Wheat colonization by determinate bacteria

Abstract

The ability to colonize wheat by determinate strain in soil, in competition with the total soil microflora, was investigated with three mutants of strain pseudomonads which contains the nptII gene, which codes for an aminoglycosidephosphotransferase, this enzyme confers antibiotic resistance to both neomycin and kanamycin. Number of bacteria was obtained from bulk soil, rhizosphere and rhizoplane, using phase contrast microscopy. Mutants were detected using selective agar for pseudomonas supplied with neomycin and genomic fingerprinting of bacteria used molecular genetic method ERIC-PCR. On the rhizoplane, number of all three mutants where similar at about 104 per 3cm root, but the total heterotroph population varied so that the proportion of mutants appeared to vary from 6.3% for PCM40074 to 20% for PCM40313, to 84% for PCM40326. This could be due occasion but by observation of 24 colonies of heterotrophs isolated on TSA, 10 were positively identified as PCM40326 using ERIC-PCR and antibiotic- resistance phenotype on selective agar and indicates that it may be more competitive than the other two mutants.