Comparative analysis of bacterioplankton assemblages from maritime Antarctic freshwater lakes with contrasting trophic status

摘要

The baclerioplankton assemblages of eight maritime Antarctic lakes with a wide range of trophic status and geographic span (six lakes from Hope Bay, Antarctic Peninsula and two from Potter Peninsula, King George Island) were described using denaturing gradient gel elec-trophoresis and band sequencing during two consecutive austral summers (2003-2004). Analyses of the gels identified a total of 230 bands spread across 57 different positions. Among those bands, 14 were shared between lakes from Hope Bay and Potter Peninsula, 17 were observed only in particular lakes, and 17 were registered both years in the same lake. We successfully reamplified andrnsequenced 43 bands located in 36 different positions belonging to Bacteroidetes, Actinobacteria, Betaproteobac-teria and Cyanobacteria. The closest matches for 63% of the sequenced bands were from Antarctic or from other cold environment clones and sequences already in the databases, suggesting the widespread dominance of microbial communities adapted to cold habitats. The results of the multivariate analyses (Cluster Analysis and CCA) indicated that the nutrient status of the lake influences the bacterioplankton assemblages.