The objective of this work was to determine the capacity of actinomicetes for organic phosphorus mineralization and their rhyzospere

interaction with mycorrhiza of Trifolium repens L. (white

clover). In January 2009, at the laboratory of the Unidad de

Investigaciones Agropecuarias (UNIDIA) of the Pontifi cia

Universidad Javeriana, Bogotá, Colombia, the phosphatase

activity of Streptomyces sp. (strain MCR9), Streptomyces

sp. (strain MCR26) and Thermobifi da sp. (strain MCR24)

were determined using the p-nitrofenil phosphate technique.

Thermobifi da sp. (strain MCR24) showed the lowest activity.

Inoculation of actinomycetes alone resulted in higher values

of inorganic soil P, while leaf P content was higher when coinoculation

of actinomycete-Glomus sp. occurred, with the

exception of the strain Thermobifi da sp. (strain MCR24). Coinoculation with actynomicetes and Glomus sp. stimulated

biomass production and colonization percent. Actynomicetes

are sinergistic with Glomus sp., resulting in benefi ts for the

plant and the mycorrhiza. Analysis of variance and “t” tests

ALS (P<0,05) were conducted to compare the treatments.

The relation between the degree of mycorrhization plant dry

weight was determined by the “r” correlation coeffi cient, and

plants associated with microorganisms was higher than 70%.

Keywords: Streptomyces sp., phosphatases, solubilization, arbuscular mycorhiza.