
“Just two species of marine cyanobacteria add up to 500 times more hydrocarbons to the ocean each year than all other types of petroleum inputs into the ocean, including natural oil spills, oil spills, fuel dumping and runoff from land, ”said earth scientist Connor Love of the University of California, Santa Barbara (UCSB).
But unlike more familiar human donations of hydrocarbons into our ocean, this is not a one – way local waste.
These hydrocarbons, mainly in the form of pentadecane (nC15), are distributed over 40 percent of the Earth’s surface, and are fed by other microbes. They are always cycled in such a way that Love and colleagues estimate that only about 2 million metric tons are present at the water at any one time.
“Every two days you make and eat all the pentadecane in the ocean,” Love explained.
(Luke Thompson, Chisholm Lab / Nikki Watson, MIT)
Above: A globally distributed species of marine cyanobacteria, Prochlorococcus.
Today, the traces of human hydrocarbon can be found in most of what is around us. We emit these molecules made up of just carbon and hydrogen atoms in many ways – mainly through the extraction and use of fossil fuels, but also from plastic. , cooking, candles, painting, and the list goes on.
So perhaps it should come as no great surprise that signals from our own emissions have eroded our ability to see the vast hydrocarbon ring that naturally appears in our oceans.
He made an effort to Love and colleagues clearly identify this global circle for the first time.
Far from most sources of human hydrocarbons, in nutrient-poor subtropical Atlantic waters, the team had to position the vessel they were sampling to address its wind, so the diesel fuel containing pentadecane did not contaminate the seven survey sites. No one was allowed to cook, smoke or paint on deck during gatherings.
“I don’t know if you’ve ever been on a boat for a long time, but you paint every day,” explained Earth scientist David Valentine from UCSB. “It’s like the Golden Gate Bridge: You start at one end and before you reach the other end it’s time to start over.”
Back on land, the researchers were able to confirm the presence of the pentadecane in their seawater samples of biological origin, using gas chromatography.
Analyzing their data, they found concentrations of pentadecane increased by increased abundance of cyanobacteria cells, and the geographical and vertical circulation of the hydrocarbon was in line with the ecology of these microphones.
Cyanobacteria Prochlorococcus and Synechococcus they are responsible for about a quarter of the global ocean energy conversion of organic matter (primary production) and previous laboratory cultivation has shown that they produce pentadecane in the process.
Valentine describes the cyanobacteria that tend to use pentadecane as a more potent component for cellular organs, such as those found in chloroplasts (the organelle that takes photosynthesis).
A pentadecane cycle in the ocean also follows the diel cycling of these cyanobacteria – the direct migration into the water in response to changes in daylight intensity.
Taken together, these findings suggest that cyanobacteria are in fact the source of the biological pentadecane, which is then ingested by other microorganisms that produce the carbon dioxide that the cyanobacteria then use to continue the cycle.
Earth’s natural hydrocarbon cycle. (David Valentine / UCSB)
Love’s team identified dozens of surface-dwelling bacteria and archaea that bloomed in response to the addition of pentadecane in their samples.
So they then tested to see if the hydrocarbon-eating microbes could break down on petrol. The researchers added petroleum hydrocarbons to samples growing closer to areas with active oil, in the Gulf of Mexico.
Unfortunately, only the marine samples from areas exposed to non-biological hydrocarbons contained growing microbes in response to these molecules were consumed.
DNA tests showed that genes thought to encode proteins that could reduce these hydrocarbons were differentiated between the microbes, with an obvious difference between those consuming any hydrocarbons and those who eliminated those with petroleum production.
“We have shown that a large and fast hydrocarbon cycle occurs in the ocean, and that it differs from the ocean’s ability to respond to petroleum input,” Valentine said.
The researchers have begun sequencing the genomes of microbes in their sample to further understand the ecology and physiology of the creatures involved in the Earth’s natural hydrocarbon cycle.
“I guess [these findings reveal] just to the extent that we do not know about the ecology of many hydrocarbon organisms, “Love said.
This research was published in Nature microbiology.