Isolation, Identification and Biochemical Characterization of Azospirillum spp. and Other Nitrogen-Fixing Bacteria

Abstract

Azospirillum is one of the most well-characterized genera and currently includes 15 N-fixing and one non-N-fixing species. A. brasilense is a bacterium used in agriculture in many countries since its discovery in 1978. It is found in association with many plants worldwide and can be isolated from soil as well. The main strategy used to isolate and count bacterium from this genus uses N-free semi-solid medium, and the recipe used by many authors over the past 34 years is the semi-solid NFb medium described in 1976. In this chapter, we present the procedures used for diazotrophic counting and identification either from rhizosphere soil or on the surface or within plant tissues. We also describe methods of measuring nitrogenase activity in vials containing semi-solid medium, as well as the use of carbon sources for species characterization and storage procedures.