Ammonia-Oxidising Bacteria and Archaea in deep water of an oligotrophic subalpine lake

Despite human activities are altering the tendency of the processes of the nitrogen cycle to balance each other in freshwaters, important knowledge is still missing, in particular regarding the role of microorganisms involved in this cycle. In this study, abundance of ammonia-oxidising Bacteria and Archaea have been investigated along the pelagic water column of a deep subalpine lake (Lake Maggiore, Northern Italy). Based on sequence analysis of 16S rRNA genes and the functional genes amo, codifying for the ammonia-monooxygenase enzymes, the relative presence and importance of both ammonia-oxidising Bacteria and Archaea in deep waters have been assessed, confirming the emerging hypothesis of their spatial niche differentiation. We found a different vertical distribution of Bacteria and Archaea and here we will discuss the interaction with chemical and other limnological parameters.