Résumé
Plant growth is frequently limited by the availability of inorganic phosphorus (P) in the soil. In most soils, a considerable amount of the soil P is bound to organic molecules. Of these, phytate is the most abundant identifiable organic P form, but is not readily available to plants. In contrast, microorganisms have been shown to degrade phytate with high efficiency. The current study aims to characterize the members of the phytate-hydrolysing bacterial community in rhizosphere, and the molecular and enzymatic ability of these bacteria to degrade phytate.
The phytate-hydrolysing bacterial community was characterized from the rhizosphere of plants cultivated in the presence or absence of phytate supplementation. Major changes in the bacterial community structure were observed with both culture-dependent and -independent methods, which highlighted the predominance of Proteobacteria and Actinobacteria. Phytase activity was detected for a range of rhizobacterial isolates as well as the presence of, beta-propeller phytases (BPP) for both isolates and directly in a soil sample.
A wide taxonomic range of functional phytate utilizers have been discovered, in soil bacterial taxa that were previously not well known for their ability to utilise phytate as P or C sources. This study provides new insights into microbial carbon and phosphorus cycling in soil.