Changes in active microbial soil communities in agricultural managments: from anthropic to natural.

The goal of this research was to study the composition of active eubacterial microflora by RNA extraction from bulk soil under different environmental impact managements. We examined a hilly basin in Gallura (Sardinia) where it is possible to observe an ecological progression from an intensive agricultural practice (vineyard with traditional tillage) to a conservative condition (cork oak forest) through intermediate steps (grassy vineyard, temporary grassland, pasture). A molecular analysis of the total eubacterial population was carried out by electrophoretic separation performed by Denaturing Gradient Gel Electrophoresis (DGGE) of amplified cDNA fragments obtained from 16S rRNA. UPGMA (Unweighted Pair Group Mathematical Average) analysis revealed the presence of separate clusters of eubacteria depending on soil management. Our results indicate that soil management influences the activity of microbial communities. Intensive agricultural practices reduce the biodiversity of active microbial species while low environmental impact managements, such as pasture and forest, increase biodiversity. In autumn, the differences among managements are less marked then in spring even though clustering is still present.