Differences between the inoculation with single AM fungus versus the complex fungal mixture of this community were expected. Under the severe drought conditions here used, single A. trappei resulted to be the most efficient fungus in increasing L. dentata growth and in promoting C, N, P, K, Mg and Ca uptake. These results contrasts with the initial hypothesis that the inoculation with a mixture of AM fungal isolated would be better under stress conditions than a single isolate as was previously sug- gested by Caravaca et al. (2005). Variations among fungal isolates in their ability to produce biochemical changes related with plant drought stress tolerance (antioxidants enzymes, and MDA) were also observed. But the main effects attributed to the microbial ability to alleviate plant drought stress were maximized when the fungal mixture was associated with B. thuringiensis .