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

14 pages, 5 tablesThe bacterioplankton 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 electrophoresis and band sequencing during two consecutive austral summers (2003–2004). Analyses of the gels identi- Wed a total of 230 bands spread across 57 diVerent 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 reampliWed and sequenced 43 bands located in 36 diVerent positions belonging to Bacteroidetes, Actinobacteria, Betaproteobacteria 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 inXuences the bacterioplankton assemblagesThe Antarctic expeditions were supported by the “Instituto Antártico Argentino (DNA)”, in the framework of a cooperative project between this institution, UBA and ICM-CSIC. This work was Wnanced by grants of the Argentinean Funds for Technical and ScientiWc Investigation (FONCYT, PICT 04440 and PICT 32732), and by the Spanish projects MIXANTAR (REN2002-11396 E/ANT) and MICRODIFF (DGICYT REN2001-2120/MAR) grant SB2001-0166 from the Spanish MECyD. We wish to thank the members of the Esperanza Station for the logistic support, P. Rodriguez and E. Moreno-Díaz for their assistance with the Weld work, and Dr. Ramon Massana for general support. We also thank the reviewers for their valuable suggestions on the manuscriptPeer reviewe