The problem with old water testing

University of Minnesota

This magnified image shows a collection of biofilms that attach themselves to stationary objects in the river, like rocks and leaves. In open water, bacteria are loose and not clustered together like this


Traditional water testing has relied on microbes that are collected from the river and grown (cultured) on a nutrient-rich medium in a lab. But there’s one big problem with that process.

The Mississippi River contains 5,000 to 10,000 species of microorganisms.

Less than 1% of all those little microorganisms can be analyzed in a lab by culturing them. Most of the other organisms can’t be grown in a lab setting. Some depend on other microbes and can’t exist in isolation. And science just hasn’t identified a great number of the thousands of different types of microorganisms in the water.

Breaking down these organisms into their genetic codes – which metagenomics accomplishes – can be a powerful tool to get around this long-standing problem. Digging into the genes of microorganisms gives us a more full picture of life on our planet.