Resumo

PINEDA-MENDOZA, Rosa; MARTINEZ-JERONIMO, Fernando; GARDUNO-SOLORZANO, Gloria  e  OLVERA-RAMIREZ, Roxana. Morphogical and molecular characterization of filamentous cyanobacteria isolated from blooms in three eutrophic urban lakes in Mexico city. Polibotánica [online]. 2011, n.31, pp.31-50. ISSN 1405-2768.

Cyanobacteria are traditionally classified based on morphological and ecological traits, which can result in incorrect identifications due to phenotypic plasticity, and in the case of isolated strains, due to morphological changes provoked by the culture conditions. The gene 16S rRNA is useful for taxonomic identification, helping to overcome the aforementioned problems. Using morphological and molecular characteristics, we isolated and identified filamentous cyanobacteria present in blooms in three eutrophic urban lakes in Mexico City with the aim of recognizing genera of cyanobacteria other than Microcystis that may be present. Water samples were collected during March 2007, and through micromanipulation we obtained monospecific cultures that were preliminarily identified using morphological traits. In addition, total DNA was extracted, and a partial region of the 16S rRNA gene was amplified to corroborate the taxonomic identifications; these were confirmed through their phylogenetic positioning. In this way most of the isolated strains identified by their morphological traits could be confirmed at the generic level. We identified strains of Anabaenopsis, Arthrospira, Leptolyngbya, Limnothrix, Geitlerinema, Phormidium, Planktolyngbya, Planktothrix, Pseudanabaena and Spirulina, showing the diversity of cyanobacteria that could be recorded in blooms even though the dominant taxa could be Microcystis spp. To accurately determine taxonomic identity we strongly recommend the use of both techniques in order to avoid errors due to phenotypic variation provoked by environmental factors or culture conditions.

Palavras-chave : cyanobacteria; bloom; 16S rRNA; eutrophication; urban lake.

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