The 13C/12C isotopic ratio of geological rocks of different ages has been used as evidence for or against past biological activity, because the biological and geological origins of these two isotopes .
Describe how FISH can be used to determine which cells within a microbial community are actively degrading toluene. Assume the genes involved in the metabolic pathway have been sequenced from several microorganisms and vary only slightly from one another.
Explain how flow cytometry can be used to study distinct microbial populations within a complex marine community. Provide specific examples of the different populations that could be studied individually.