Indicatori microbici nei suoli calcarei, strumenti per il biomonitoraggio

The aim of the research was to study through traditional methods of microbiology, the microbial component and some physiological groups and with the method of the Community Level Physiological Profile, heterotrophic activity and functional biodiversity of microbial communities in relation to vegetation cover and physical-chemical characteristics of calcareous soils along the flanks of Mounts Bardia and Tului (Dorgali). The sites who were sampled are 15 and samples were 2 in the spring. The results of microbiological analysis of soil showed the presence of a soil bacterial community numerically higher than fungal. Among the groups of microorganisms, the free nitrogen-fixers was the most abundant because of high values of C/N. The index of Shannon has not shown a good survey instrument for the high degree of redundancy of microbial communities. The Average Well Color Development showed that inoculate ecoplates with a too concentrated microbial suspension (105UFC/ml) does not highlight the differences between communities, visible inoculating a less concentrated suspension (104UFC/ml). The PCA combined with the clusters analysis showed that forest cover and overgrazing appear to be the factors most influence the soil microbial community and there seems no relationship with soil type. It’s confirmed that centrifugation is a valid technique to standardize the inoculum.