Phosphorus solubilization and pH changes as a result of the interactions between soil bacteria and arbuscular mycorrhizal fungi on a medium containing NH4+ as nitrogen source

This paper reports the effects of Glomus intraradices (Schenck & Smith) external mycelium, mycorrhizal, and nonmycorrhizal transformed carrot roots (alone or in interaction with Pseudomonas aeruginosa (Schroeter) Migula, Pseudomonas putida (Trevisan) Migula, or Serratia plymuthica (Dyar) Bergey et al.) on phosphorus solubilization and pH changes of the medium. All experiments were conducted in a two-compartment Petri plate system with a NH4+ medium containing an insoluble source of phosphorus (P). In interaction with P. aeruginosa, G. intraradices mycorrhizal roots and G. intraradices external mycelium enhanced solubilization of sparingly soluble sources of phosphates above the levels reached with each culture alone. These improvements were correlated with changes in the pH of the media.