As fruit bodies of the ectomycorrhizal fungus, Scleroderma spp., are regularly observed
around the termite mounds of Macrotermes subhyalinus (MS) (a litter-forager termite), the
hypothesis of the present study was that the epigeal mound material was inhabited by a
specific microflora that could enhance with the ectomycorrhizal fungal development. In order
to verify this hypothesis, we tested the effect of this feeding group mound material on the
ectomycorrhization symbiosis between Acacia holosericea, (an Australian Acacia introduced
in the sahelian areas) and two ectomycorrhizal fungal isolates of Scleroderma dictyosporum
(IR408 and IR412) in greenhouse conditions. The influence of the mound material
amendment on the functional diversity of soil microflora has also been assessed as well as the
diversity of fluorescent pseudomonads since it has been previously demonstrated that most of
the Mycorrhiza Helper Bacteria (MHB) belong to the fluorescent pseudomonad group. In
addition, a strain of fluorescent pseudomonad (Pseudomonas sp. KR9) was studied for its
effect on S. dictyosporum IR412 ectomycorrhizal formation.
The results showed that the termite mound amendment significantly increased the
ectomycorrhizal expansion. MS mound amendment and ectomycorrhizal inoculation have
induced strong modifications of the soil functional microbial diversity by promoting the
multiplication of carboxylic acid catabolizing microorganisms. The phylogenetic analysis
showed that fluorescent pseudomonads mostly belong to the P. monteillii species. One of
these, P. monteillii isolate KR9, increased the ectomycorrhizal development between S.
dictyosporum IR412 and A. holosericea. Hence this bacterial species could be involved in the
enhancement of the ectomycorrhizal formation recorded in the present study.
In conclusion, the occurrence of MS termite mounds could be involved in the expansion of
ectomycorrhizal symbiosis and consequently, this positive effect could be implicated in
nutrient flow and local diversity.