Carbohydrates and oil are almost synonymous in environmental science. After all, oil reserves make up almost all of the carbohydrates we encounter. But some hydrocarbons, which have their origins in biological sources, may play a greater environmental role than previously thought by scientists.
A team of researchers from the UC Santa Barbara and Woods Hole Oceanographic Institute (WHOI) surveyed this previously neglected area of oceanography for neglected global cycle signs. They also tested how its existence could affect the ocean’s response to oil spills.
“We have shown that there is a rapid, rapid cycle of hydrocarbons in the ocean, different from the ability of the ocean to respond to oil imports,” said Professor David Valentin, who holds the presidency of Norris in the Earth Department. Science at UCSB. The study, led by his fellow students Eleanor Arrington և Conor Love, appears in M Bacteriology of nature,
In 2015, an international team led by scientists at the University of Cambridge published a study showing that five-year-old hydrocarbons are produced by marine cyanobacteria in laboratory cultures. Researchers have suggested that this complication may be present in the ocean. The molecule seems to relieve stress in curved membranes, so it is found in things like chloroplasts, where tightly packed membranes require extreme curvature, Valentin explained. Some cyanobacteria still synthesize the compound, while other ocean bacteria readily consume it for energy.
Valentin is the author of a two-page commentary on the paper, with WHOI Senior Fellow Christopher Reddy deciding to continue the theme with Arrington և Love. They visited the Gulf of Mexico in 2015 and then in the Atlantic West in 2017 to collect samples and conduct experiments.
The team is sampling seawater from the nutrient-poor Atlantic Ocean known as the Sargasso Sea, known as the floating sargassum algae that flows into the Gulf of Mexico. “This is beautiful, clear, blue water with a Bermuda scent in the middle,” said Valentin.
Obtaining samples probably seemed like a daunting task. As the pentadecan is a common hydrocarbon of diesel fuel, the team had to take extra precautions to avoid contamination from the ship’s own plane. They forced the captain to turn the ship into a wind so that the emissions would not contaminate the samples; they analyzed the chemical signature of the diesel fuel to make sure that it was not the source of the five they found.
Moreover, no one could smoke, cook or paint on the deck while the researchers were collecting seawater. “It was a big deal,” said Valentin. “I don’t know if you’ve been on a ship for a long time, but you paint every day.” It is like the “Golden Gate” bridge. You start from one end, and as soon as you reach the other end, it’s time to start again. ”
Precautions worked, և team restored clean seawater samples. “After the 2017 expedition, standing in front of a gas chromatograph in Woods Hole, it was clear that the samples were clean, with no signs of diesel fuel,” said co-author Love. “The Pentadecan was infallible; it already showed clear oceanographic patterns even in the first few specimens [we] ran. “
Because of their huge number in the world ocean, Love continued. “Only two types of marine cyanobacteria add 500 times more hydrocarbons a year to the ocean than the sum of all other ocean oil imports, including natural oil floods, oil spills, fuel leaks and land leaks.” Collectively, these microbes produce 300-600 million tons per year, which slightly weakens the 1.3 million tons of hydrocarbons released from all other sources.
While these numbers are impressive, they are a bit misleading. The authors note that the pentagonal cycle extends 40% or more of the Earth’s surface, with more than one trillion quadrillion quadriceps loaded with cyanobacterial cells suspended in the pasture of the world’s oceans. However, the life cycle of these cells is usually less than two days. As a result, researchers estimate that the ocean contains only about 2 million tons of pentagon at any given time.
Valentine explained that it is a fast-spinning wheel, so the actual amount available at any given time is not very large. “You produce and consume the whole pentagon in one ocean every two days,” he said.
In the future, researchers hope to link the genomes of microbes to their physiology and ecology. The team already has genome sequences for dozens of organisms that have multiplied to consume the pentagon in their samples. “The amount of information out there is incredible,” said Valentin. “I think it turns out we don’t know much about the ecology of carbohydrate-consuming organisms.”
Confirming the existence and magnitude of this biohydrocarbon cycle, the team sought to address the question of whether its presence could bring the spilled oil out of the ocean. The key question, according to Arrington, is whether these microorganisms that use the huge amount of pentadecane act as active oil in cleaning up the oil spill. To study this, they added pentane, a pentadecane-like hydrocarbon, to sea water sampled at different distances from natural oil spills in the Gulf of Mexico.
They measured the total respiration in each sample to see how long it took for the pentacles to multiply the germs. The researchers hypothesized that if the quintuple cycle really favors bacteria over other carbohydrates, then all specimens should flower at the same rate.
But that was not the case. Specimens in the vicinity of the oil bloom rapidly. “Within a week of adding the penta, we saw a large population growing,” Valentin said. “And it gets slower and slower as you leave, until when you go out in the North Atlantic you can wait months, never bloom.” In fact, Arrington had to stay behind after an expedition to Woods Hall, Massachusetts, to continue experimenting with specimens from the Atlantic, as the heyday was too long.
Interestingly, the team also found evidence that another area of life, the Archaea, could play a role in the pentagonal cycle. “We learned that a group of mysterious, globally abundant bacteria that still need to be domesticated in the laboratory can feed in the basal ocean,” said co-author Arrington.
The results ask why the existence of a huge pentagonal cycle did not affect the decomposition of petrochemical pentane. “Oil is different from the pentagon,” said Valentin. “You have to understand the differences, what the components really are, in order to understand how ocean bacteria will react to it.”
After all, the genes commonly used by bacteria to consume pentane are different from the genes used for pentagon. “Bermudians living in the clear waters of the Bermuda Islands are much less likely to be exposed to the petrodecane produced by the petrochemical pentane produced by cyanobacteria, so they are less likely to carry the pentane consumption genes,” Arrington said.
Cargoes of different microbiological types can consume pentagons, but that does not mean that they can consume other hydrocarbons, Valentin continued, especially given the variety of hydrocarbon structures present in oil. There are less than a dozen common hydrocarbons in marine organisms, including pentagonal methane. Oil, on the other hand, is made up of tens of thousands of different hydrocarbons. Moreover, we now see that organisms tend to live in greater quantities near natural oil spills to break down complex petroleum products.
Valentine calls this phenomenon a “biogeographical preference” when the microbial population of the ocean is conditioned by a certain source of energy in a certain geographical area. “And what we see in this work is the difference between oil and pentagon,” he said. “It could be used to understand how different parts of the ocean will respond to oil spills.”
Nutrients such as the Sargasso Sea make up an impressive 40% of the Earth’s surface. But ignoring the earth, it still leaves 30% of the planet in search of other biohydrocarbon cycles. Valentine thinks that in high-productivity regions the processes will be more complicated և, perhaps, more preparation for oil consumption. He also noted that the Biological Hydrocarbon Production Nature Project promises efforts to develop the next generation of green energy.
Reference. Authors: “Production and consumption of hydrocarbon bacteria in the world ocean” by Conor R. Lev, Eleanor S. Arrington, Kelsey M. Goselin, Christopher M. Reddy, Benjamin As Van Mu, Robert C. Nelson և David L. Valentine, February 1, 2021 Bacteriology of nature,
DOI: 10.1038 / s41564-020-00859-8: