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Electric microbes: new methods of cultivating subsurface life

A black and white image of small worm like shapes which are actually bacteria.
A view of corrosive bacteria on an iron surface taken with a scanning electron microscope.

More than half of all microbes on Earth are found below the surface of the ground. These environments have limited soluble energy sources because they are isolated from surface photosynthesis. The energy sources used by subsurface life have remained a mystery as over 99% of subsurface microbes can’t be cultivated using “conventional” electron donors such as organics and hydrogen.

Discovering how subsurface microbes acquire energy will lead to the development of novel cultivation methods and enable us to utilize the vast subsurface microbial resources.

Recent studies have provided evidence that a sedimentary sulfate-reducing bacterium can access energy from solids by direct electron extraction at their cell surface. Furthermore, the proteins mediating electron uptake process are widely found in diverse subsurface microbes. The possibility exists that subsurface microbes may also access energy in the same way.

This project will verify whether subsurface microbes can be cultivated in the lab by providing electrons directly as the energy source.

If successful, this new method of cultivation will open up new possibilities to study the poorly understood subsurface microbiology and utilize the as yet untapped subsurface microbial resource for biosynthesis of new compounds such as antioxidants, antibiotics and anticancer drugs.

Project lead: Dr Xiao Deng (Environomics FSP Postdoctoral Fellow)