Natures wonders: shipworm digestion explained (Introduction)

by David Turell , Wednesday, June 05, 2024, 18:55 (103 days ago) @ David Turell

Symbiotic bacteria digest the wood lignin:

https://phys.org/news/2024-06-year-mystery-destructive-shipworm.html

"They bedeviled ancient Greek navies, helped shipwreck Christopher Columbus, aided in the sinking of the Spanish Armada and caused the wharves in San Francisco Bay to collapse into the sea, but until now, scientists have been unable to pinpoint exactly how shipworms—a family of mollusks—are able to cause such damage.

"A team of researchers, jointly led by the University of Massachusetts Amherst and the University of Plymouth, along with collaborators from the University of Maine and UMass Chan Medical School, have discovered that a population of symbiotic microbes, living in an overlooked sub-organ of the gut called the "typhlosole," have the ability to secrete the enzymes needed to digest lignin—the toughest part of wood.

"'Shipworms are such important animals," says Reuben Shipway, co-corresponding author of the research published recently in International Biodeterioration and Biodegradation and who initiated this work as part of his postdoctoral fellowship at UMass Amherst.

"'They are found throughout the world's oceans and not only have they changed history, they are also ecosystem engineers and play a fundamental role in cycling carbon in aquatic environments. It's incredible that we haven't had a full understanding of how they do this."

"Wood is a miraculous substance: flexible and tough, its stringy but nutritious cellulose can make a great meal—but only for those living things that can digest it and also get through the layer of lignin, a tough, armor-like substance that surrounds the cellulose like "wrap rage"-inducing packaging around your favorite treat. Microbiologists have long known that those animals capable of digesting lignin—like termites—host specialized, symbiotic colonies of microbes in their guts that do the work of breaking the lignin down for them.

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"It turns out that shipworms have a curious sub-organ, called a typhlosole—"it looks like Salvador Dali's mustache upside down," says Shipway—that is embedded in the mollusk's digestive tract.

"Previous researchers had thought that it served as a mixing structure, but, when Goodell and Shipway did some precise culturing work, then enlisted the aid of the Argonne National Lab's facilities for metagenomic analysis as well as the advanced genetic-probe-microscopy technique at the UMass Amherst Institute for Applied Life Sciences, they found what generations of researchers had overlooked: hidden clusters of bacterial symbionts with the capability to produce lignin-digesting enzymes."

Comment: shipworms are a mollusk and play an important role in their ecosystem, digesting any wood in water. How did Shipworms find a specific bacterium? Not by chance.