Culturability and in situ community composition of bacterioplankton from a high altitude wetland of northwestern Argentina

FARÍAS ME; FERRERO M; GROHMMAN E; SWEZYK U; SIÑERIZ F

Cancun, Mexico

Congreso; 10th Internacional Simposium Microbial Ecology; 2004

International Society for Microbial Ecology

Molecular diversity of bacterial community present in the water of Laguna de los Pozuelos wetland was studied by use of a molecular approach based upon rDNA. Total genomic DNA recovered from bacteria isolated from this complex community was subjected to comparative phylogenetic analysis of the gene coding for the small-subunit rRNA (rDNA). By comparative sequence analysis, the majority of the examined isolates (42 of 92) could be affiliated to the gamma subclass of the Proteobacteria. The alpha and beta subclasses of Proteobacteria were represented by six and sixteen isolates, respectively. Sixteen isolates grouped with Gram-positive bacteria with high DNA G+C content and six isolates could be affiliated to the Cytophaga-Flavobacter group. A few sequences could not be affiliated to any known bacteria. FISH resulted in the detection of a large fraction of microbes. Up to 75% of total DAPI cell counts hybridized to the bacterial probe EUB338, the highest number belong to the group of â and ã-Proteobacteria accounting for up to 30 and 20% of total DAPI cell counts, respectively. The Cytophaga-Flavobacterium cluster represented 8.5% of the total DAPI cell counts. Furthermore, members of the high G+C Gram-positive bacteria accounted for up to 8.5% of total cell counts and members of the a- Proteobacteria constituted a significant fraction in this water, 5.0 % of total cell counts.