Microbes clean up

It may sound counterintuitive to use a microbial protein to improve water quality. But some bacteria are doing just that to protect themselves from potentially toxic nanoparticles in their own environments. Clean up crews of the future could potentially do the same thing on a larger scale.

A team from Lawrence Livermore National Laboratory, UC Berkeley and Lawrence Berkeley National Laboratory found that bacteria from an abandoned mine excrete proteins that cause metal nanoparticles to aggregate. The bacteria are binding and immobilizing the metals in the nanoparticles and the nanoparticles themselves, which are potentially toxic to the bacteria.

Sulphate-reducing bacteria can cause heavy metals such as zinc (Zn) to precipitate and form nanoparticles. However, these particles are able to move freely because they are so small (typically 2-6 nanometres in diameter) and can redissolve if conditions change.

In the case of the mine bacteria, the researchers showed that the bacteria are causing the nanoparticle aggregation, thereby protecting themselves. When the metal nanoparticles aggregate, they don’t move as easily and are less soluble.