Effects of inoculation with PGPR Bacillus and Pisolithus tinctorius on Pinus pinea L. growth, bacterial rhizosphere colonization, and mycorrhizal infection

The effect of co-inoculation with Pisolithus tinctorius and a PGPR belongin g to the genus Bacillus (Bacillus licheniformis CECT 5106 and Bacillus pumi lus CECT 5105) in enhancing growth of Pinus pinea plants and the changes th at occurred in rhizosphere microbial communities and the degree of mycorrhi zation were evaluated. Both bacterial strains of Bacillus promote the growt h of Pinus pinea seedlings, but this biological effect does not imply a syn ergic effect with mycorrhizal infection. However, the positive response to mycorrhiza in a longer-term experiment it could be expected. The introducti on of both inocula causes an alteration in the microbial rhizosphere compos ition, despite the low levels of inocula that were found at the end of the assay.