ABSTRACT
The title of this chapter brings to mind the diversity and essentiality to living systems of processes associated with the biogeochemical cycles involving nitrogen and carbon. A quick perusal of any basic biochemistry text suggests a nearly endless array of metabolic enzymes that catalyze the reactions necessary for energy transformation and cell replication and survival. Indeed, on a larger scale, ecosystem stability and sustainability (terms frequently linked to native and managed systems, respectively) rely nearly in toto on a foundation of a functional microbial community, including the complexities of intermediary metabolism of the diverse soil microbial population. Fortunately, in analyzing the status of current research relating to this topic, a relatively limited number of nitrogen and carbon catabolic enzymes have served as indicators of the metabolic status or activity of the soil biological community.
