Within an Antarctic sea squirt, scientists discover a bacterial species with promising anti-melanoma properties: New study brings important advances for Antarctic science and natural products chemistr

The tissues of an ascidian, or "sea squirt," are located on the icy sea floor in the South Pole and are where scientists are looking to find a new treatment for melanoma, one of the most dangerous types of skin cancer.

A research team from DRI, Los Alamos National Laboratory, and the University of South Florida were able to trace a naturally-produced melanoma-fighting compound called "palmeroli" in a new paper published today.

"We have long suspected that palmerolide A was produced by one of the many types ofbacteria that live within this ascidian host species, S. adareanum," said lead author Alison Murray, PhD, research professor of biology at DRI. We have been able to identify the specific microbe that produces this compound, which is a huge step forward towards developing a naturally-derived treatment for melanoma.

The team identified a new and previously un-studied bacterium called Candidatus Synoicihabitans palmerolidicus. Murray and her colleagues have been studying palmerolide A and its association with the host ascidian for more than a decade.

Murray collaborated with Bill Baker, the professor of chemistry at the University of South Florida, and Christian Riesenfeld, the researcher at DRI, to publish a study on the diversity of a single S. adareanum organisms. In 2020, the team expanded to include additional researchers from the University of South Florida and the University of Nantes.

The team looked more closely at the core members of the Microbiome to determine which of the 21 types ofbacteria were responsible for the production of palmerolide A.

This is the first time that we've matched a natural product from the Antarctic to the genetic machinery that makes it. "As an anti-cancer therapeutic, we can't just harvest these sea squirts and then use them as drugs, but now that we understand the underlying genetic machinery, we can find a biotechnological solution to produce this compound."

Knowing the producer of palmerolide A will allow cultivation, which will provide sufficient quantity of the compound for needed studies of its pharmacological properties.

There are many questions about the distribution of S. adareanum and its palmerolide-produced symbiont across the landscape in the ocean. A new report is about how the genes code for the palmerolide A enzymes.

In order to survive in the harsh and unusual environment of theAntarctic sea floor, ascidians and other invertebrates have developed symbiotic relationships with diverse microbes that play a role in the production of features such as photoprotective pigments, bioluminescence, and chemical defense agents. The compounds produced by these microbes can be used in a variety of ways. There are many examples yet to be discovered.

Patrick Chain, a senior scientist and Laboratory Fellow, said that the novel microbe's genome appears to harbor multiple copies of the genes responsible for palmerolide production. The role of each copy and regulation is unknown. This suggests that palmerolide is important to the bacterium or the host, though we have yet to understand it's biological or ecological role within thisAntarctic setting.

Murray said that nature is the best chemist out there. The evolutionary intricacies found between hosts and their microbial partners and the chemical handshakes that are going on under our feet on all corners of the planet are exemplary of the fact that microbes can make these bioactive and sometimes toxic compounds that can help the hosts to facilitate their survival.

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The Desert Research Institute provides materials. The original was written byKelsey Fitzgerald. Content can be edited for style and length.