Bacterial community diversity in ultraoligotrophic Andean lakes

BERTONI, R.; CORNO, G.; CARAVATI, E.; MODENUTTI, B.E.; BALSEIRO, E.G; CALLIERI, C.

Parma, Italia

Congreso; SITE 2008; 2008

AIOL

The North Patagonian Andine lakes are unique environments with a simplified trophic chain dominated by mixotrophic organisms. Up to now no data have been published on the bacterial community inhabiting these ultraoligotrophic lakes. From one side the presence of mixotrophic flagellates and ciliates supports the existence of an important bacterial compartment. On the other hand, the high UV radiation and the low temperature could create conditions for a slow growing bacterial community. In austral summer 2006 we measured the bacterial activity with 14C Leucine uptake method for some of those lakes. A very low activity (around 0.1 μgC l-1) indicated the existence of high limiting conditions for bacterial growth. In 2008 we extended the study to other lakes with the aim to measure the bacterial abundance and biovolume and to study the diversity of bacterial assemblages using molecular approaches. The Denaturing Gradient Gel Electrophoresis (DGGE) was used to assess the Operational Taxonomic Units (OTU) diversity and a number of selected bands from DGGE gels were sequenced for a deeper phylogenetic study. The results will be here discussed, evaluating the relationship between the geographical location of the lakes (or their physical connection) and the respective bacterial community composition.