Natures wonders: sponges collect molybdenum (Introduction)

by David Turell , Sunday, October 20, 2024, 16:35 (32 days ago) @ David Turell

With symbiont bacteria:

https://www.sciencealert.com/rare-sea-creature-hoards-toxic-metals-as-a-fascinating-sur...

"Take a sea sponge called Theonella conica. This unassuming animal can be found in the Red Sea and Indian Ocean, doing what sponges do, filtering the seawater around them to extract the nutrients within. Anchored in place, with little in the way of active defense, T. conica has evolved a truly fascinating means of survival.

"Scientists studying the accumulation of pollutants in the sponge's body found concentrations of a heavy metal called molybdenum that, in other organisms, would be fatal.

"'Twenty to thirty years ago, researchers from our lab collected samples of a rare sponge called Theonella conica from the coral reef of Zanzibar in the Indian Ocean and found in them a high concentration of molybdenum," says marine biologist Shani Shoham of Tel Aviv University.

***

"We, and other organisms, need some molybdenum. It's an essential trace element that our bodies use to break down things like drugs, toxins, and sulfites. Like many things, though, too much molybdenum is not especially good for us, and even worse for other animals.

"So how, and why, T. conica is able to accumulate and hoard so much of the metal was something Shoham and her colleagues wanted to understand.

"The answer came in the form of the sponge's bacterial symbionts.

"As a sea sponge, T. conica is pretty simple. It has no organs, no tissues, and no nervous system. To function, it relies on symbiotic relationships with other organisms, including bacteria, funguses, algae, and viruses. As much as 40 percent of its body weight consists of symbionts.

***

"One of the most dominant bacteria in T. conica, the researchers found, acts as a sort of detoxifying organ for accumulating heavy metals in the sponge's body. It's called Entotheonella sp., a bacterium found in a few different sponges and known for its ability to produce a wide range of bioactive compounds.

"Shoham and her colleagues found globs of material inside Entotheonella sp. that had very high molybdenum content.

"Molybdenum is toxic when its concentration is higher than its solubility in water. The bacterium, the researchers believe, collects molybdenum and converts it into safe molybdenum compounds, such as calcium molybdate and sodium molybdate.

"'Hoarding more and more molybdenum, the bacteria convert it from its toxic soluble state into a mineral. We are not sure why they do this," Shoham says.

"'Perhaps the molybdenum protects the sponge, by announcing: 'I'm toxic! Don't eat me!', and in return for this service the sponge does not eat the bacteria and serves as their host."

***

"Entotheonella was found to be largely responsible for hoarding the metals and turning them into minerals, thereby neutralizing their toxicity," Shoham explains."

Comment: a sponge is like a cave for a bacteria to nestle in. It's existence there is not a surprise. But the bacteria collecting molybdenum is a surprise. That it protects sponges is a secondary effect. Design not needed, all happened naturally