Identification of Azospirillum species by RFLP and pulsed-field gel electrophoresis.

Pulsed-field gel electrophoresis (PFGE) was applied to analyse the restriction fragment length polymorphism of Azospirillum brasilense and Azospirillum lipoferum strains. Genomic DNA was digested by rarely cutting restriction enzymes and subjected to PFGE using the Rotaphor system. The restrictions with SpeI produced 10-20 fragments with sizes from about 10 kb to 900 kb. The separation resulted in a strain-specific banding pattern in almost every case. After Southern blotting and hybridization with 23S rRNA gene probes, the species could be determined. With the combination of both methods, identification of re-isolates from soil at the species and strain level is possible.