Flame retardant from the sea

Even marine bacteria produce toxic environmental hormones

Ocean Habitat: Bacteria also produce environmental poisons © freeimages
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Environmental toxins - not just man-made: Numerous marine bacteria produce a class of toxins that serve humans as a flame retardant, US researchers have found. So far, man alone has been responsible for the pollution of the sea with these substances. Genetic studies are now to provide more information on where the toxins come from and how they are distributed in the food chain, the researchers write in the journal "Nature Chemical Biology".

The oceans of our planet are increasingly burdened by persistent pollution with toxins of all kinds. Especially treacherous among the accumulated environmental poisons are the so-called endocrine disruptors, often also known as "environmental hormones": these are pollutants that enter the environment and endocrine disruptors. may have similar effects on living organisms. Long-term damage due to the disturbed hormone balance are possible consequences.

Previously attributed exclusively to humans

However, some of these environmental toxins do not appear to come exclusively from human production: a large group of marine bacteria also produces a class of substances that have so far been attributed to human pollution in the oceans - so-called polybrominated diphenyl ethers (PBDE). A team of scientists led by Bradley Moore of the University of California at San Diego has discovered through genetic testing that these PBDEs are excreted by bacteria in a wide variety of marine habitats, from sediments to seagrass and algae to coral reefs.

PBDE has long been known to humans: as an additive in textiles, insulation materials and electronic components, they raise the temperature at which the objects catch fire. As a fire retardant they are therefore very effective. However, they are also strong endocrine disruptors. Thus, one of the PBDEs identified by Moore and colleagues in the bacteria acts as the most active human thyroid hormone.

Surprising and a little bit disturbing

"We find it very surprising and also a little disturbing, " said Moore, "that flame-retardant-like chemicals are also biologically synthesized by marine-borne bacteria." PBDEs are degraded only very slowly in nature. In the body, they accumulate in the fatty tissue and accumulate in the food chain. For many Americans and Canadians, certain PBDEs are detectable, although they have not been present in cars or everyday items for years - just because they are so poisonous and resistant, they are rarely used today. display

In the fatty tissue of marine mammals such as whales and seals, the flame retardants are particularly strong. There, they even count as one of the possible causes for the dwindling existence. So far, however, scientists have assumed that the PBDEs detected in marine mammals are solely the result of increasing human pollution. According to the new results, the bacteria could be partly responsible.

Generous search for other sources

How high the proportion of bacterially produced environmental hormones is is still unclear. Therefore, the scientists want to find other possible sources of pollutants. To do this, they searched gene databases and found ten genes involved in the synthesis of environmental hormones. They also found out that the bacteria not only produce PDBE, but more than 15 related substances.

"The next step is to look generously for these genes in the marine habitat, " says lead author Vinayak Agarwal of the University of San Diego, "with the help of the identified producers Researchers are gaining further insights into how the substances in the food chain are distributed.

(Nature Chemical Biology, 2014; doi: 10.1038 / nchembio.1564)

(University of California, San Diego Health Sciences, 01.07.2014 - AKR)