Application of two-dimensional protein analysis for strain fingerprinting and mutant analysis of Azospirillum species

Abstract

Phenol-extracted total proteins from wild-type and mutant strains of Azospirillum brasilense and A. lipoferum were subjected to two-dimensional polyacrylamide gel electrophoresis. The protein patterns of both species could be readily distinguished by specific configurations of a limited number of spots. The resolving power of the technique allowed its application for strain fingerprinting. Thus, near-identity of A. brasilense strains Sp7 and Cd was demonstrated. In addition, minor changes in protein profiles resulting from spontaneous, chemically induced, or transposon-mediated mutations in the A. brasilense genome were evidenced. For a nitrate reductase negative mutant of strain Sp245 and a Sp7 mutant affected in exopolysaccharide synthesis, production of a truncated protein was involved. In Tn5-generated mutants, a gene dosage effect for the transposon-encoded neomycine phosphotransferase was observed.Key words: Azospirillum, two-dimensional protein analysis, fingerprinting.