The aims of this study were to determine whether the microbial
activities in soil compartments are influenced by ectomycorrhizal
symbiosis and to determine the functional diversity of fluorescent
pseudomonads associated with the symbiosis of Uapaca sp. and
ectomycorrhizal fungi. Uapaca sp. seedlings were cultured in soils
collected under ectomycorrhizal tree species. After 8 months culturing,
the soil highly colonized by hyphal stands (hyphosphere soil, HS), as
well as the non colonized soil (bulk soil, BS) was sampled from each
pot. The non-mycorrhizal and mycorrhizal short roots with their adherent
soil were collected and vigorously shacked, to recover the Rhizosphere
Soil (RS) and the Mycorrhizosphere Soil (MS). The patterns of in situ
catabolic potential (ISCP) of microbial communities have been measured
and the results showed that functional activities of soil microbial
communities are mainly dependent on fungal activities. In addition, this
effect is different between the hyphosphere and mycorrhizosphere zones.
The number of fluorescent pseudomonads was significantly more numerous
in the HS, MS and RS compartments than in the bulk soil. The highest
size of fluorescent pseudomonad population was in the Hyphosphere Soil
(HS) compartment. The ectomycorrhizal symbiosis has also modified the
functional activities of fluorescent pseudomonads. This fungal
qualitative effect was mainly detected in the hyphosphere soil
compartment on the ability of fluorescent pseudomonads to solubilize
tricalcium orthophosphate and to produce lipases. Close interactions
occur between the ectomycorrhizal symbiosis and the soil bacterial
communities that could increase the efficiency of the fungal symbiosis
for the host plant development.