evolution: how bacteria protect Antarctic worms (Introduction)

by David Turell , Friday, June 21, 2024, 21:12 (153 days ago) @ David Turell

By producing anti-freeze:

https://www.sciencenews.org/article/bacteria-marine-worms-survive-cold

"Specialized bacteria living inside three different species of Antarctic polychaetes make proteins that help the worms not freeze to death, Corinaldesi and colleagues report June 21 in Science Advances.

"The finding illustrates how important microbes can be for their hosts, says Amy Apprill, a microbial ecologist at Woods Hole Oceanographic Institution in Massachusetts who wasn’t involved with the study. “Our knowledge of host-microbe interactions in the ocean is still incredibly limited.”

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"The most common bacteria found in the worms were Meiothermus silvanus and two types of Anoxybacillus, which were not found in a separate analysis of the sediment itself or within DNA collected from other related worms.

"Bacterial proteins extracted from the polychaetes are known to be involved in cold tolerance. Two enzymatic proteins, for example, produce glycerol and proline, which are thought to protect against extreme cold “due to their ability to reduce the freezing point of internal liquids,” Corinaldesi says.

"Though missing from today’s Antarctic ocean floor, Meiothermus bacteria have previously been found in frozen sediment from underneath the nearby Ross Ice Shelf, which “suggests a long-term connection between polychaetes and these bacteria,” Corinaldesi says. She and colleagues think that the bacteria are passed down from parent worms to their offspring.

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"The bacteria benefit from their partnership with the worms too, Corinaldesi says, as they receive a safe home in exchange for making protective proteins."

Comment: it is a perfect arrangement. If both species migrated from warmer areas into colder climates, it could explain the relationship. But that raises the issue of why the bacteria were producing antifreeze in a warm climate, and why they would get together with mutual benefits, if not needed. Worms crawl in seabed's so picking up the bacteria poses no problem. The most likely origin is they adapted together somehow.