Methods for the Characterization of Plant-Growth Promoting Rhizobacteria.

A detailed description of methods most frequently used for the identification and characterization of beneficial microbial strains is presented in this chapter. The methods include microbiological, biochemical, and molecular approaches. Microbiological and biochemical methods comprise a broad range of techniques that are based on the analysis of phosphate solubilization, nitrogenase activity, indole-3-acetic acid production, bacterial motility, presence of catalase and nitrate reductase enzyme, Gram's staining of the cell wall, siderophore production, and microbial chemotaxis. The molecular methods involve a range of techniques that are based on the extraction and analysis of microbial DNA. The extracted nucleic acid can be specifically amplified using polymerase chain reaction (PCR), and subsequently cloned and sequenced. The sequencing of conserved genes such as internal transcribed spacer (ITS) region or 16S rRNA in a microbial genome is used extensively in resolving taxonomic identity of microbial strains. These methods are highly sensitive and allow for a high degree of specificity.