New way to discern what microbes eat

The researchers use a mass spectrometer to measure with very high accuracy the mass of molecules derived from the microbes in a community. Then they use a newly developed software program that allows them to link microbes with their substrates.

The basis for connecting microbe and substrate are so-called carbon stable isotope ratios -- the ratios between naturally occurring forms of carbon with different masses. Nature contains both carbon-12, the most abundant form, and carbon-13, which has one more neutron than carbon-12. Each material has a very specific ratio of these two isotopes, which essentially can be used as the fingerprint or signature of the material. The new algorithm links the carbon isotope ratios of the substrates that are available to microbes in a given environment to the ratios found in the microbes themselves. Read more.