Lovely to take a look at, hard to sample: Measuring metabolites like sucrose and polyphenols in seawater is tough. The scientists from limit Planck Institute for Marine Microbiology in Bremen needed to develop an unique approach to handle the large quantities of salt in seawater that make measurements of metabolites so difficult. Credit: HYDRA Marine Sciences GmbH
Polyphenols keep microorganisms from eating the sugar
Bacteria love sugar: It is simple to absorb and full of energy. Why isnt the sucrose consumed by the huge community of microorganisms in the seagrass rhizosphere? “We spent a long period of time trying to figure this out,” states first author Maggie Sogin, who led the research study off the Italian island of Elba and at the Max Planck Institute for Marine Microbiology.
Lush meadows of the seagrass Posidonia oceanica in the Mediterranean. Researchers at the Max Planck Institute of Marine Microbiology anticipate that their findings are pertinent for many marine environments with plants, consisting of other seagrass mangroves, types, and saltmarshes. Credit: HYDRA Marine Sciences GmbH
Sweet Spots in the Sea: Mountains of Sugar Under Seagrass Meadows
Seagrass beds are underwater sanctuaries. Now scientists have discovered huge amounts of sugars beneath seagrass meadows. This sheds new light on how plants store carbon in the ocean.
Now scientists from the Max Planck Institute for Marine Microbiology in Bremen, Germany, have actually discovered that seagrasses release massive amounts of sugar into their soils, the so-called rhizosphere. Sugar concentrations underneath the seagrass were at least 80 times higher than previously determined in marine environments.
” To put this into viewpoint: We estimate that worldwide there are between 0.6 and 1.3 million lots of sugar, mainly in the kind of sucrose, in the seagrass rhizosphere,” discusses Manuel Liebeke, head of the Research Group Metabolic Interactions at the Max Planck Institute for Marine Microbiology. “That is approximately similar to the amount of sugar in 32 billion cans of coke!”
” That is roughly comparable to the amount of sugar in 32 billion cans of coke!”
Researchers at the Max Planck Institute of Marine Microbiology forecast that their findings are appropriate for numerous marine environments with plants, including other seagrass saltmarshes, species, and mangroves. Now scientists from the Max Planck Institute for Marine Microbiology in Bremen, Germany, have actually found that seagrasses launch enormous quantities of sugar into their soils, the so-called rhizosphere. “In our experiments, we added phenolics separated from seagrass to the microbes in the seagrass rhizosphere– and certainly, much less sucrose was consumed compared to when no phenolics were present.”
Nicole Dubilier, Director at the Max Planck Institute for Marine Microbiology discusses: “Seagrasses produce sugar throughout photosynthesis. “Looking at how much blue carbon– that is carbon captured by the worlds ocean and seaside environments– is lost when seagrass communities are decimated, our research study clearly shows: It is not only the seagrass itself, but also the big quantities of sucrose below live seagrasses that would result in a loss of stored carbon.
” What we understood is that seagrass, like many other plants, release phenolic compounds to their sediments. Red red wine, coffee, and fruits have plenty of phenolics, and lots of people take them as health supplements. What is less well known is that phenolics are antimicrobials and inhibit the metabolic process of the majority of microbes. “In our experiments, we added phenolics separated from seagrass to the microorganisms in the seagrass rhizosphere– and certainly, much less sucrose was taken in compared to when no phenolics were present.”
Some experts flourish on sugars in the seagrass rhizosphere
Why do seagrasses produce such large amounts of sugars, to then just discard them into their rhizosphere? Nicole Dubilier, Director at limit Planck Institute for Marine Microbiology describes: “Seagrasses produce sugar throughout photosynthesis. Under average light conditions, these plants utilize most of the sugars they produce for their own metabolic process and development. Under high light conditions, for example at midday or throughout the summer season, the plants produce more sugar than they can use or store. They release the excess sucrose into their rhizosphere. Consider it as an overflow valve.”
Manuel Liebeke and Nicole Dubilier in the lab. Credit: Achim Multhaupt
Intriguingly, a small set of microbial experts are able to flourish on the sucrose despite the tough conditions. Sogin speculates that these sucrose professionals are not just able to absorb sucrose and degrade phenolics, but may offer advantages for the seagrass by producing nutrients it needs to grow, such as nitrogen. “Such useful relationships between plants and rhizosphere microbes are popular in land plants, but we are only just starting to understand the intimate and complex interactions of seagrasses with microorganisms in the marine rhizosphere,” she includes.
Endangered and critical habitats
“Looking at how much blue carbon– that is carbon recorded by the worlds ocean and coastal communities– is lost when seagrass communities are annihilated, our research clearly shows: It is not only the seagrass itself, but also the big quantities of sucrose underneath live seagrasses that would result in a loss of kept carbon. Our estimations show that if the sucrose in the seagrass rhizosphere was degraded by microorganisms, at least 1,54 million tons of carbon dioxide would be launched into the environment worldwide,” states Liebeke.
Up to a 3rd of the worlds seagrass might have been currently lost. “We do not understand as much about seagrass as we do about land-based habitats,” Sogin highlights.
Reference: “Sugars control the seagrass rhizosphere” by E. Maggie Sogin, Dolma Michellod, Harald R. Gruber-Vodicka, Patric Bourceau, Benedikt Geier, Dimitri V. Meier, Michael Seidel, Soeren Ahmerkamp, Sina Schorn, Grace DAngelo, Gabriele Procaccini, Nicole Dubilier and Manuel Liebeke, 2 May 2022, Nature Ecology & & Evolution.DOI: 10.1038/ s41559-022-01740-z.