Metabolic Labeling of Microorganisms with Stable Heavy Nitrogen Isotopes (¹⁵N)

Quantitative Proteomics based on stable isotope labeling by ¹⁵N is a versatile method in determination of changes in microbial protein expression profiles. Once set up, the workflow relies on defined chemical or commercially available complex media leading to universal heavy labeling by the stable isotope ¹⁵N. This chapter provides a detailed protocol for labeling of different bacteria and the strategy for evaluating the incorporation rate of the heavy stable isotopes in the sample is discussed.