Genetic and phenotypic diversity of Bacillus polymyxa in soil and in the wheat rhizosphere

Article Abstract:

Three populations of Bacillus polymxya isolated from wheat rhizoplane (RP), the rhizosphere soil (RS) and the nonrhizosphere soil (NRS) were characterized phenotypically, serologically and genetically. The results of phenotypic characterization showed that the level of divergence of B. polymyxa strains depended on their origin. The RP bacteria could be classified into one phenotypic group, although the NRS and the RS strains were more diverse. These results were confirmed by serological and restriction fragment length polymorphism analysis. The results show that wheat roots select for specific types of B. polymyxa.

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Metabolic and genotypic fingerprinting of fluorescent Pseudomonads associated with the Douglas fir-Laccaria bicolor mycorrhizosphere

Article Abstract:

Fluorescent pseudomonads from the micorrhizosphere of Douglas fir with Liccaria bicolor were analyzed to determine the effects of the Douglas fir mycorrhizosphere on the phenotypic traits of the pseudomonads. Genotypic characterization of isolates of Pseudomonas fluorescens from Douglas fir indicated the stimulatory effects of the mycorrhizosphere on the size of the populations of fluorescent pseudomonads in the soil. The micorrhizosphere of Douglas fir also counterselected Pseudomonas fluorescens V and II strains compared to Pseudomonas fluorescens bv. I strains.

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Rapid in situ hybridization technique using 16S rRNA segments for detecting and differentiating the closely related gram-positive organisms Bacillus polymyxa and Bacillus macerans

Article Abstract:

Rapid in situ hybridization using 16S rRNA segments effectively detectedand identified Bacillus polymyxa and B. macerans. The probes were labeled with a fluorescent tracer and fluorescence analysis was performed on both individual cells and cultures. B. polymyxa-specific probes only had 60% homology with the B. macerans and produced fluorescence ratio measurements that were much higher for its specific bacterium. The converse was also true for the B. macerans-specific probes. The new technique is said to be faster and more convenient than standard procedures.

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