The use of nirK gene for the evaluation of a buffer strip assessed for enhancing denitrification

Specific soil microbial populations and activities could be promoted by suitable manipulation of the environment they live in. If correctly applied such an approach could become a very effective way to remediate excess of chemicals. The concentration of nitrogen, especially nitrate deriving from agricultural managements, is generally found to increase in water flow. Therefore, by forcing the water flow through a buffer strip specifically designed and possibly afforested with suitable plant species, may result effective in reducing high nitrogen contents. The management of a riparian buffer may definitely affect the soil microbial activities, including denitrification, as well as the composition of the community. The present study reports on the changes occurred in terms of denitrifying microbial community composition, as compared to that of a neighbouring agricultural area, as a consequence of hydraulic management coupled to the suspension of farming practices and to the development of the woody and herbaceous vegetation. With this aim, denitrification was constantly measured and the data obtained were related to those deriving from a specific analysis of the soil community composition performed both as a general bacterial population survey and as a direct determination of specific bacterial groups involved in denitrification. nirK, encoding for nitrite reductase, an enzyme essential for the conversion of nitrite to nitric oxide and considered the key step in the denitrification process, was choosen as the target gene.