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Sponge bacteria produce same toxic compounds as fire retardants

A common marine sponge hosts bacteria that specialize in the production of toxic compounds nearly identical to man-made fire retardants, according to a new study.

The new findings by researchers at at the Scripps Institution of Oceanography at the University of California, could help scientists better understand the human health implications of a powerful group of chemical compounds, known as polybrominated diphenyl ethers (PBDEs).

“For many years scientists have been finding clues that suggested nature was making these compounds,” said SIO marine chemist Brad Moore, a senior author of the study. “Now that we understand how they are produced in the marine environment, we are exploring why they exist, and the human health concerns associated with them.”

Vinayak Agarwal, a researcher at SIO, re-launched the new study first started nearly 50 years ago by SIO chemist John Faulkner, an early pioneer in the study of natural products from the sea. Agarwal continued Faulkner’s investigation into the source of toxic PDBEs, found in large quantities in the world’s oceans.

“For the first time we were able to conclusively show that genes and enzymes produced in bacteria from sponges are responsible for the production of these compounds toxic to humans,” said Agarwal, co-first author of the paper along with Scripps researcher Jessica Blanton.

In 2014, Agarwal and colleagues were first to discover that unrelated free-living marine bacteria produce the fire retardant compounds naturally.

Researchers took the research a step further by using genome “mining” and environmental DNA sequencing to identify the specific genes and enzymes involved in the overproduction of the toxic molecules in sponges.

Marine sponges obtain food and oxygen by filtering seawater through the pores and channels in their bodies. This constant flow of water means that the immobile animals host many bacteria, viruses and fungi in complex microbiomes.

Researchers collected 18 sponge samples for the study  then isolated the various components in the complex mixture of organisms from the sponge’s tissues to identify the specific genes and enzymes that code for the production of PBDEs.

The genome “mining” approach along with metagenomic sequencing gave the scientists a way to connect the natural chemicals produced by organisms back to the enzymes that constructed them.

“We care about naturally produced PBDEs because they end up in the food chain,” said NIEHS’s Frederick Tyson. “Preliminary data from this research team suggest that some naturally occurring PDBEs may be even more toxic than those that are man-made, so we need to develop a better understanding of these compounds.”

The next step is to mine the genes and enzymes in other marine species to found out what other organisms are making similar toxic compounds and why.

By: David Beasley Staff Writer

Source: National Science Foundation

Image: Jason Biggs

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