Significant differences in the natural AM colonization level
among the test plants were evident. In T. vulgaris plants showed the
highest AM colonization levels, which were not affected by
bacterial inoculation. In contrast, all bacteria increased the
mycorrhization degree in S. chamaecyparissus and S. officinalis,
thereby acting as mycorrhiza helper bacteria (Frey-Klett et al.,
2007). Fermented agrowastes applications decreased the ratio of
AM intra and extra-radical colonization in all plants, which suggest
a particular stimulating effect of this amendment on the fungal
mycelia developed in soil, in comparison with that developed
inside the root. The extraradical mycelium size was quite similar
irrespective of plant and the bacterial inoculum involved. Thus,
significant increases of macro and micro nutrients uptake by
T. vulgaris, S. chamaecyparissus and L. dentata inoculated with
B. thuringiensis cannot be explained by an enlargement of the
extraradical mycelium emerging from the root systems of those
naturally AM-colonized plants.