Mystery species

Year of Soils column by Kelly Ramirez

Soil is one of the most species diverse environments on earth. In fact, in just a handful of soil you can find over 5,000 different kinds of bacteria, archaea, fungi, protists, nematodes, rotifers and other eukaryotes.

However, because we cannot see most of this diversity, it can be difficult to quantify and characterize all the different species. What's more, much of the microbial (single cell) diversity - such as bacteria and fungi - is very difficult to culture (i.e. grow on a petri plate) and study in the laboratory.

For these reasons, scientists often use molecular techniques to study life in soil. All organisms, from bacteria to plants, animals and humans have a unique DNA fingerprint. We use this fingerprint to tell the difference between soil organisms.

First we collect a soil sample, knowing that inside just a gram of soil there will be millions of cells from thousands of organisms. Then we extract all the DNA and search for and organize all the different DNA fingerprints present. This process is called 'DNA sequencing'. At first it looks only like a string of letters - ATCGs - but upon closer inspection, we can separate out the different organisms.

Sometimes we find sequences that match those we have already found in the soil, and sometimes we find new sequences that may represent new species. Interestingly, when we explored the soil in New York City's Central Park, we found that only 7-15% of the diversity had been previously documented. If such a well know park can contain so many new mystery species, just think about soils around the globe!

The soil is full of undiscovered diversity, and we are continually exploring new methods to find out more about these mysterious organisms. So next time you look down at the ground and see a mushroom or a small earthworm, remember: it's only the very tip of soil diversity, and much more lives beneath the surface.

Keywords: year of soil columns