Sugar turns brown algae into good carbon stores

Only highly specialized bacteria can carry out the degradation of brown algae with the help of more than hundred enzymes

Max Planck Institute for Marine Microbiology

IMAGE: The brown algae Fucus vesiculosus grows on stones almost everywhere along the North Sea and Baltic Sea. For the study the researchers also examined fucoidan of these algae like those… view more  Credit: Max Planck Institute for Marine Microbiology/M. Schultz-Johansen

You may like them or not, but almost everyone knows them: brown algae such as Fucus vesiculosus, commonly known as bladderwrack, grow along the entire German coast. Giant kelp like Macrocystis or Sargassum grow closely together along the coasts but can also form floating aggregates that can cover the Atlantic from west to east. Some ecologists see this this very productive ecosystem as a marine counterpart to rainforests on land. In these algal forests, large amounts of carbon dioxide are stored, making them an important part of the global carbon cycle.

Andreas Sichert from the Max Planck Institute for Marine Microbiology dedicated his PhD to the question how brown algae can be such a good sink of carbon: “Main constituents of algal biomass are their cell walls – a tight network of proteins and long-chained sugars. When the algae die, we actually have little clue about the fate of algal biomass in the ocean, for example which compounds are degraded fast or slowly”.

Firm and flexible

The Atlantic coast is not a cozy habitat. Tides, wind and waves demand special adaptations from the inhabitants of this harsh environment. Brown algae developed a special cell wall structure, making them both firm and flexible, and enabling the plant to successfully withstand heavy currents and waves. A major component of the cell walls is the polysaccharide fucoidan, a long-chained sugar accounting for about a quarter of algal dry mass. Likely, fucoidan can regulate the water content of the cell wall which protects brown algae from drying out at low tide.

What role this sugar plays in the long degradation process of brown algae was analyzed by scientists from the research group Marine Glycobiology at the Max Planck Institute for Marine Microbiology and the MARUM, Center for Marine Environmental Sciences at the University of Bremen. For their study, they cooperated with colleagues from the Massachusetts Institute of Technology, from the University of Greifswald and from the University of Vienna. “It was already known that microbial communities hydrolyze fucoidan slower than other algal polysaccharides and thus fucoidan might act as carbon sink” says Andreas Sichert from the Max Planck Institute for Marine Microbiology, first author of the study, published in the scientific journal Nature Microbiology in May 2020. “Usually, polysaccharides are a favorite energy source for bacteria, but the reason why fucoidan should be barely digestible remained unclear”.

Only specialists degrade this sugar

So far, the fucoidan degradation pathways were only partially known, but it was evident that they involve a substantial number of enzymes either distributed within a microbial community or housed within individual, highly specialized bacteria. The scientists from Bremen examined the latter theory and analyzed newly isolated bacteria of the genus Lentimonas, belonging to the phylum Verrucomicrobia. Even the isolation of these Lentimonas bacteria was challenging. “From initially more than thousand colonies, only one was able to degrade fucoidan in the end,” remembers Christopher H. Corzett from the Massachusetts Institute of Technology, first author of the study next to Andreas Sichert.

“We could show that Lentimonas acquired a remarkably complex machinery for the degradation of fucoidan that uses about one hundred enzymes to liberate the sugar fucose – a part of fucoidan”, says Jan-Hendrik Hehemann, leader of the research group Marine Glycobiology. „This is probably one of the most complicated biochemical degradation pathways for natural material that we know of.” Fucose is then metabolized via a bacterial microcompartment, a proteinaceous shell that shields the cell from the toxic intermediate lactaldehyde. „The need for such a complex catabolic pathway underpins the recalcitrance of fucoidans for most marine bacteria and it shows that only highly specialized organisms in the ocean are able to break down this algal sugar,” says Hehemann. „This can explain the slower turnover of the algal biomass in the environment and suggests that fucoidans sequester carbon in the ocean.”

Potential for pharmacology

Scientists are also interested in enzymes for fucoidan degradation because it may be a pharmacologically active molecule that shows similar effects to heparin in blood clotting. “Enzymes that specifically fragment fucoidan and thus help to characterize its structure are of great scientific interest because they enable researchers to understand the effects of fucoidan and to open up these marine sugars for biotechnological applications,” says Thomas Schweder, participating microbiologist from the University of Greifswald.


From EurekAlert!

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Bloke down the pub
May 29, 2020 2:19 am

No wonder CO₀ levels had been dropping so low before man came along. Lucky we did, or sea weed could’ve kept on locking away the gas of life till everything died.

Charles Higley
Reply to  Bloke down the pub
May 29, 2020 7:22 am

Really? How much seaweed do they think there is room for in the real world? Wow. Storms rip large amounts from the seashore and out to sea. Are we now going to have to protect all those shore lines from storm and wave action, just to preserve the Focus?

This goes along with the alarmists claiming that there was so much Native American farmland in N. America that they created the Medieval Warm Period. And, then the Europeans arrived with diseases and so much land returned to trees that they created the Little Ice Age. Thus, in their minds, N. America controls the planet.

Their concept of what controls climate is seriously overblown and wrong in the basics. They might as well claim that we cause summer by planting crops and cause winter by harvesting crops.

Reply to  Bloke down the pub
May 29, 2020 11:19 am

I’m guessing the aquatic macrofauna has been eating brown algae for some time now.

May 29, 2020 2:35 am

Eat the seaweed, before it sucks all the life giving CO2 out of the atmosphere!

May 29, 2020 2:52 am

research in NZ on fucoidans for cancer treatments is or was coming along ok.
flimflam wanted to sell c credits and farm kelp off tasmania coast
recently the kelp had a die off
of course it was waarm water what dun it…they say
if a few days/weeks of a warm bit of water killed it then how the hell has it survive millenia one wonders?
Id be looking for a bug

Ron Long
May 29, 2020 3:14 am

Another ill-advised rush toward carbon (they mean CO2) sequestration. Please leave the CO2 alone as it is plant food, and yes, kelp forests can have their share. I bet this study at Max Planck Institute for Marine Microbiology was funded by Global Warming money, otherwise it is just another small marine microbiologyy study.

May 29, 2020 3:58 am

This is probably one of the most complicated biochemical degradation pathways for natural material that we know of.

This reminds me of the explanation of why we have coal.

In the carboniferous era organisms that could break down wood hadn’t evolved. That meant that dead trees just piled up and turned into coal. link

We are told that, if there’s an ecological niche, something will fill it. We aren’t usually told that the evolution of that thing can take hundreds of millions of years.

Curious George
Reply to  commieBob
May 29, 2020 7:30 am

Is there any algae-based coal?

Reply to  Curious George
May 29, 2020 8:37 am

I think algae based deposits turn into oil. No coal deposits that I know of.
Where is David Middleton when you need him?

Intelligent Dasein
Reply to  commieBob
May 29, 2020 6:10 pm

A better question would be, “Why is there still coal?”

As in, why did no microorganism acquire the ability to break down the highly reduced carbon in the coal seams. Coal should have rotted away a long time ago.

Geoff Sherrington
May 29, 2020 4:20 am

And yet, people still spend fruitless energy dragging seaweed onto farm lands, pretending that it fertilises when it has NPK values as useless as a rubber boot. Others have made fortunes kidding growers that seaweed extracts have magic hormones that make your garden grow if you sprinkle it on like fairy dust.
It is so disheartening that this tedious, unscientific chore of using seaweed in horticulture has scacely advanced since the era of Tyndall and Arrhenius.
The research reported here might have promise of better future science. Geoff S

Reply to  Geoff Sherrington
May 29, 2020 6:03 am

pretending that it fertilises when it has NPK values as useless as a rubber boot.

Well said.
I wonder what the stuff looks like when you throw it into an active mulch pile and let stew for a year or so. If it does not break down, that should be obvious.
{Here in “Old Tyme” Yankee Land, a *good* mulch pile, by definition, has added cow manure. Leaves, and general yard debris are necessary but not sufficient. Must have cow manure. }
After all, cellulose and lignins are just polymeric sugars, as is starch. So the stuff in seaweed is not all that different than all the rest.
{Hat Tip to commieBob}
Yup, it took a long time to develop cellulose munching bacteria. *AND* they are all terrestrial forms. The oceanography people would never encounter them. Sooooo……..

I got an idea. Anybody got a good mulch pile?

Tom in Florida
Reply to  TonyL
May 29, 2020 6:46 am

Go to any politician’s office. They have been full of manure for decades.

Reply to  TonyL
May 29, 2020 1:24 pm

The west coast stuff (probably similar) washes on to the sand, sits there without any change for a few days, and then without any warning ‘instantaneously’ changes into what looks like an old mound of sewage & tp; then after a very short time it magically & completely disappears as well.

About 15 years ago there was an active campaign to ban on site sewer systems near bounds of one of the central Oregon coast towns … they had a picture in the paper of a poop/tp pile to help show how the “failing” septic tanks were fouling the beach. (they never did say how the (mislabeled) solids magically made it through the drainfield and onto the beach …).

When it breaks down it seems to do it in stages, and in a hurry.

Reply to  Geoff Sherrington
May 29, 2020 8:32 am

“people still spend fruitless energy dragging seaweed onto farm lands”

Apparently seaweed (maybe not the same variety?) has been successfully used for farming: “methods included mixing layers of sand and seaweed on top of rocks to create fertile soil, a technique used to grow potatoes and other vegetables.[14] The same seaweed method also provided grazing grass within stone-wall enclosures for cattle and sheep”
–Wikipedia article on Aran Islands in western Ireland

Geoff Sherrington
Reply to  Ralph Westfall
May 29, 2020 3:51 pm

It has been used for farming, but why do you add “successfully”?
This kelp for farming meme is notable for the near absence of reports of proper scientific trials. After all, people still read the old Grimm’s fairy tales.
Maybe the ani-science organic farming mob have given seaweed a tick of approval.
But this blog post reports advances in science so I should not be raising retards. Geoff S

Reply to  Geoff Sherrington
May 29, 2020 7:16 pm

When I started gardening on the biggest of the Gulf Islands in BC, I saw heather and rodos (‘acid lovers’) doing great, I bought lime soil modifiers for things that did not do well. It did not work. I had soil tested and found pH of 7.4 and 12x more Ca+2 than any other macronutrient – it was consistent with the large limestone quarry 1km away. From both agricultural info and the firm that did the analysis, I learned that with the high Ca some plants cannot absorb micronutrients. Foliar feeding of commercial seaweed extract for anything I really wanted was the only solution – spray leaves during growing season. The effects were dramatic. My roses had been OK, but suffered from blackspot from midsummer on. With the micronutrient spray, they were stupendous and resistant to blackspot. Another success was hydrangias – before the spray they died off fairly reliably. Interestingly tomatoes and corn do not need to be sprayed.

My take on seaweed ferilizer is that it provides micronutrients if the soil is deficient and not so grossly unbalanced that plants can absorb from the soil. Also, under rather unusual soil conditions, the acid/basic nature of plants can be very different

Robert of Texas
May 29, 2020 4:43 am

The seaweed can keep it’s blasted sugars…I ain’t eating it. Nor my broccoli. Sorry Mom.

Ron Long
Reply to  Robert of Texas
May 29, 2020 6:05 am

Robert of Texas, when I was vacationing on the central coast of Chile I saw persons at first light collecting the kelp that had been washed ashore during high tide. I asked them what they collected it for and they said they wash it, put it in refrigerated ships, and ship it to Japan, where it is a delicacy. They claimed to ship several thousand tons of this every year. NO, I’m not going to try any, thank you, not even with special fruit juice.

Bloke down the pub
Reply to  Ron Long
May 29, 2020 6:12 am

Crispy seaweed is delicious, though in most Chinese restaurants in the U.K. what you’re actually eating is fried spinach

John Tillman
Reply to  Ron Long
May 29, 2020 12:40 pm

Almost the only positive feature of “sushi” as practiced in Chile is the seaweed in which handrolls are wrapped.

John Tillman
Reply to  Ron Long
May 29, 2020 12:45 pm

As a fellow Oregonian, I offer this for your consideration, without comment:

Reply to  John Tillman
May 29, 2020 1:14 pm

Would go well with a side of crickets…😂

Ron Long
Reply to  John Tillman
May 29, 2020 1:41 pm

Thanks, John, but no way I’m eating anything called “Bull Kelp”!

Reply to  Ron Long
May 29, 2020 2:58 pm

Maybe some Rocky Mountain (Prairie) Oysters might be a better fit derived from 100% Beef.

Just Jenn
May 29, 2020 5:29 am

wait, stop the presses….you mean when things die they get eaten? OH NOES!!

Good for this dude that got his grant to study what he wanted to study and skew it to the alarmists that wrote the check in a very small way.

Honestly I think it’s fascinating that detritus “eaters” for lack of a better descriptive word are after the left over sugar. I hope he continues his work and finds the mechanism for extracting that sugar, it will give more insight into the vast microbial world that most don’t bother looking at.

R Taylor
May 29, 2020 5:59 am

Brits like burning silly things from far away, but maybe Germany isn’t far enough.

May 29, 2020 12:34 pm

“Potential for pharmacology — Scientists are also interested in enzymes for fucoidan degradation because it may be a pharmacologically active molecule that shows similar effects to heparin in blood clotting.”

Well, that would be good if they found a new medical application for these brown algae. None can say they are CO2 deprived, probably like they were just 20,000 years ago at the peak of the advancing glacial season over tens of thousands of years. Amazing they survive that, and then seem to do even better with higher CO2 concentrations. CO2 is good…we need to change the narrative.

May 29, 2020 1:08 pm

Abalone and I think limpets on the south western coasts of South Africa ingest kelp particles fragmented by wave action . I wonder if they have the necessary microbes/enzymes to break down fucoidin ?

May 31, 2020 2:40 am

“grow along the entire German coast” … which is staggeringly short. Why not say it grows all along the British and northern French coasts. That is about a gazillion times longer than the GErman coast.

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