ABSTRACT
Soil is the most diverse habitat on Earth, and the active microorganisms in soil drive essential global biogeochemical cycles. This chapter discusses the pros and cons of all current techniques of stable isotope probing (SIP) in soil systems and assists the reader in making a focused decision as to which application to employ. SIP is a molecular technique that supplies substrates labeled with the heavier and stable isotopes of common elements to microorganisms. An isotope is a variation of the same chemical element in which the number of neutrons in the nucleus is different. In addition to the selection of the SIP method and the choice of the target molecule, other decisions have to be made in the strategic design of a SIP experiment. The chapter provides an overview and guide to the reader to the most appropriate type of SIP to identify active microbes in a particular soil sample.
